Date: Tue, 13 Jan 1998 19:17:05 -0500 From: George Berven Subject: COZY: polyester question Just a small question from lurker-land. I'm in the process of building my epoxy balance and am using polyester to make some small parts for it. I would like to do the lay-ups between two plastic sheets which from what I've seen works great with epoxy. Can I use a clear plastic (polyethelene?) or a trash bag, or do I have to use aluminum foil? I'd rather see the lay-up to assure wet-out and aluminum foil rips too easily. Just thought to ask before I stink up the house and ruin a part. Thanks. George Berven gberven@erols.com Still Pre-Build but learning alot. From: Jim Hocut Subject: RE: COZY: polyester question Date: Tue, 13 Jan 1998 22:46:22 -0500 I use the 3 mil thick plastic sheet available at most hardware stores, works great. I've just recently tried aluminum foil and it does have an advantage when you need to get a layup (BID tape for instance) into a tight spot. You can have your cake and eat it too in these instances by putting the foil on the bottom, marking the exact size you need with a felt pen, and using plastic on top. After the cloth is wet out you cut to exact size with the handy "pizza cutter". Jim Hocut jhocut@mindspring.com Just a small question from lurker-land. I'm in the process of building my epoxy balance and am using polyester to make some small parts for it. I would like to do the lay-ups between two plastic sheets which from what I've seen works great with epoxy. Can I use a clear plastic (polyethelene?) or a trash bag, or do I have to use aluminum foil? I'd rather see the lay-up to assure wet-out and aluminum foil rips too easily. Just thought to ask before I stink up the house and ruin a part. From: Marc J. Zeitlin Subject: COZY: polyester question (fwd) Date: Wed, 14 Jan 98 9:43:15 EST George Berven writes: >it. I would like to do the lay-ups between two plastic sheets which >from what I've seen works great with epoxy. > Can I use a clear plastic (polyethelene?) or a trash bag, or do I have >to use aluminum foil? I use 4 mil poly sheets (dropcloths) that I get at the hardware store. Works great. -- Marc J. Zeitlin Email: marcz@an.hp.com From: lschuler@cellular.uscc.com Date: Wed, 14 Jan 98 09:26:48 -0600 Subject: RE: COZY: polyester question --simple boundary Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Description: "cc:Mail Note Part" Jim Hocut wrote: >I use the 3 mil thick plastic sheet available at most hardware stores, >works great. I've just recently tried aluminum foil and it does have >an advantage when you need to get a layup (BID tape for instance) into >a tight spot. You can have your cake and eat it too in these >instances by putting the foil on the bottom, marking the exact size >you need with a felt pen, and using plastic on top. After the cloth >is wet out you cut to exact size with the handy "pizza cutter". I use the 3 Mil as well. Saran wrap sucks. Period. Nice for getting and keeping air out of a compound curve, but that's the only reasonable use I've found for the stuff (so far). I usually mark the bottom side of the 3 Mil plastic in shape/size to be cut with a sharpie (most any color other than the color of the epoxy seems to work fine). The epoxy/glass is fairly transparent after wet out. After wet-out, just use pizza cutter to cut on the lines. Seems to work best with 4 or fewer plies. Byond that, the glass tends to get pushed around by the cutter. Havn't tried the 2-ply plastic trick (one top and one bottom); that might keep glass in line???? Foil works too, but the sharpie markings tend to bleed off the foil severly when wetting out. Maybe marking on the top plastic would work better??? Foil is nice for some corner layups because it holds it's shape better once you crease it. FWW. Larry Schuler Plans #500 lschuler@cellular.uscc.com Date: Mon, 19 Jan 1998 08:37:36 -0600 (CST) From: "Tom G. Brusehaver" Subject: COZY: Sticky epoxy I did the shear web on saturday. It took a loong time, which is why I am discouraged. I already know the answer, but I am just gonna ask anyway. I got a sticky stuff dispenser from a friend recently, and modified it following the instructions in the wicks catalog. (move the pivot point in 1.1 inches). That seemed to work, but I noticed the epoxy was taking longer to setup. It would setup, but just over a longer period of time (48+ hours). When I measure the ratio on my balance, it seems close, but maybe the hardner is a little short. While doing the layup, I ran out of hardner in the container, on one pump. I mean the container wasn't empty, but it was below the inlet hole. So I had a batch that was even shorter of hardner than I really need. This morning the epoxy was still soft. The scratch test wasn't great, I was able to chip up white stuff, but I could dent the surface by poking a nail straight into it. I know I am not still not at 48 hours, but I just think something is not acceptable. I assume the layup is junk, but I am wondering if there is a way to peel it, or something. (probably not). From: cdenk@ix.netcom.com Date: Mon, 19 Jan 1998 09:16:34 -0600 (CST) Subject: Re: COZY: Sticky epoxy Several items come to mind: 1: My epoxy pump came with 2 graduated paper cups to check the ratio. These cups should be available at a drug store to medical/laboratory supply house. The ratio should be checked occasionally. Should for first time pump a stroke or 2, mix, and ensure it sets up. the same should be with new containers of epoxy. I had some 4 year old West. the fast hardner was still OK, but the slow hardner was rubbery. I checked before using. 2: When pumping, always watch the material coming out of the tubes, color, viscosity, quantity. If the pump inlet becomes exposed (first due to material not flowing as quickly as required) the steady stream from a tube is replaced with spurts of air, which can usually be heard easily. Don't even think about costs, the slightest indication of something not perfect, check out whats gone wrong, and discard the batch. Probably the cause is the air instead of material. 3: As whats done, I suspect that the easiest thing will be to start from scratch, it might be possible to do partial removal, but I think you'll find the following: a: First not only must the offending fiberglass be removed, but all traces of the defective epoxy removed. Thats, going to be impossible to do without harming the UNI layups on the shear web. Note that sanding will tend to smear and work into the pores. This is not removing. b: Now that you try to salvage the foam, its so much softer than the fiberglass, it will be futile. c: It might be possible to cut away local (though relatively large) areas, and patch. I tend to think that the effort trying to save some areas will result in more work, and a patch job that may be unreliable. d: The spar is one of the most important structures of the airframe. This is not the time to take the quickest or cheapest route. Now that you have built one, and have the jig, the second will go much quicker. From: Marc J. Zeitlin Subject: COZY: Sticky epoxy (fwd) Date: Mon, 19 Jan 98 11:53:56 EST Tom Brusehaver wrote: >While doing the layup, I ran out of hardner in the container, on one >pump. I mean the container wasn't empty, but it was below the inlet >hole. So I had a batch that was even shorter of hardner than I really >need. >This morning the epoxy was still soft. The scratch test wasn't great, >I was able to chip up white stuff, but I could dent the surface by >poking a nail straight into it. I know I am not still not at 48 >hours, but I just think something is not acceptable. Three comments: 1) You didn't mention which epoxy you're using, but: wait for 3 or four days (if not a week) and then do your scratch test. It may be the case that the epoxy will just take a lot longer to cure. If you can jack the temperature of your workshop area up to 80 F - 90 F for that time period, you can accellerate the curing even more. If, after a long term high temp. cure you get a good, solid, clean scratch, and cannot see a hardness difference between this layup and your others, I'd say you're probably OK. 2) While I'm not quite as skeptical of your ability to save the part as Carl Denk is, I think it would be very difficult to sand off the shear web and leave clean foam below. I might give it a try, though (if #1 doesn't work) by making a LOT of dust with a belt sander until you've almost gotten rid of the shear web, and then removing the rest of the layup with 36 grit by hand. _IF_ and only if you can get a clean substrate, then re-layup the shear web. Otherwise, follow Carl's advice and make a new foam part with a new shear web. 3) I have run out of hardener also, while in the middle of a layup (a small one, and one which I could easily do over). I learned to check my pump before every layup to ensure that I'd have enough epoxy to finish with some to spare - if I can't be absolutely sure I've got enough, I either reload the pump with more or don't start. Sorry you had to learn this one the hard way on a large layup :-(. Good luck. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Mon, 19 Jan 1998 11:02:00 -0600 (CST) From: "Tom G. Brusehaver" Subject: Re: COZY: Sticky epoxy (fwd) > >1) You didn't mention which epoxy you're using, but: wait for 3 or > four days (if not a week) and then do your scratch test. It may be > the case that the epoxy will just take a lot longer to cure. If you > can jack the temperature of your workshop area up to 80 F - 90 F for > that time period, you can accellerate the curing even more. If, after > a long term high temp. cure you get a good, solid, clean scratch, and > cannot see a hardness difference between this layup and your others, > I'd say you're probably OK. I am using PT&MW AeroPoxy. > Sorry you had to learn this one the hard way on a large layup :-(. I was getting good at the balance, but the guy practically gave me the pump, so I decided to switch. It was a teething thing, I saw hardner in there, just nothing came out :-/. From: DFinn7971 Date: Mon, 19 Jan 1998 12:14:12 EST Subject: Re: COZY: Sticky epoxy In a message dated 98-01-19 09:42:12 EST, tgb@DM.netco.com writes: << I assume the layup is junk, but I am wondering if there is a way to peel it, or something. (probably not). >> I suggest you contact Nat Puffer on this to get his input. I did have a bad layup several years ago over a flat surface (similar to the shear web). I built a simple jig for my router and quickly stripped the whole layup off. If Nat feels you should start over ask him about this technique. I ended up with a thin layer of micro left on the foam and basically did my layup from scratch over it without reapplying micro. This is the same as the hard shell method discussed earlier. The area I worked in was not structural but I would think it would be OK for your shear web. Dick Finn Date: Mon, 19 Jan 1998 21:51:01 -0500 From: "Jeff S. Russell http://www.AeroCad.com" Subject: Re: COZY: Sticky epoxy (fwd) Marc J. Zeitlin wrote: > Three comments: > 1) You didn't mention which epoxy you're using, (snip) how cold is your shop temp when using the epoxy and after you finish the layup at let the part jel or cure? > 2) While I'm not quite as skeptical of your ability to save the part as > Carl Denk is, I think it would be very difficult to sand off the shear > web and leave clean foam below. (snip) I have rejected someone's wing skins and told them to sand them off. This can be done saving the foam and spar that the person made. The wing was saved by this methed. If you can get your glass off, you could do the same as Marc said! In my Cozy 3 that I built. The first tub I made was 2" smaller because of a mistake on a template I MADE using the plans A drawings. I made the front seat bulkhead by trimming the edges too small and did not catch the mistake until I was ready to install the main spar and turtleback. I decided that 2" was too small for me and cut the corect bulkheads out of the tub and started over. The learning curve SUCKS. It took me 5 months to make the first tub and 5 weeks to get back to where I was again. Keep plugging at one part at a time and someday your fly and it's all worth it :-) -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com P.O. Box 7307 Port St. Lucie FL. 34985 Shop# 561-460-8020 Home# 561-343-7366 Composite workshop info: http://www.Sportair.com From: lschuler@cellular.uscc.com Date: Mon, 19 Jan 98 10:59:00 -0600 Subject: Re: COZY: Sticky epoxy Tom Brusehaver wrote: >snip >I assume the layup is junk, but I am wondering if there is a way to >peel it, or something. (probably not). I'd sure be afraid to risk my life on the epoxy you describe. It's your call; but you may be able to heat it up and get it to cure. Even if it seems cured to you eventually, the strength properties would be questionable. If it relly looks like it is wasted, might try taking a dremel cut-off wheel and cut the glass along both top and bottom corners of the shear web. Careful not to cut too deep into the foam. The glass will peel right off the foam taking some chunks of foam with it. If the resulting holes in the foam aren't too big, you can simply fill them with dry micro and do the layup again. Hope this helps. Larry Schuler lschuler@cellular.uscc.com From: Epplin John A Subject: COZY: Construction tip Date: Wed, 21 Jan 1998 08:02:42 -0600 I have found PLY9 protective gel makes a wonderful release agent for epoxy. If you let it dry, it will not migrate onto places you don't want it. I have used it on clecos and threaded fasteners with good success. John epplin Mk4 #467 Date: Wed, 21 Jan 1998 08:16:12 -0600 (CST) From: "Tom G. Brusehaver" Subject: COZY: Sticky Epoxy I sorta took Marc Z's advice and waited. Well, I got busy, and was unable to do anything anyway :-). I had been using one of those cheepo mercury hardware store thermometers to measure my shop temp. It usually said about 72. Yesterday I went downstairs and I could feel a significant tempreature change from main floor of the house to the basement. I looked at the thermometer, and it still said 72. Well, it wasn't 72, unless it was 80 upstairs! I scratched my epoxy samples, and they are hard! My guess is the temprature is in the middle 60's in the basement, and it just is taking that much longer to get the epoxy to setup. I have baseboard heaters in the basement, I think I need to run them a little more. I prefer working in shirt sleeves as opposed to with a sweater anyway. Thanks everyone for the advice. I still have a lot to do on the canard, but at least I have a bunch of other ideas now. I think it wouldn't be that much trouble to build another one. Date: Tue, 20 Jan 1998 20:48:06 -0500 From: Rob Cherney Subject: Re: COZY: Sticky epoxy At 10:59 AM 1/19/98 -0600, lschuler@cellular.uscc.com wrote: >If it relly looks like it is wasted, might try taking a dremel >cut-off wheel and cut the glass along both top and bottom corners of >the shear web. Careful not to cut too deep into the foam. The glass >will peel right off the foam taking some chunks of foam with it. If >the resulting holes in the foam aren't too big, you can simply fill >them with dry micro and do the layup again. If it were my airplane, I'd cut off the foam associated with the entire spar and glue new pieces on the remaining aft section of the wing. The cut line would be along the two aft edges (top and bottom of the wing) of the spar cap trough. The new foam would be roughly a square cross section and could easily be glued to the aft portion of the wing. You could even cut the foam a little big and then sand it down to the correct shape using a long bar. Another alternative is to get some vendor we know (now in Florida) to sell you the molded spar and glue it on. Better yet, get two. Rob- +------------------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@home.com | +------------------------------------------------------------------+ Date: Wed, 21 Jan 1998 16:31:39 +0200 From: Rego Burger Subject: COZY: Sticky Epoxy -Reply I know it's colder there than here but what i have to do in our winter is this, I make a simple shroud around the item out of plastic sheeting...in the form of a "tunnel"..on the input side I place an electric fan heater....you may need two....and I close off the tail end so the haet does not escape. If you do this late at night set the heaters on a time switch for say an hr or two for safety. You don't want to wake up and find a fire going. This consentrates heat energy onto the item you're making instead of heating the room first! Once the surface you wish to place the "tunnel" over has been peel ply'd I put small plastic sheets on the surface with some bottles to lay the "tunnel" over. Once the fan heaters are running it looks like a hot air balloon. PS. use light weight plastic sheet even like the garbage bag type, just tape them to each other for large surfaces. Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za Date: Mon, 23 Feb 98 16:06:08 EST From: "Nick J Ugolini" Subject: COZY: Oil on Fiberglass I recently completed my 3 bladed fiberglass prop and test flew this weekend and of course the raw fiberglass received a christening of oil. Question: Is washing the glass in a good dish detergent, and a MEK wash adequate to clean the oil off? Is there something else I can use to clean the surface? I still have to finish fill (micro) and paint the prop. Thanks Nick Date: Fri, 20 Mar 1998 07:36:49 -0500 From: "Calvin N. Hobbs" Subject: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! Wo ist yer brainentinkschtich? A fundamental question. I have discovered what appears to be a layer of peel ply on a part (instrument panel)I made over one year ago. I tried to "peel" it off. It doesn't want to come. It is clearly imbedded in the green colored epoxy. (Maybe this is the stuff everone has been damning? And I was using it before it's deleterious properties were revealed ) Oops. Do I: A. Sand it off down to the fiberglass, but be careful not to damage the fibre and make sure all the peel-ply is off the edges so there will be an area to make a bond later? B. Remove it with some chemical of which I am unfamiliar? C. "Peel it anyway doofus" because I should have discovered this in the FAQ and don't bother the group with such trivial questions again until you erect and alter to Nat Puffer and burn copies of copy-cat canard brouchures with Mobil 100 Ashless oil? (just kidding Nat, you know I love you) D. Something else _______________________________________________________________________________________ (please fill in) Date: Fri, 20 Mar 1998 08:25:43 -0500 From: Paul Krasa Subject: Re: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! My suggestion is chuck the composite panel and make your panel out of .125" 6061 AL. IMHO the AL panels look better, and is removeable for easy access. Paul At 07:36 3/20/98 -0500, you wrote: >A fundamental question. > >I have discovered what appears to be a layer of peel ply on a part >(instrument panel)I made over one year ago. I tried to "peel" it off. >It doesn't want to come. It is clearly imbedded in the green colored >epoxy. (Maybe this is the stuff everone has been damning? And I was >using it before it's deleterious properties were revealed ) Oops. > >Do I: >A. Sand it off down to the fiberglass, but be careful not to damage the >fibre and make sure all the peel-ply is off the edges so there will be >an area to make a bond later? >B. Remove it with some chemical of which I am unfamiliar? >C. "Peel it anyway doofus" because I should have discovered this in the >FAQ and don't bother the group with such trivial questions again until >you erect and alter to Nat Puffer and burn copies of copy-cat canard >brouchures with Mobil 100 Ashless oil? (just kidding Nat, you know I >love you) >D. Something else >___________________________________________________________________________ ____________ > >(please fill in) > > > > From: Jim Hocut Subject: RE: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! W Date: Fri, 20 Mar 1998 05:44:28 -0800 > Calvin N. Hobbs wrote: > I have discovered what appears to be a layer of peel ply on a part > (instrument panel)I made over one year ago. I tried to "peel" it off. > It doesn't want to come. It is clearly imbedded in the green colored > epoxy. (Maybe this is the stuff everone has been damning? And I was > using it before it's deleterious properties were revealed ) Oops. > > I had a similar problem a while back with some "peel" ply that wouldn't peel (lesson learned - when you go to the fabric store make sure you buy 100% nylon lining material and nothing else). > Do I: > A. Sand it off down to the fiberglass, but be careful not to damage > the > fibre and make sure all the peel-ply is off the edges so there will be > an area to make a bond later? > That was the only thing I could think of that made sense. It was a bit of work (punishment) but after I put in my time with the sanding block all was well. Jim Hocut jhocut@mindspring.com From: ponciroli@postoffice.worldnet.att.net Date: Fri, 20 Mar 1998 15:16:52 -0500 Subject: Re: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! >A fundamental question. > >I have discovered what appears to be a layer of peel ply on a part >(instrument panel)I made over one year ago. I tried to "peel" it off. >It doesn't want to come. It is clearly imbedded in the green colored >epoxy. (Maybe this is the stuff everone has been damning? And I was >using it before it's deleterious properties were revealed ) Oops. > >Do I: >A. Sand it off down to the fiberglass, but be careful not to damage the >fibre and make sure all the peel-ply is off the edges so there will be >an area to make a bond later? >B. Remove it with some chemical of which I am unfamiliar? >C. "Peel it anyway doofus" because I should have discovered this in the >FAQ and don't bother the group with such trivial questions again until >you erect and alter to Nat Puffer and burn copies of copy-cat canard >brouchures with Mobil 100 Ashless oil? (just kidding Nat, you know I >love you) >D. Something else >_______________________________________________________________________________ >________ > >(please fill in) I have had good success with heat as mover of epoxied items, try a heat gun and try to remove it. If that fails then I would sand it a little and try the heat again. It should come off. I can't resist the temptation of pulling off the peal ply as soon as I can, How can you resist? Don Ponciroli ponciroli@att.net From: SBLANKDDS Date: Fri, 20 Mar 1998 17:09:01 EST Subject: Re: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! Wo ist yer brai In a message dated 98-03-20 , Don Ponciroli wrote: << I have had good success with heat as mover of epoxied items, try a heat gun and try to remove it. If that fails then I would sand it a little and try the heat again. It should come off. I can't resist the temptation of pulling off the peal ply as soon as I can, How can you resist? >> Bad idea to pull peel ply before a complete cure. "As soon as I can"...can mean a lot to different people. If you pull it before the complete cure (verified with nail scratch on left over resin), you may weaken the bonds between layers. Be careful how you say things to people that are new to this stuff. BUT it is fun to pull. For more fun, after complete cure, separate the peel ply in the dark, great glow from the static electricity produced!!!!!! Steve Blank Cozy Mark IV #36 web site -----> Cozy Mark IV Date: Sat, 21 Mar 1998 06:29:10 -0500 From: bil kleb Subject: Re: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! ponciroli@postoffice.worldnet.att.net wrote: > > I can't resist the temptation of pulling off the peal ply > as soon as I can, How can you resist? you mean you don't follow burt's rule of leaving the peel ply in place until just before you are going to: 1) wipe the surface with a damp cloth (the only way to be rid of amine blush and only necessary if you're using 2427), 2) sand with 40 grit, and 3) do a secondary bond to the surface? :) -- bil Date: Mon, 23 Mar 1998 18:57:04 +0000 From: Paul Kuntz Subject: Re: COZY: Ist das Peel Ply? Ja, das ist peel ply you dumkoff! Wo ist yer brainentinkschtich? Calvin N. Hobbs wrote: > > A fundamental question. > > I have discovered what appears to be a layer of peel ply on a part > (instrument panel)I made over one year ago. I tried to "peel" it off. > It doesn't want to come. It is clearly imbedded in the green colored > epoxy. (Maybe this is the stuff everone has been damning? And I was > using it before it's deleterious properties were revealed ) Oops. > > Do I: > A. Sand it off down to the fiberglass, but be careful not to damage the > fibre and make sure all the peel-ply is off the edges so there will be > an area to make a bond later? > B. Remove it with some chemical of which I am unfamiliar? > C. "Peel it anyway doofus" because I should have discovered this in the > FAQ and don't bother the group with such trivial questions again until > you erect and alter to Nat Puffer and burn copies of copy-cat canard > brouchures with Mobil 100 Ashless oil? (just kidding Nat, you know I > love you) > D. Something else > _______________________________________________________________________________________ > > (please fill in) I had this problem on one of my bulkheads, using some polyester cloth that was the right price, but turned out to be made of too fine a weave. It tended to get embedded in the epoxy as you describe, and was the devil to peel off. One bulkhead simply refused to peel at all because the cloth was embedded in the epoxy to the point where I couldn't get hold of an edge to start the peel. I borrowed a friend's random orbital sander to see how it would work. As it turned out, it was very easy to sand down to the peel ply and get it to ball up and come off without going into the glass cloth at all. It took awhile, but was easier than building the whole bulkhead again. Paul Kuntz Cozy Mk IV #003 England From: EGStrong Date: Wed, 1 Apr 1998 00:56:20 EST Subject: COZY: Delamination repair I am in the "bought the info package, thinking about buying the plans" stage. I am trying out the composite practice kit and completed the confidence layup with the beam, then broke it in half per the instructions in order to do the repair. My problem is that I apparently didn't add enough micro before laying the glass on the foam and left some air between the glass layers, so when I broke it in half the top and bottom layers separated from each other for most of the beam length. No big deal except it brought up the question of how to repair delaminations. Do I simply put some epoxy between the layers and clamp them together or do i need to sand them both down first, or do I have to trash the part? I am more worried about what to do if it happens during a Cozy buildup than on my practice beam. From: "William Drexler" Subject: COZY: Protecting Foam Date: Mon, 27 Apr 1998 19:52:54 -0600 Hello: How has everyone been protecting their foam during layups? I have done a few bulkheads but while I do the layup (on the frontside of a bulkhead for example), the epoxy runs onto the bench and pools enough to wreck the edges and back sides of the yet unglassed foam. I have tried masking tape, wax paper, elevating the foam on foam blocks, etc., but I am still managing to cause damage. Then, my next question is what do you do to fix the damaged foam? It is my understanding that the slurry is used to fill the broken cells on the surface of the foam pieces. If I have unintentionally epoxied areas on the surface, how do I prep the surface before glassing. Do I only need to sand those areas and glass right over them, or do I need to dig into the foam and remove those damaged areas and then patch it with dry micro, etc.? Thanks for the info. Will Drexler drexler-william@usa.net From: ponciroli@postoffice.worldnet.att.net Date: Tue, 28 Apr 1998 09:08:00 -0500 Subject: Re: COZY: Protecting Foam Will Drexler wrote: the epoxy runs onto the bench and pools enough to wreck the edges and back sides of the yet unglassed foam. AND If I have unintentionally epoxied areas on the surface, how do I prep the surface before glassing. Will - I'm trying to understand your question. If you exopy the foam with a slurry and lay the glass over the slurry, the epoxy wont go anywhere. You then wet out the glass and squeege the extra epoxy out of the layup. any epoxy that runs over the side can be wiped up. any epoxy that gets into the foam can be left there until you do the other side. Just because the epoxy gets on the foam before you are ready for layup doesn't mean that it is ruined. The main reason for the slurry is to migrate the epoxy and baloons into the layup to attach the glass to the foam core and at the same time conserve weight. The little you spill around the edges is incidental. Just try to be neat and apply only that which you are able to control. As for the second question: Just sand the surface even and start to glass the reverse side. Don Ponciroli ponciroli@att.net From: lschuler@cellular.uscc.com Date: Tue, 28 Apr 98 09:00:42 -0600 Subject: Re: COZY: Protecting Foam William Drexler wrote: >How has everyone been protecting their foam during layups? I have done a >few bulkheads but while I do the layup (on the front side of a bulkhead for >example), the epoxy runs onto the bench and pools enough to wreck the edges >and back sides of the yet unglassed foam. I have tried masking tape, wax >paper, elevating the foam on foam blocks, etc., but I am still managing to >cause damage. >snip The way I do it is to glass an over size piece. The edges get wasted in the process and the leaky epoxy gets cut off. After cure, I cut very close to shape with a band saw and finish to the line(s) with sanding block. I have traced all drawing templates to a throw-away sheet of paper. [ I haven't actually thrown many away yet.] I use double-sided Scotch (or whatever) tape to hold the template on the sheet to be cut, overlapping the cut line with the tape here and there to keep the paper from moving around while cutting on the band saw. Works for me. Waste a bit of epoxy and glass, but seems a lot neater and don't need to worry about getting up early in the morning to do knife-trimming etc. Larry Schuler Plans #500 ch-13 lschuler@cellular.uscc.com Date: Tue, 28 Apr 1998 11:51:11 -0400 From: greg_piney@mcgraw-hill.com (greg_piney) Subject: Re: COZY: Protecting Foam Sounds like you are overwetting the glass on a large scale. Wet from the center out to the edges. Use a stippling brush and squeegee to move the epoxy around. Make sure you have no trapped air. You should move epoxy to no more than an inch beyond the edge of the foam. Use the squeegee to pickup and remove excess epoxy. Greg Piney William Drexler wrote: > Hello: > > How has everyone been protecting their foam during layups? I have done a > few bulkheads but while I do the layup (on the frontside of a bulkhead for > example), the epoxy runs onto the bench and pools enough to wreck the edges > and back sides of the yet unglassed foam. I have tried masking tape, wax > paper, elevating the foam on foam blocks, etc., but I am still managing to > cause damage. > > Then, my next question is what do you do to fix the damaged foam? It is my > understanding that the slurry is used to fill the broken cells on the > surface of the foam pieces. If I have unintentionally epoxied areas on the > surface, how do I prep the surface before glassing. Do I only need to sand > those areas and glass right over them, or do I need to dig into the foam > and remove those damaged areas and then patch it with dry micro, etc.? > > Thanks for the info. > > Will Drexler > drexler-william@usa.net From: lschuler@cellular.uscc.com Date: Tue, 28 Apr 98 11:03:23 -0600 Subject: Re[2]: COZY: Protecting Foam I wrote: >The way I do it is to glass an over size piece. >snip I forgot to mention, and I think this is important, that where I don't have enough foam/glass that is waste-able around the edges, I have done one of two things: 1. Glass one side; cover with peel ply; cover that with plastic; flip it over [very carefully to keep the glass from flopping off]; and, glass the other side. Waiting an extra hour or two before flipping it over helps keep the glass in place as well. 2. Where #1 isn't practical or do-able (which creates the "leakage" issue), I lay a strip of peel ply around the edge between the table (covered with plastic of course) and the foam. This helps to ensure that where the epoxy 'does' leak, the peel ply will provide a good bonding area without trying to sand it rough and gouging out the adjoining soft foam. When I vac bag, I modify the above a bit; but, that's another story. Hope this helps. Larry Schuler Plans #500 ch-13 lschuler@cellular.uscc.com From: "Nat Puffer" Subject: Re: COZY: Protecting Foam Date: Tue, 28 Apr 1998 12:47:17 -0500 Dear Cozy builders, Just a caution about trimming fiberglass layups on your bandsaw. Fiberglass ruins band saw blades in a hurry, so they are no good for cutting aluminum or anything else. Better to use a sabresaw. I take my old bandsaw blades and cut them into short strips that I can use in my sabresaw. I then throw them away after cutting fiberglass. Best regards, Nat Date: Tue, 28 Apr 1998 16:22:17 -0400 From: bil kleb Subject: Re: COZY: Protecting Foam Nat Puffer wrote: > > Just a caution about trimming fiberglass layups on your bandsaw. > ... Better to use a sabresaw... warning about using a sabre saw: it's motion is both up and down, instead of purely downward as with the bandsaw. i found that unless you are very careful in securing the layup, that the sabre-saw motion can delaminate the edges of layups due to the upward stroke. -- bil From: Bes1612 Date: Tue, 28 Apr 1998 16:46:49 EDT Subject: COZY: Exotherm Howdy builders: I was wondering how one could tell if there was exotherm damage? I connected my winglet the other day. Did the #1 layup, which is 8 plys bid, and wedges of foam and flox filling any voids. Instuctions include the admonition to allow it to partially set befor going to #2, which is 8 more plys of bid and a foam block "A" set on top of that with flox filling voids. I gave each layup a couple of hours. It was a warm day, (Finally, the epoxy flows so nice when its warm.) and I thought that would be enough time. But I could feel a good deal of heat on the surface of the wing and winglet from the layup. It was definitely warm to the touch, though nothing near hot. I do not know how to tell if damage was done. Or if I gave it enough time to "set partially". Everything looks and feels fine. Is there something that may not be evident? Would the glass allow you to see the damage. Or will it need to be x-rayed? What say ye? Bob Smith From: Marc J. Zeitlin Subject: COZY: Exotherm Date: Tue, 28 Apr 98 20:20:38 EDT Bob Smith writes: >I was wondering how one could tell if there was exotherm damage?...... >......It was >definitely warm to the touch, though nothing near hot. I do not know how to >tell if damage was done. Or if I gave it enough time to "set partially". >Everything looks and feels fine. Is there something that may not be evident? Remember that you can post cure these epoxies in the 140 F to 180 F range (or more - I forget) and that the glass transition temperature after post cure can be in the 200 F range. If you could touch the layup and not get burned, you didn't harm the glass. Mostly, the "exotherm" issue is one of hurting the foam (IIRC) not the glass. If the layup didn't get hot enough to burn you (which would be extremely unlikely even on a middling thick layup), then the chance that you did any damage to either the layup or the foam is extremely small. I can imagine an exotherm on a thick spar cap layup, maybe, or in the 90 layer thick landing gear attach point layups (chapter 9), but on any large flat layup the surface area to volume ratio is so high that it would have to be REALLY hot to support a real exotherm, not just a localized "warming". I had some Safety-Poxy exotherm on me once when I did a large mix (maybe 6 oz or so) in a 115 F workspace - I had to drop the cup of epoxy on the floor because it started to burn my hand through the glove. The epoxy went from liquid to solid in about 5 seconds. THATS an exotherm :-). -- Marc J. Zeitlin Email: marcz@an.hp.com From: Jim Hocut Subject: RE: COZY: Exotherm Date: Tue, 28 Apr 1998 20:59:17 -0400 Marc Z. wrote: Remember that you can post cure these epoxies in the 140 F to 180 F range (or more - I forget) and that the glass transition temperature after post cure can be in the 200 F range. One caution that maybe should be pointed out here.... The limitation we have with post cure temperatures is that most of the foams we use will melt above about 150 F or thereabouts. So of course keep temperatures a safe margin below this. Jim Hocut jhocut@mindspring.com From: "Alpha Computer Systems" Subject: RE: COZY: Exotherm Date: Wed, 29 Apr 1998 17:59:23 -0400 Why not change to some of the more heat resistant/fire proof foams....also more dent resistant? I know they cost a bit more but it would seem to be better but I'm no engineer. Wouldn't that also allow one to paint the plane any color without fear of weakening the structure due to heat build-up (if one post cured the layups? What about it ? What do you think? Jim Brewer Albemarle, NC Date: Wed, 20 May 1998 13:45:18 -0500 From: Tom Brusehaver Subject: COZY: Mirco Balloons (glass bubbles) I hate 'em! Anyone have a good way to handle them? They get everywhere. I am wearing a mask always (usually?) when I handle 'em. But, they just get on the floor, in the mix you don't want 'em in, I still sneeze when I get done. I have decided my loathing is what causes delays of building. If I know I gotta mix up a batch of slurry, I stall until I can run out of excuses, and then I just do it. Date: Sat, 30 May 1998 22:21:46 -0400 From: Ian Douglas Subject: COZY: Mixing Micro Hello All, I thought that I might share a method of mixing micro with any of the newbees out there. I know that when I first started, a large amount was landing on the table or floor. My first method to reduce spills was to mix in smaller amounts at a time (this took for ever to get it mixed). I now have a sure fire way and even dry micro will be mixed in less than 50 revolutions... Get a putty knife that covers a little over half the diameter of your mixing cups. Move the putty knife back and forth so that the sharp edges are hitting each side of your cup (like you are cutting the contents up). Add a half inch movement at each side so that you are now making an oval (like a race track). By fifty laps your micro will be mixed. As it starts to ball up (around 35 laps) take the knife and scrape around the edge forcing the contents to the middle. Go back to the race track pattern. With this technique I am able to mix up dry micro in under a minute (about 50 secs) and not spill of cause any micro dust in the process. -- Best regards, Ian D.S. Douglas Cozy MKIV 0069 From: "Hunter GA (Gary) at MSXSCC" Subject: RE: COZY: Glassing Upside Down Date: Fri, 12 Jun 1998 14:46:40 -0500 Steve, Do the layup on a piece of thin polyethylene painters drop cloth (or some sort of thin clear plastic film) on top of the bench. Then transfer it (plastic and all) to the location on the airplane and squeegy into place. Make sure the area on the airplane you are laminating onto is pre-wetted with a little of the mixed resin before applying the pre-wetted layup. The clear plastic allows you to see what you are doing while handling and placing the pre-wetted laminate. After the laminate is put in place, you can peel away the Poly and allow it to cure. Gary Hunter EAA Technical Counselor Vari-Eze - N235GH gahunter@shellus.com > ---------- > From: Steve Campbell[SMTP:campbell@ece.umn.edu] > Sent: Friday, June 12, 1998 7:36 AM > To: cozy_builders@canard.com > Subject: COZY: Glassing Upside Down > > As I start to assemble some of the little airplane bits and pieces into > big > airplane bits and pieces, I am running into a problem that I hope some of > you can help me with. In some cases it seems quite difficult avoiding > having part of the layup on the bottom of a structure. If it is a small > layup (1 layer, short distance), I usually don't have a problem. Last > week > trying to work on the wing ribs I had 3 plies of BID and I could not get > it > to stick to the underside of the wing skin. Any advice gratefully > appreciated. BTW, I am using Aeropoxy if that makes any difference. > Thanks > Steve > ************************************************ > Stephen A. Campbell, Professor, ECE > University of Minnesota > 200 Union Street Minneapolis 55455 > (612) 625-5876 phone / (612) 625-4583 fax > Campbell@ece.umn.edu > ************************************************* > Date: Fri, 12 Jun 1998 12:25:18 -0800 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: Glassing Upside Down >Last week >trying to work on the wing ribs I had 3 plies of BID and I could not get it >to stick to the underside of the wing skin. Any advice gratefully >appreciated. BTW, I am using Aeropoxy if that makes any difference. >Thanks >Steve Steve, I am not familiar with Aeropoxy, but I can make one suggestion that MAY help. I have had pretty good luck with wetting out the glass plys on a piece of aluminum foil (the heaviest foil you can find) on the bench. Actually, it works better with TWO pieces of foil, overlapping a bit, because that makes it easier to peel them off later. You can draw sort of a pattern on the foil with a felt tip, then cut to the line after all squeegy work is done. Now pick up the whole thing, and slap it up under your wing/ribs/whatever, and stick it down (up?) well. If it's large, an extra pair or more of hands may be very helpful. Use a brush to continually press it back in place, as you carefully peel the foil off. Glass/epoxy ratio is already perfect, and there is a minimum of fussing to do, after it is in place. Just stipple it well, and voila! --Howard Rogers, 650-926-4052 hrogers@slac.stanford.edu From: David de Sosa Date: Wed, 1 Jul 1998 15:06:08 -0700 My project has been stored for the last 3 years and I am concerned about the dust and grime which has accumulated on the exposed foam surfaces. What is the best way to clean exposed urethane with grease spots and dust build up on it? Also, what is the best way to clean off 3 year old dust and grime on all epoxy covered surfaces without contaminating them prior to micro filling? David de Sosa Cozy MK-IV #080 d-desosa@ti.com From ???@??? Wed Jul 15 00:10:48 1998 Received: from twc2.betaweb.com (betaweb.com [206.43.209.18]) by strato-fe0.ultra.net (8.8.8/ult.n14767) with ESMTP id WAA31101 for ; Tue, 14 Jul 1998 22:55:41 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id WAA08444 for cozy_builders-list; Tue, 14 Jul 1998 22:42:33 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from m16.boston.juno.com (m16.boston.juno.com [205.231.101.192]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id WAA08439 for ; Tue, 14 Jul 1998 22:42:28 -0400 Received: (from dhill36@juno.com) by m16.boston.juno.com (queuemail) id DH6SEFG2; Tue, 14 Jul 1998 22:37:25 EDT To: cozy_builders@canard.com Date: Tue, 14 Jul 1998 22:40:11 -0400 Message-ID: <19980714.224011.3598.0.dhill36@juno.com> X-Mailer: Juno 1.49 X-Juno-Line-Breaks: 0,6,9-17 From: dhill36@juno.com (Dana Hill) Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: dhill36@juno.com (Dana Hill) X-UIDL: 77fd6054a077aae2efb70d4dce897407 Hi all- I would like to find out what the difference is between two types of prefab. laminate: G-10 and FR-4. Apparently the FR-4 is just like the G-10 except it has a fire retardant. Some builders have used the G-10 and I was wondering if the FR-4 would be OK. It sounds like a little fire retardant would be a good thing-- yes? The souce I found in MA has only FR-4. Also, I don't have the plans with me and was wondering if one of you would know what the approx. quanity needed is for either Ch 4/5 or the entire cozy. Thanx for any help. _________________________ Dana Hill CZ Mk IV, #676 Ch. 4 I _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] Date: Tue, 14 Jul 1998 23:08:29 -0400 From: Rob Cherney Subject: COZY: Re: At 10:40 PM 7/14/98 -0400, Dana Hill wrote: > I would like to find out what the difference is between two types >of prefab. laminate: G-10 and FR-4. Apparently the FR-4 is just like >the G-10 except it has a fire retardant. I think the FR-4 is fungus resistant. It is used to make circuit boards for humid environments. Otherwise, it is more or less the same stuff. Rob- +------------------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@home.com | +------------------------------------------------------------------+ Date: Wed, 15 Jul 1998 00:20:18 -0400 From: "Marc J. Zeitlin" Subject: Fwd: COZY: Re: Rob Cherney writes: >I think the FR-4 is fungus resistant. It is used to make circuit boards >for humid environments. Otherwise, it is more or less the same stuff. I'm pretty sure Dana had it right - the FR is "fire retardant", not "fungus resistant". At least, that's what it always meant when we spec'ed it on our drawings :-). It's merely more expensive, and has even more toxic chemicals in it, but since it's already cured, you don't care :-). -- Marc J. Zeitlin                     marcz@burnside.ma.ultranet.com 3 Sweetbriar Way                  http://www.ultranet.com/~marcz Acton, MA  01720                 http://cozy.canard.com/ From: Chm12345@aol.com Date: Thu, 27 Aug 1998 19:46:42 EDT Subject: COZY: Intrument panel stiffeners ribs and other Qs Hi all, My question is: to flox corner or not to flox corner?. In the instrument panel stiffeners, were the two lay-ups come together at 90 deg, should I flox corner this area?. The first answer that comes to my mind is yes and I actually did in one of them. My question arises because by the time you radius the .2" stiffener there is not much meat left to do a flox corner. I also got an air bubble at one place at the top radius on the 2 BID side. I tried hard to make it lay down but to no avail. I had enough radius but I wonder if the radius is not consistent whether this could cause the fibers to separate slightly. Is this something I'll have to deal with often are this ribs particularly tricky?. One last question. A couple of weeks ago I got a slight burning sensation in my forehead and checks after doing a lay-up. No rash and no redness but it was noticeable. My garage is poorly ventilated because I'm running an AC unit to keep the temperature and humidity under control. I am correcting this now by ventilating my garage better. I use gloves and ply9 cream. I haven't used a respirator although I'm also correcting that. Is a slight skin reaction from over-exposure to the epoxy normal or is this a sign that I should stop thinking I'll be able to build this airplane because of epoxy sensitivity?. Thanks for the feedback. Chris Martin Date: Mon, 31 Aug 98 19:26:11 +0000 From: cac@exo.com@exo.com Subject: Re: COZY: kevlar over carbon "bil kleb" asked: > a few months ago, there was mention of kelvar fibers over carbon fibers > being a bad combination. the reasoning was something like: kevlar > survives the impact but the carbon underneath shatters. In fact the rubber bandit uses kevlar over their carbon fiber fuslage to contain the carbon fiber slivers in case of rubber band failure. They said it acts as a bag to hold in the slivers. Try www.rubberbandit.com ////////////////////////////////////////////////////////////////////////////// // // // Cliff A. Carpenter // // // ////////////////////////////////////////////////////////////////////////////// From: "L. Wayne Hicks" Subject: RE: COZY: kevlar over carbon Date: Tue, 1 Sep 1998 10:07:50 -0400 -----Original Message----- From: bil kleb [SMTP:w.l.kleb@larc.nasa.gov] Sent: Monday, August 31, 1998 4:23 PM To: cozy_builders mailing list; canard-aviators@canard.com Subject: COZY: kevlar over carbon a few months ago, there was mention of kelvar fibers over carbon fibers being a bad combination. the reasoning was something like: kevlar survives the impact but the carbon underneath shatters. can anyone point me to the original study or reference for this? -- bil [L. Wayne Hicks] I believe Paul Krasa spoke earlier on this subject. He cited a NASA study which indicated the results from above. Date: Tue, 1 Sep 1998 10:28:34 -0500 (CDT) From: Steven A Eberhart Subject: RE: COZY: kevlar over carbon THis is only related to the topic but I am using a kevlar cocoon sourounding the passenger compartment specifically to keep the carbon fiber from the fuselage structure and any assorted tree limbs, etc. that might try to gain entry into the cockpit where they belong - on the outside. My plane is a new design, not a canard but I like the idea of the extra protection provided by the kevlar. I really haven't been able to come up with any other good uses for it in the plane though. Steve Eberhart --------------- http://www.newtech.com/nlf For a family of new laminar flow airfoils On Tue, 1 Sep 1998, L. Wayne Hicks wrote: > > > -----Original Message----- > From: bil kleb [SMTP:w.l.kleb@larc.nasa.gov] > Sent: Monday, August 31, 1998 4:23 PM > To: cozy_builders mailing list; canard-aviators@canard.com > Subject: COZY: kevlar over carbon > > a few months ago, there was mention of kelvar fibers over carbon fibers > being a bad combination. the reasoning was something like: kevlar > survives the impact but the carbon underneath shatters. > > can anyone point me to the original study or reference for this? > > -- > bil > > [L. Wayne Hicks] I believe Paul Krasa spoke earlier on this subject. He cited a NASA study which indicated the results from above. > > Date: Mon, 07 Sep 1998 17:16:12 -0500 From: "Joseph H. Hart IV" Subject: COZY: How Good is Good? Well, despite a prediction last January that I was about to begin building, finances and time resulted in the big day being postponed eight or nine months. This weekend, after having received my first batch of materials from Wicks, I built the GIANT table and glass cutting stand and took the big leap. I've read the instructions and watched Rutan's video countless times and I've completed the practice lay-ups. I just finished the two UNI lay-ups for the seat back bulkhead and am left with the question of "How good is good?" Specifically, how straight do the fibers need to be? In the video, Mike Melville doesn't spend much time straightening the fibers. When I emulated him, my fibers where relatively straight but wouldn't hold up to a straight-edge. In fact, while matching up the selvage edges, I had to manipulate the edges to get them to butt against one another. I never could get the edges to be perfectly straight but did get the two pieces of cloth to ultimately be very close. I'm using the MGS 285 resin and mixing the fast and slow hardeners fifty/fifty. How much excess epoxy should be removed? What I ended up doing was squeegied until I no longer got a ridge of epoxy and then squeegied a little bit more. Was this the right approach? With regard to the micro slurry, is it supposed to be thick enough to fill in each of the little pores of the PVC or just fill in more major imperfections in the foam? Finally, if I've screwed up by not having the fibers straight enough or by not using enough micro, do I need to start over again or is this particular part, or even this process, more forgiving than that? I suspect that I am experiencing beginners paranoia and that everything is fine, but I thought I'd throw these questions out to make sure that I have committed any heinous errors. Despite religously reading the postings and reviewing the archives, beginning this project remains somewhat intimidating! Thanks for any advice/words of encouragement that you can provide. Jody Hart jodyhart@cmq.net Date: Mon, 07 Sep 1998 17:28:16 -0500 From: "Joseph H. Hart IV" Subject: COZY: More How Good is Good? A few more that I left out: Because of the recent posting regarding the MGS 285 hardener reacting with the plastic of the Sticky-Stuff dispensers, I bought the electronic postal scale from AS&S. The scale is accurate w/in .1 oz. or 2 g. I've been mixing batches ranging from 50 to 100 g. of hardener to the appropriate amount of resin. My questions is whether this scale is accurate enough for my use? If I mix a batch of 50 g. resin to 20 g. hardener, the amount of hardener could be off by as much as 2 g. or ten percent. Am I asking for trouble? For those of you starting after me, a few things to know: A little five-minute epoxy goes a looooong way. I am afraid of what the back of my seatback is going to look like when I pry it off the table! I didn't have as good of luck with the Invisible Gloves as I had hoped. I don't know if it has to do with the MGS or not, but I will definitely be purchasing some "visible" gloves for the next lay-up. Thanks again. Jody Hart Date: Mon, 7 Sep 1998 19:53:17 -0400 From: siegler@charm.net (Stuart Siegler) Subject: Re: COZY: More How Good is Good? >accurate enough for my use? If I mix a batch of 50 g. resin to 20 g. >hardener, the amount of hardener could be off by as much as 2 g. or ten >percent. Am I asking for trouble? Its a drag using the scale when you need lots of epoxy. And you need more than 100g for just about everything (at least for a while). The dispenser will save you much time (imho). > > For those of you starting after me, a few things to know: > > A little five-minute epoxy goes a looooong way. I am afraid of what >the back of my seatback is going to look like when I pry it off the >table! Use a plastic sheet, especially on the layups. I forgot this a glued 4 bulkheads to my table. After chisling them off, flipping the table top, and rebuilding the bulkheads, I vowed never to forget this again. Another tip: Keep your cutting shears sharp. You have no idea how painfull it is to have a layup "ruined" because you pulled the fibers instead of cutting them. Stuart -- Stuart Siegler siegler@charm.net http://www.charm.net/~siegler/ ... and we're gonna keep on having meetings 'till we find out why nothing's getting done here. Date: Mon, 07 Sep 1998 22:51:17 -0400 From: "Marc J. Zeitlin" Subject: Fwd: COZY: How Good is Good? Joseph H. Hart IV writes: >.........."How good is good?" The eternal question. I believe there are some religious texts that spell this out. . . oh - you meant with respect to building airplanes :-). This is one of the few things that bugs the heck out of me as an engineer, with respect to the plans (the COZY plans, the RAF plans, and the Quickie plans, all of which I've studied and are derived from the same sources). There are very few places where tolerances are called out. > Specifically, how straight do the fibers need to be? You won't ever get them perfect (but you should try for a while before giving up). Check out the picture on page 25-2. Just a basic indication to avoid "crooked" fibers. Basically, what it boils down to is that it's more important for the fibers to be straight along their length than to be at exactly the right angle (although that's important too). You can reasonably easily straighten the BID or UNI fibers by pulling gently on either end of them before adding the epoxy. I was able to place and straighten all the glass for each wing skin (a LOT of glass) in less than one hour; straightening the glass for a bulkhead shouldn't take more than a couple of minutes. It doesn't have to be "straight-edge" straight, but make sure it doesn't look like the right hand picture at the bottom of 25-2. >.... How much excess epoxy should be removed? All of it :-). >..... What I ended up >doing was squeegied until I no longer got a ridge of epoxy and then >squeegied a little bit more. Was this the right approach? Yup, but I'll bet $10K that you can still get more epoxy out of the layups (at least with the EZ10/84, anyway). I use a hair dryer and a squeegee AFTER applying the peel ply, and find that I can get lots more epoxy out without getting any air entrainment. The hair dryer lowers the viscosity of the epoxy, and the peel ply ensures that the squeegee (use slowly) will not pull the glass fibers as well as helping to prevent air introduction. > With regard to the micro slurry, is it supposed to be thick enough >to fill in each of the little pores of the PVC or just fill in more >major imperfections in the foam? Fill every last one of them. Add enough micro so that the slurry is very thick and hurts your wrist to apply with a squeegee - any thinner and you're going to have more epoxy than you should and your layup will be heavier. Realize that laying glass up over this while the micro is uncured will suck some epoxy out of the glass and into the micro, making your layup a little dryer - you may want to wait until the micro starts to kick (assuming that you're using an epoxy that will bond to itself well under those conditions - 2427 wouldn't) or even until the micro cures completely (called hard-shelling) before laying up the glass. At any rate, make it as thick as you can spread it. > Finally, if I've screwed up by not having the fibers straight enough >or by not using enough micro, do I need to start over again or is this >particular part, or even this process, more forgiving than that? Use the checking criteria in chapters 3 and 25 and judge for yourself. I'll bet you're fine, but make sure to familiarize yourself with the look of layups you should have - go check out other people's layups to see what they're willing to put up with. > I suspect that I am experiencing beginners paranoia and that >everything is fine....... You betcha. Also, I agree with Stuart Siegler that you should get a pump that's compatible with your epoxy - I personally would never go back to using a scale. -- Marc J. Zeitlin                     marcz@burnside.ma.ultranet.com 3 Sweetbriar Way                  http://www.ultranet.com/~marcz Acton, MA  01720                 http://cozy.canard.com/ Date: Tue, 08 Sep 1998 10:40:08 +0200 From: Rego Burger Subject: COZY: How Good is Good? mmm... Here we will have as many opinions as builders but if you take the average and stick to the "norm" you should be O.K. Fibers: Re: Fibre straightness.... some guys will get a laser gun sight and make them as straight as an arrow. Others like me will eye-ball it and if your eye can catch the fact that it is out by .000001" it's O.K. Marc is correct the fibers must not be wavy.... under compression a slightly skew fibre will "give" long before a straight one. A distorted bunch of fibers concentrated on one spot is like a knot in wood...No good! The nice thing about glass is you can pull it straight while wet. Slurry: Slurry is just that "Slurry" if you place it on an inclined surface +/- 30deg angle it will move down like lava...slow but sure.... Dry micro will hang on the ceiling if you flipped a blob up there. If you make slurry too thick you will work much harder to spread it. If you looked at Burts video they spread the slurry pretty easy! Wipe/ wipe done. +/- 50/50 by volume micro - resin. In my early days I was anti-weight mad and made my slurry a bit too thick ( dryish ). On some of my off - cuts I found that the skin pulled apart from the foam too easy for my liking...and it WAS NOT HARD SHELLED.... it was a chemical bond, just too dry on the slurry. If you use to dry a mix to fill the pores in the foam you will have a light but slightly weaker structure....( too late on some of my parts ) Those pores are like 100's of foundations...they form shear spikes...100's of them if done correctly (slurry) make a super strong bond. ( This is many mistakes later, experience talking! ) Wetting: Wetting out that glass is often another concern.... the "Not Wet Not White" rule still applies. I found a glance at an angle to the surface with light in the background worked well for that final check before bed-time after doing a late lay-up. In figures what you want to try to achieve is a 50/50 resin to cloth weight ratio.... this can only be analyzed afterwards in a lab so again the trained eye must do. Test samples are a good thing.... cut three identical squares say 12"x12" of bid to practice with. Lay out on some plastic sheet on the table and pour 5ml of resin on one and 10ml on the other and 15ml on the third. Spread with a small squeegee and see the effects after cure.... The one with that bright glossy finish is too heavy.... the one you barely could wet out is a little starved and the mid one is about right. Once you are happy with an estimated vol. per area of cloth used as a guide write it down somewhere....it will come in handy for those small jobs....and you will waste less resin when mixing in future when you have a rough figure to work with. Over 6 yrs I have only wasted less than 2% by vol. of resin. What did I do with those left-overs in the cups? Well I mixed dry micro and filled in areas that I was certain would no longer require any more lay up on... e.g. the arm-rests, head rests, the belly of the fuselage. Figures quoted are examples only.... test for yourself and keep a record for Reference. Happy Building. Rego Burger Web site: http://home.intekom.com/glen/rnb.htm e-mail home- mailto:rnb@intekom.co.za RSA Date: Tue, 08 Sep 1998 11:38:53 -0400 From: bil kleb Subject: Re: COZY: More How Good is Good? Joseph H. Hart IV wrote: > > [...] I bought the electronic postal scale from AS&S. The scale is > accurate w/in .1 oz. or 2 g. I've been mixing batches ranging from 50 > to 100 g. of hardener to the appropriate amount of resin. My questions > is whether this scale is accurate enough for my use? IMHO i would say, that it your scale is not accurate enough for batches that small (say anything under 150 g total for your mixing ratios). ten percent is out there... i have a acculab v4000 (4000g/1g) from http://www.balances.com/ that i don't like to use for batches below 100g... -- bil Date: Tue, 8 Sep 1998 08:39:09 -0500 From: Tom Brusehaver Subject: Re: COZY: Selvedge UND >Have I committed a cardinal sin by removing the selvedge from the UND. >I have not yet done the layup so can easily cut some more, but it >appears to me that I will be able to get the edges much straighter with >the selvedge no longer there. I don't think you hurt anything, the fibers are strong going the long way, any of the cross fibers only provide limited additional strength. They really help the stuff from fraying, so make the layup easier. How much selvedge was there? The UNI I get has virtually none. BTW, the last roll of BID I got from Wicks had a different edge. No selvedg that I could detect. It is like they ran a sharp knife down it and spit things open. It was a little frayed, so I assume they wanted it that way, like maybe it isn't necessary to cut it off? Date: Tue, 08 Sep 1998 09:48:56 -0400 From: bil kleb Subject: Re: COZY: Selvedge UND > Chris Byrne wrote (in html format?): > > I have just realised that I have cut the selvedge off the UND for my seat back. no big deal. > The plans state that the selvedge must be removed from the BID, > and that the UND should be butted selvedge to selvedge. They do not > say that you must not remove the selvedge from the UND. correct. > Have I committed a cardinal sin by removing the selvedge from the UND. no. > I have not yet done the layup so can easily cut some more, no need. > but it appears to me that I will be able to get the edges much > straighter with the selvedge no longer there. i don't understand why removing the selvage would allow you to get the edges straighter, but you will find that you wish you had left the selvage when you do the layup. elsewhere during construction you will have to deal with uni that doesn't have selvage edges and you will find that you have to deal with an unraveling mess unless you get clever about using masking tape. (see chap 10, page 5, step 4, paragraph 3 and the accompanying figure 32.) -- bil Date: Tue, 08 Sep 1998 16:02:40 +0200 From: Rego Burger Subject: COZY: Selvedge UND To answer Chris Byrne mmm.. another down under I presume? Well.... the MAIN reason for not cutting the selvedge is to stop the UND from fraying......you by now must have noticed that it just falls apart without one.....also it is easier to line up with it and keep things straight... In my opinion to your question if it is a sin = NO but just make sure that where you have made any butt "joints" of UND that it must be at least covered by either a BID layup or another UND crossing it or else it will simply crack...under pressure. UND is only strong down its length and not across it.(90:10) If you ever really need to join UND lengthwise (avoid it by cutting a longer piece ) make sure that you overlap by a min. of 1" in-line with the fibre (an extension). Note overlapping parrallel to the fibre is pointless as UND is only 10% stong across the fibre orientation.(it just makes a ridge, hence the practise to butt join it.) BID MUST be overlpped by 1" (min) if you do any patching....! This is to distribute any forces around this joint area...... ALways peelply any joints to get rid of sharp edges. Plan your cuts well and avoid joins... your craft will be lighter and stonger.... joining should only be for repairs! as a general rule. Hope this makes sense? Good Luck! Rego Burger Web site: http://home.intekom.com/glen/rnb.htm e-mail home- mailto:rnb@intekom.co.za RSA From: "L. Wayne Hicks" Subject: COZY: New BID Selvage Date: Tue, 8 Sep 1998 11:14:41 -0400 -----Original Message----- From: Tom Brusehaver [SMTP:tgb@cozy.netco.com] Sent: Tuesday, September 08, 1998 9:39 AM To: cozy_builders@canard.com Subject: Re: COZY: Selvedge UND Tom Wrote: BTW, the last roll of BID I got from Wicks had a different edge. No selvedg that I could detect. [L. Wayne Hicks] Yeah, I noticed this too. Instead of a selvage that's been "weaved", the selvage on my latest BID is a single strand sewn up the edge. This new selvage looks very non-intrusive and is inviting you to leave it there and not bother with removing it. I'm sure we'll get the full story sometimes soon from Nat, but I still cut off the selvage off when glassing my fuselage bottom this weekend. Wayne Hicks Cozy MkIV #678 Chapter 6 (soon to be finished!) Date: Thu, 10 Sep 1998 06:04:16 -0400 From: "Jeff S. Russell (http://www.AeroCad.com)" Subject: Re: COZY: Selvedge Chris Byrne wrote: > I have forgeten who it was, but one of you asked about the size > of the selvedge on my cloth. Wicks is selling BID that has a different selvedge that overlaps with out the air bubble problem. No need to trim it off. -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com P.O. Box 7307 Port St. Lucie FL. 34985 2954 Aviation Way Ft. Pierce, FL. 34946 Shop# 561-460-8020 7:00am to 3:30pm Home# 561-337-1579 Composite workshop info: http://www.Sportair.com Date: Thu, 10 Sep 1998 07:10:00 -0500 From: Alan Wirbisky Subject: COZY: Cozy : Seatback Issue I've "finished" my seatback bulkhead and am disturbed by the fact that the Bid layer peels from the micro on pieces that I have cut out and tested, while the UNI layer peels a nice layer of foam when stripped from the same sample pieces. My take is that I didn't get as good bonding between the BID and micro as is needed. Is that true ? If so, what could have been the cause ? If possible, is the part recoverable by stripping the glass, sanding the micro (and then what - micro or epoxy ?) A few facts : L335 Epoxy, Slow Hardener. UNI laid up "normally", i.e., foam surface micro'ed, dry cloth unrolled onto surface, epoxy stippled into glass. BID cloth wetted out on a piece of plastic sheet, then transferred to micro'ed foam. Not much more epoxy added, then stippled out. Thanks for your thoughts. I really would like to get off on the right foot with this project. Date: Sat, 12 Sep 1998 00:27:06 -0400 From: "Marc J. Zeitlin" Subject: Fwd: COZY: Cozy : Seatback Issue Alan Wirbisky wrote; >... My take is that I didn't get as good bonding between the >BID and micro as is needed. Is that true ? Sure sounds like it. >L335 Epoxy, Slow Hardener. UNI laid up "normally", i.e., foam surface >micro'ed, dry cloth unrolled onto surface, epoxy stippled into glass. BID >cloth wetted out on a piece of plastic sheet, then transferred to micro'ed >foam. Not much more epoxy added, then stippled out. I'm going to guess that what's happened is that the UNI had more epoxy in it, and is soaked through into the micro to form a good bond. However, although you may have wet the BID enough to get it fully wet out, there wasn't enough epoxy to fill the space between the BID and the micro, so you got a poor bond. I'd recommend using a squeegee rather than a stippler - I've had much better luck at avoiding air bubbles and ensuring wet-out that way. I also think you get a higher contact pressure with the squeegee, to ensure epoxy contact. To fix, you can certainly peel off the glass, sand the underlying cured micro, and then glass over it. When I glass over dry surfaces, I try to put a thin layer of epoxy on the surface BEFORE applying the glass (even if the glass is pre-wet on plastic sheet) to ensure a good epoxy connection. Hope this helps. S -- Marc J. Zeitlin                     marcz@ultranet.com 3 Sweetbriar Way                  http://www.ultranet.com/~marcz Acton, MA  01720                 http://cozy.canard.com/ Date: Sat, 12 Sep 1998 09:11:24 -0400 From: David Domeier Subject: Re: COZY: How Good is Good? Joe, I've been out in the world earning a living and haven't checked into the forum in over a week...had some 59 messages...so that's why this reply is so tardy. You're right, you are having beginning builders jitters. Don't sweat it, we all did. My comments - you'll do fine. Your concern convinces me the quality of your work is above average. Fiber orientation is important where the plan calls for UNI, i.e., wings, canard, fuselage. Does it have to be perfectly straight, hell no. Make it as straight as you can before the glue begins to cure. Leave enought time to do a good job of squeegy or too much glue will stay in the fibers causing more weight than necessary. The angle of UNI on the wing and carard should be reasonably close to plan orientation to provided for max strength. But that isn't difficult, I drew a line on the foam and orientated the glass to it. Where a 45° BID orientation is called for, a 42.5° lay up isn't going to cause the machine to come apart. Don't sweat it unless you are a perfectionist and want to spend 12 years building your airplane. dd LEZ and MKIV built and flying....neither has come apart inflight yet. Date: Tue, 08 Sep 1998 10:28:00 -0800 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: Selvedge UND Chris, I see no problem with cutting the selvedge edge off the UND, other than added difficulty in handling it and laying it into place. The whole point of the UND is to get all (or almost all) of the fibers going in one direction, namely lengthwise. As long as you accomlish this, the other perpendicular fibers are just there to help keep things tidy and aligned. Edge shouldn't matter. One suggestion on handling it into place might be to run a thin strip of tape along the edge before you attempt to lift it into place and wet it out. once it is in place and wet, you can trim off the taped edge before laying another piece in alongside it. On another note, pursuant to what Marc mentioned about turning off extraneous attatchments, I am leaving your full message unedited, just as it arrived at my mailer. I'm no expert, but this looks like an HTML attatchment. Perhaps you could turn it off in your mailer's "options" menu. If I ever send out something like this, I would appreciate being told, so I can fix it, so I hope you take this in the good spirit it is intended :-). --Howard Rogers >Maybe someone can answer this for me. > >Just reading the postings regarding the butting of edges when using UND and >I have just realised that I have cut the selvedge off the UND for my seat back. > >The plans state that the selvedge must be removed from the BID, and that >the UND should be butted selvedge to selvedge. They do not say that you >must not remove the selvedge from the UND. > >Have I committed a cardinal sin by removing the selvedge from the UND. >I have not yet done the layup so can easily cut some more, but it appears >to me that I will be able to get the edges much straighter with the >selvedge no longer there. > > >Thanks >Chris Byrne >Sydney From: "Nat Puffer" Subject: Re: COZY: Dusting Date: Mon, 21 Sep 1998 11:30:22 -0500 People, Dusting micro over a wet surface is not recommended. The microspheres will draw up epoxy and at the same time will not be completely coated. The Cozy Mark IV structure greatly exceeds the strength required for the "normal" category, but we do not want to see builders taking shortcuts which could compromise the safety factor. Nat ---------- > From: L. Wayne Hicks > To: 'cozy_builders@canard.com' > Subject: COZY: Dusting > Date: Monday, September 21, 1998 11:57 AM > > > Group: > > Any of you familiar with "dusting"? Supposedly, what you do is layup and > squeegee the part as usual, then sprinkle or "dust" the part with > microspheres. > > Paul K explained once that some Long EZ drivers were doing this to get a > jumpstart on filling and sanding. Supposedly, the micro will suck up some > of the excess resin and fill in the voids and valleys. I'd like to hear > more from builders who have tried this. Pros/Cons? Success/No Success? > > > __________________________________________ > L. Wayne Hicks SpaceTec, Inc. > Sr. Engineer 3221 North Armistead Ave > 757-865-0900 phone Hampton, VA 23666 > 757-865-8960 fax http://www.spacetec-inc.com > From: cdenk@ix.netcom.com Date: Mon, 21 Sep 1998 14:08:27 -0500 (CDT) Subject: Re: COZY: Dusting I would assume it possible for the dusting of micro to soak up epoxy, making the layup too dry, and not be able to see that. Date: Mon, 21 Sep 1998 15:34:35 -0400 From: Paul Krasa Subject: RE: COZY: Dusting I guess I aught to chime in on this. I "dust" the surface of my external layups with micro. The process is to pour micro over the wet surface and then to rub the micro in lightly with your hands. Advantage: Fills in the weave, is easier to sand and gives better adhesion. I typically start with 80 grit to sand this layer off, and then add the next layer of filler. Disadvantage: Dry micro gets on the floor, but once the sanding process starts, filler materials gets all over everything, so whats alittle more. The filling and sanding process is the most tedious, and nasty job in building this type aircraft. Everybody develops a technique of there own. For a better discussion of finishing go back a few years. Both Jeff Russel and others lent tips which really speed up the finishing process. Hint for filling pin holes: Mix silca flake (cabosil) with epoxy until it is the consistency of tooth paste. Squigee onto surface making sure there is no excess or Squigee lines left behind. Dust the surface asw described above. This will fill 90-95% of the pin holes. If you do not dust the surface, it is harder than pure epoxy and almost impossible to sand. Paul Krasa Long EZ 214LP p.s. Hey Wayne what does George say about "dusting?" At 13:44 9/21/98 -0400, Jim Hocut wrote: > >> >> Any of you familiar with "dusting"? Supposedly, what you do is >> layup and >> squeegee the part as usual, then sprinkle or "dust" the part with >> microspheres. >> > > > >I tried that once, wasn't happy at all with the results. Seemed to >me that it made extra work. I wound up with a mess. > >I've been trying a finishing method described in the Canard Pusher >where you > >i) Sand the glass dull (they suggest doing 10 strokes in one >direction w/ 36 grit, then 10 strokes in the other direction as a >starting point) > >ii) Wipe just a very thin film of epoxy on with a paper towel > >iii) Dry micro, let cure. > >iv) Sand with a sanding spline just until you get to the glass, if >any low spots remain repeat i, ii, iii for the low spots > >v) Use a soft squeegee with lots of force to apply pure epoxy (this >fills any pinholes etc.), remove any excess. Let cure till at the >gell stage, repeat 4 more times, then let fully cure and wet sand w/ >220 and your ready to paint. > >I've been trying this on my canard and it seems to work well. BTW, I >stumbled into a little trick that makes sanding easier. I applied >the dry micro as above (I was using EZ-Poxy), then carried the canard >out in the sun so the micro would hurry up and cure. The surface of >the micro turned a dark orange (probably some sort of oxidation >reaction which was helped along by UV), while micro just under the >surface remained light yellow. That made it really easy to see where >there were low spots while sanding. > >Jim Hocut >jhocut@mindspring.com From: SWrightFLY@aol.com Date: Mon, 21 Sep 1998 16:24:34 EDT Subject: Re: COZY: Dusting In a message dated 9/21/98 12:44:30 PM Central Daylight Time, jhocut@mindspring.com writes: << v) Use a soft squeegee with lots of force to apply pure epoxy (this fills any pinholes etc.), remove any excess. Let cure till at the gell stage, repeat 4 more times, then let fully cure and wet sand w/ 220 and your ready to paint. >> I have also been using this method in the finishing of my Stagger EZ after dusting the last layup with mico baloons. It is important to wait about 2 hours (at 70 degrees) before dusting to avoid wicking-up an excessive amount of epoxy from the last ply. I finished my Varieze using the "conventional" method back in 1980 and find the new method developed by Cory Bird at Scaled to be easier and quicker. I suggest using West system as it sands easier. Steve Wright Wright Aircraft Works Date: Mon, 21 Sep 1998 17:35:14 -0500 From: Bulent Aliev Subject: Re: COZY: Dusting I experimented on small layup with "dusting". It was messy and I can not see any benefit of using it.. Bulent Date: Tue, 22 Sep 1998 09:45:43 +0200 From: Rego Burger Subject: COZY: Dusting Methods and styles will vary as personalities, abilities etc.etc. I do agree with NAT and others that "dusting" micro onto a WET layup is WRONG! Micro acts like blotting paper sucking resin UP out of a wet layup. But with some of my many experiments have found using this technique for what I call "Weave Fill" on an already dried / completed surface does work with reasonable success. This way there is no way to deprive the STRUCTURE of much needed stiffening resin if it has cured. I did this on my strakes after cure to fill the WEAVE. I squegeed the raw resin over the surface and allowed it to settle, armed with gloves I lightly spread micro over to see the effect. I kept adding micro till it was as white as snow.... the result, a mirror smooth surface ready for primer. Take note... this just filled the depressions in the cured weaved surface, without the need to sand..sand...sand. You still need to fill deeper irregularities with dry micro but I sure saved lots of sanding time on surfaces that are reasonably smooth and straight already. What most folks do is lay dry micro about 1/8" thick over the entire surface and sand down to the skin. Inadvertantly some of the skin is sanded away. Unless you colour coded your layups you don't really know how much you have sanded through. Also it can only be done effectively on near horizontal surfaces, else the micro just lands on the floor. The spreading is done with a lightweight "squeegee" made from folded paper. No "force" just keep moving to and fro and let the resin soak up the micro. What ever you do, do NOT "Dust" a WET layup of structural importance....wings,canard,fuselage,winglets. ( about the whole 'plane ) Rego. From: cdenk@ix.netcom.com Date: Tue, 22 Sep 1998 05:43:24 -0500 (CDT) Subject: Re: COZY: Dusting Instead of dusting with dry micro, squeege on slurry or dry micro immediately after, or before knife cut time. Move the squeege in a direction to keep the fibers stretched straight, and always at the end of fibers in the direction to lay the fibers down. From: "Nat Puffer" Subject: Re: COZY: Dusting Date: Tue, 22 Sep 1998 08:38:23 -0500 Dear Dick, The purpose of peel ply is to hold the weave down (a poor man's vacuum bagging) so that it doesn't soak up an excess of epoxy, and expand like a sponge. Burt's objections were based on his belief that builders might use it to soak up too much epoxy from the layup. Used correctly, it produces a lighter and stronger layup than without. Regards, Nat ---------- > From: Cozy7971@aol.com > To: cozy_builders@canard.com > Subject: Re: COZY: Dusting > Date: Tuesday, September 22, 1998 9:42 AM > > In a message dated 98-09-22 07:41:06 EDT, BurgerR@telkom.co.za writes: > > << I do agree with NAT and others that "dusting" micro onto a WET layup is > WRONG! > Micro acts like blotting paper sucking resin UP out of a wet layup. >> > > While I don't intend to try dusting (it sounds messy and may have some adverse > affects) I would like to pose a question in the form of a few observations: > > 1. The main point against dusting seems to be that it will suck resin out of > the layup. > 2. A lot of people have used peel ply over large sections of the airframe to > draw resin out of the layup and produce a smooth surface. I believe Burt > Rutan recommended against this in an early CP as it would starve the layup. I > have a further memory that he changed his position on this later but I'm not > sure of that. Perhaps I shouldn't even mention it here as it could mislead > people. > 3. Vacumn bagging seems to be an accepted (recommended????) method method of > construction. In this case you peelply the layup, add a layer of absorbent > material followed by sealed plastic. Applying a vacumn will suck the access > resin out of layup and produce a very light part. > > So, why is the affect of dusting different from peel ply or vacumn bagging in > its ability to "starve a layup"? > > I'm not attacking the idea or rebuttal I've seen -- just asking why. I guess > one possible response is that all three alternatives are bad ideas for all or > part of a Cozy. > > Dick Finn > Cozy Mark IV #46 > Currently as much completed as possible in the basement. I'm finishing the > garage and will be back in production in about two months. > > Date: Tue, 22 Sep 1998 09:41:04 -0800 From: hrogers@slac.stanford.edu (Howard Rogers) Subject: Re: COZY: Dusting Dick Finn says: >While I don't intend to try dusting (it sounds messy and may have some adverse >affects) I would like to pose a question in the form of a few observations: > >1. The main point against dusting seems to be that it will suck resin out of >the layup. Dick, I'm not sure this is the reason for recommending against "dusting". Microspheres are, well, microscopic. They can move through the epoxy, and that includes moving in between fibers. The basic education portion of the plans cautions against using any micro between layers of a layup, because the fibers should be surrounded by PURE epoxy. This is in a perfect world, of course, and I have always tried to keep micro out of the layup. Some is bound to migrate up from the slurried foam, though, but I think this falls into the category of an unavoidable, undesirable side-effect. Why add even more opportunities for a poor quality resin/fiber bond by adding more microspheres on top of the layup? In my opinion, the same goal can be accomplished by bead-blasting the finished layup, and troweling in a mixture of epoxy and micro to fill the weave. No danger of starving or contaminating the glass/epoxy ratio. This is a bit more work than dusting, I suppose, but it might not be, if the micro mixture troweled in uses West Systems epoxy, which is very easy to sand. And sand you must, because no techinque I have heard of will eliminate that step, anyway! >2. A lot of people have used peel ply over large sections of the airframe to >draw resin out of the layup and produce a smooth surface. I believe Burt >Rutan recommended against this in an early CP as it would starve the layup. I >have a further memory that he changed his position on this later but I'm not >sure of that. Perhaps I shouldn't even mention it here as it could mislead >people. I'm not aware that Burt ever changed this reccommendation. The reason for it, though was just the opposite. In order to "flatten out" the surface, peel ply ADDS additional epoxy, effectively filling the valleys in the weave. Excessive use of this technique will add weight to the part. >3. Vacumn bagging seems to be an accepted (recommended????) method method of >construction. In this case you peelply the layup, add a layer of absorbent >material followed by sealed plastic. Applying a vacumn will suck the access >resin out of layup and produce a very light part. Ture enough. The key here is the compression of the matrix, provided by the vacuum bag. This more than offsets the "valley-filling" of the peel ply. Nothing wrong with it, if it is done correctly. Biggest problem is that it adds considerable complexity (read: time) to the building process. Matter of skill and choice. > >So, why is the affect of dusting different from peel ply or vacumn bagging in >its ability to "starve a layup"? I hope the above answers these questions. regards, -Howard Rogers Date: Wed, 23 Sep 1998 10:08:50 +0200 From: Rego Burger Subject: COZY: Dusting snip<<<<<>>>>>"I'm not sure this is the reason for recommending against "dusting". A layup is made up of resin and cloth composite. ( let's leave foam out now for a while ) The Ideal MINIMUM ratio is 50:50 resin to cloth by weight. As I said some time before this can only be tested from samples of completed work. What the guys did in the lab. for me when I had some samples tested here in the early days is to "burn" the samples after weighing it first.... then after burning it they weigh the left-over ash... this "ash" represents the glass content. What burnt "away" was the resin. Now if you add micro to a WET layup it WILL absorb resin from the laminate if it has NOT cured. The problem is the sooner you "DUST" the more it will absorb. The more micro "DUST" you add the more it will absorb. The estimated amount is 10% in weight. So we now can have a situation of having a 40:60 R/C (resin to cloth ratio) or even worse. Ah! you may say my plane will be lighter! Yes... but weaker... WHY? Well the resin functions as a bonding agent and stiffening agent, two valuable properties, reduce their importance by 10% and we're bordering on trouble. The worst part is the control....we just don't know how much is too much until too late. Rather spend time on working out the volume of resin needed per layer per sq. Yard and you wont ever be too heavy without the correct strength. When you add peel ply the same applies... don't place it over a "dry" layup and force the resin from the layup into the peelply... after gentle squegeing the surface to identify wet spots ( colour change on p/p) add some resin in the "dry" areas of the p/p to prevent them from being absorbed by the p/p while you sleep. PRACTISE....Practise till you know how much to add when. Rego. From: "Nat Puffer" Subject: Re: COZY: Dusting Date: Thu, 24 Sep 1998 07:44:39 -0500 Jim, I believe that the 40:60 ratio gives the maximum strength in pressure molding, where there would be no voids. In the wet layups like we do, there would be voids at 40:60. Voids are most serious where the layup is under compression, like landing gear struts, top of wings, etc. In compression, layups can buckle more easily than in tension. For wet layups like we are using, 50:50 is a better resin to glass ratio. Nat ---------- > From: Jim Hocut > To: 'Rego Burger' ; cozy_builders@canard.com; hrogers@slac.stanford.edu > Subject: RE: COZY: Dusting > Date: Thursday, September 24, 1998 9:22 AM > > On Wednesday, September 23, 1998 4:09 AM, Rego Burger > [SMTP:BurgerR@telkom.co.za] wrote: > > > A layup is made up of resin and cloth composite. ( let's leave foam > > out > > now for a while ) > > > > The Ideal MINIMUM ratio is 50:50 resin to cloth by weight. > > > In forums at OSH and S&F Burt Rutan, Andy Marshall, Martin Holliman, > Gordon Bowen and others have all said that the ideal resin:glass > weight ratio is about 40:60 (one said it was 38:62, but that's > picking nits). I've never done tests to confirm what these "experts" > have said, but I do know that if I pre-weigh an exact amount of resin > and glass (i.e. 50:50) it gets pretty darned wet and that plenty of > resin can get squeegeed out and still have no dry spots. > > > > Jim Hocut > jhocut@mindspring.com > > > Date: Thu, 24 Sep 1998 08:50:43 -0700 From: "LCDR James D. Newman" Subject: COZY: Re: LG Local Layup Error! Is mechanical bond good enough? Hi Dave, Jody and All, > re "I peel-plied the overall lay ups. Is the mechanical bond of local lay ups over the cured but peel-plied overall lay ups of sufficient strength to continue or ...?" > Yes. In fact the winglet is attached to the wing over a peel-plied surface since day one in this process. I think I mentioned this before, but during the Voyager project, they learned that even though they peel-plied everything, sanding it with 80 grit before the next ply made for an even stronger mechanical bond. Infinity's Forever, JD From: Epplin John A Subject: COZY: Micro and Peel ply Date: Wed, 23 Sep 1998 08:10:34 -0500 Just thought I would add my .002 cents worth. When I made the speed brake door, I carefully weighed all the components that went onto the inside lay-up. This was a fairly simple part which one could trim the cloth to very near size for min scrap. When I applied the peel ply, I weighed the material itself, squeegeed it into place, ended up with some dry spots, applied epoxy to these and recorded all weights. I believe the actual figures may still be around somewhere, not sure. When I removed the peel ply, it weighed more than the combined dacron and epoxy added to wet it out. Obviously the process removed epoxy from the part. The amount of epoxy removed amounted to about one percent of the total epoxy used in the lay-up. I weighed the scrap that was knife trimmed also. I did not burn the resin from the scrap. There was very little resin, only a bit on the edge. I did make an estimate of the resin left in the scrap, don't remember the exact number, was rather small percentage though. The overall resin to glass ratio was about 48 epoxy to 52 glass. This was within no more than 2 percent error, at least I convinced myself of that at the time. I did not include the micro mixture in the resin to glass ratio. Obviously some of this ends up in the cloth. End result: The peel ply process removes some weight from the system, although very little. When finishing, assuming the contour is correct, no filler will be required on the peel plied surfaces. This should be an additional weight saving. Another related observation. When applying micro to some of the larger cell foam, I tried to mix it a little thicker than for the smaller cell foams. Even doing this, I noticed a bit bleeding through the first layer of cloth. I had squeegeed the surface as dry as I could get it. Maybe letting the mixture start to gel would be better? This may not be easy to control for large areas. I always completed the lay-up as rapidly as possible once started, trying to get the next layer on before the gel started. For large surfaces such as the wings, when I applied the peel ply, the surface was starting to gel in spots. I have a real mix of epoxy in this project, started with 2427 for the tub and canard, center spar, gear lay-ups etc. Then when it became unavailable went to Aeropoxy which I used for the wings, much of the interior parts, seats, armrests etc. Finally finishing the strakes now using MGS 235. I really don't know what I am trying to say here except there are things that are less than ideal that are going to happen. Try to minimize the effect the best we know how. I know if a significant amount of micro drifts into the laminate it has to affect the peel strength of the part. I must assume this has been taken into account in the design. Keep building, don't sniff too much epoxy! John Epplin Mk4 #467 From: lschuler@cellular.uscc.com Date: Fri, 25 Sep 98 10:23:07 -0600 Subject: Re[2]: COZY: Dusting Dick Finn wrote: >1. The main point against dusting seems to be that it will suck resin out of >the layup. FWW, here's my take on this issue: I don't think it's being portrayed accurately. I don't believe it's the "sucking out" of resin as much as it is that the micro will actually settle in a 'wet' resin between the glass strands which would, in fact, weaken the cured epoxy/glass matrix. Even more so if the micro were rubbed or pressed into the weave, so to speak, while the structural epoxy/glass is still uncured. Should be well known and is stated in the plans and elsewhere explicitly that micro is NOT a structural material. Entraining micro between the glass strands should be a definite NO-NO except in a few very specific, localized applications. >.... >So, why is the affect of dusting different from peel ply or vacuum bagging in >its ability to "starve a layup"? Another FWW and my take: I use peel ply on just about everything, so far. I also vac bag some parts. My opinion is that the peel plied parts, if not vacuum bagged, may be very slightly heavier than if I didn't use peel ply, but not sure. The peel ply does seem to help keep the glass from expanding and floating on a layer of excess epoxy underneath though. I haven't done any weight comparisons. I am basically filling the weave with pure epoxy via the peel ply during layup rather than waiting till cure, then filling with dry micro. 'If' the peel ply is laid on as if it were another layer of glass (which is the right way to do it, I think), the valleys between the glass bundles (weave) actually get filled in with epoxy. Now it is true, that I don't automatically add epoxy to my layups after laying down the peel ply; I generally squeegee the peel ply first which removes "excess" epoxy and does pull this to the surface of the peel ply and gets spread around. That's a good thing; this epoxy is obviously "excess" to the needs of the layup. I do not use any more force etc than is normally used for the glass. I then look for lean areas and add epoxy as needed; easy to see with the peel ply. Nice thing about this is that my layups are then fairly even in epoxy content over the entire area and the weave is filled, leaving near perfect surface for finishing. To make a poor man's vacuum bag: do layup as usual, then peel ply, then lay down some 1-mil clear plastic. Squeegee the plastic very hard and move all excess epoxy to the edges of the plastic. This is easier with a bit of epoxy on the surface of the plastic to keep the squeegee from pulling the plastic. If it's a bulkhead, cover with another 1-mil sheet and lay a sheet of masonite on it with some weight to keep the panel flat during sure. Weight doesn't need to be much; a brick or two is plenty. After cure, you will find that there are a number of ridges in the plastic and it will look terrible. These ridges are full of "excess" epoxy and lay between the peel ply and plastic. When removing the peel ply, these epoxy ridges tend to tear the peel ply, so be careful about removing the peel ply. About as simple as it gets. Vac bagging seems to be useful in getting even more "excess" resin out and providing the lightest 'practical' part. It's a real pain in the toosh relative to just doing peel ply. Lots of extra time in preplanning stage. Actual bagging is fairly easy, but I've had some difficulty getting the vac pulled before the epoxy starts to kick. If I were using some of the longer pot-life epoxy it would be better, but I'd rather use the regular stuff for regular layups. In a one-off project such as we do, simplicity is the name of the game. One epoxy, one mix ratio, one pot life etc keeps it simple. As for dusting: I haven't tried this yet, 'BUT' if (repeat "IF") dusting is done with the same principal, intent and general method as our normal contouring/fill, then it may make some sense. This would strictly be after the structure has cured for the reason stated above. Painting or rubbing epoxy on a cured and sanded layup, then dusting and rubbing micro into the tiny depressions between the glass bundles in the weave and in pinholes may be easier than trying to press dry micro into them (which is the method called out in the plans). In any case, there will likely be a need for some dry micro fill for heavier contouring which a 'dusting' would not do. Dusting could maybe even result in some weight savings (small) and be easier to sand since a higher micro/epoxy ratio might be achievable. My take (FWW) is: 1. As with any fill/contouring, I would NOT even consider dusting until the "structure" has "completely" cured. 2. I may consider dusting as an easy and good method for weave fill and very slight contouring ONLY. 3. Dry micro or epoxy/plastic balloons will still probably be necessary and easier for 'contouring' some larger/deeper areas. Larry Schuler MK-IV Plans #500 Date: Tue, 31 Mar 1998 00:47:35 -0500 From: "Hunter GA (Gary) at MSXSCC" Subject: [canard-aviators] RE: High temp resin [The Canard Aviators's Mailing list] John writes; > My real question is what fibers and resin/hardner would be best > for me to use under the cowling. I want to make a couple of layups for > the cooling air plentum and intake air plentum. These two parts are > going to be very close to very hot surfaces-- > John, The best thing I can suggest for "under the hood" applications is EPON Resin 828 from Shell and DCH from DuPont. (DCH stands for Diaminocyclohexane) This system will produce an Tg of about 350F or and HDT of about 300-310F. If you remember my post cure rule of thumb - post cure it at or above the expected Tg value for 2 hrs. min. The is system is an exception to the rule. It can be post cured as low at 200F and still obtain a Tg of 350F. This is the system I used to build the Kevlar plenum covers on "Pushy Galore". Another option is Isopheronediamine or IPDA. Same kind of performance, but it requires the normal post cure schedules. The mix ratio of DCH to EPON 828 by weight is 16 parts by wt. DCH to 100 parts by wt. EPON 828. The mix ratio of IPDA to EPON 828 by weight is 28 parts by wt. IPDA to 100 parst by wt. EPON 828 Sources EPON Resin 828 - available in quarts - ask for DCH or IPDA too. They might have it. E.V. Roberts, Inc. (authorized Shell Distributor) Culver City , CA 800-374-3872 DCH DuPont 800-231-0998 - ask for distributors of small quantities to purchase first - if they don't have any then you can ask for a small sample. IPDA Huls America 800-631-5275 - same deal - ask for vendor first - then a sample. DuPont and Huls are major manufacturers and don't sell small quantities. I do not know of any distributors for their products. You will have to ask them. If they don't have any, then you can ask for a small sample. These curing agents are corrosives (as is most curing agents) and give off a powerful ammonia smell and sometimes make visible fumes in the air. They are not any more toxic than any other curing agent when handled properly. They just look and smell that way. Sincerely yours, GARY A. HUNTER - VARI-EZE - N235GH - EAA Technical Counselor Technical Service Representative Epoxy Resins & Curing Agents Shell Chemicals, USA Toll Free in North America - 800-832-3766 International - 713-246-8295 Facsimile - 713-241-1606 E-Mail - gahunter@shellus.com ---------------------------------------------------------------------- (c) 1997 Canard Aviators. This information is provided solely and exclusively for the personal use of Canard aircraft builders and Pilots and may not be used, copied, quoted or referenced in any other publication or medium without the express written consent of Canard Aviators support@canard.com. Date: Mon, 28 Sep 1998 16:53:24 -0500 Subject: Re: Re[2]: COZY: Dusting From: mikefly@juno.com (Michael B Bowden) I have not "dusted any structural parts. However I have dusted a few small parts that are covers or hatches inside the EZ . Post cured by setting part under the hatch of my wife's car on a sunny day. (She doesn't mind the smell) I was able to sand, prime and paint the next day. Mike Bowden ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] From: lschuler@cellular.uscc.com Date: Thu, 17 Dec 1998 15:49:43 -0600 Subject: COZY: Air pockets and flaws in heavy layups I'd appreciate some suggestions if anyone has had experience on this. Is there any reasonable way to find air pockets, voids or other flaws inside heavy glass layups such as a nose strut or main gear hoop? By resonable, I guess I mean something us garage-level airplane manufacturers can do without morgtaging the house to pay for lab testing? Larry Schuler Cozy-IV plans #500 From: lschuler@cellular.uscc.com Date: Fri, 18 Dec 1998 10:33:20 -0600 Subject: Re[2]: COZY: Air pockets and flaws in heavy layups Rego wrote: >SNIP >The pressure gets rid of 99% of the voids which we can't achieve with >hand layups. We're talking about microscopic things here that even >electron microscopes are expected to pick up. >SNIP JUST TO HELP DEFINE MY QUSETION A BIT MORE: THE SURFACE VOIDS I HAD IN MY NOSE STRUT WERE NOT MICROSCOPIC OR EVEN AS SMALL AS THE ONES WE WORK HARD TO GET OUT IN OUR OWN HAND LAYUPS. THESE WERE ABOUT THE WIDTH OF A PENCILE, ALMOST AS DEEP, AND OVER AN INCH LONG!!! THE KIND OF VOID, IF IN THE MIDDLE OF THE ASSEMBLY, WOULD MOST DEFINITLY CAUSE TROUBLE AT SOME POINT. IN MY CASE, IT WAS OBVIOUS THAT THE PRESSURE PROCESS IS NOT WHOLLY PERFECT AT GETTING AIR OUT. MAYBE THE AIR IS PRESSED TO THE SURFACE...WHICH CREATED THE VOIDS I HAD. I DO NOT KNOW THE EXACT PROCESS/OR PROCEDURE OF THE LAYUP, EPOXY, PRESSURE APPLICACION OF THESE THINGS ANY MORE THAN I AM FAMILIAR WITH THE MANUFACTURE OF AN HARDWARE. THEREFORE, HAVING FOUND VOIDS AT THE SURFACE HAS LED ME TO THINK THERE IS A POSSIBILITY OF INTERNAL VOIDS. THOSE ARE THE ONES I'D LIKE TO BE ABLE TO SPOT WITHOUT SPENDING A FORTUNE IN TESTING. MAYBE ITS THE SAME AS TRYING TO FIND FLAWS IN THE INTERNAL STRUCTURE OF A BOLT. WHICH, FOR ME (I'M NOT A MILLIONAIR) MEANS IT AIN'T GONNA HAPPEN. IF THAT'S THE CASE, SO BE IT. WHEN I SPOT A BOLT I'D RATHER NOT USE (BENT OR WHATEVER) I TOSS IT IN A BUCKET FOR USE ON THE LAWNMOWER OR SOMETHING. JUST A QUESTION OF HOW TO MAKE A SIMILAR SELECION OF PARTS WHICH ARE MADE OF HEAVY GLASS. JUST SEEMES TO ME THAT SINCE GLASS IS SOMEWHAT MORE TRANSPARENT THAN STEEL, THERE MAY BE AN EASY WAY TO SPOT INTERNAL FLAWS, OR DETERMINE WHEN A SURFACE VOID WOULD RENDER THE PART UNUSABLE. I HAVEN'T FIGURED THIS OUT YET; MAYBE SOMEONE ELSE HAS. Larry Date: Fri, 18 Dec 1998 12:27:19 -0800 Subject: Re: COZY: Air pockets and flaws in heavy layups From: alwick@juno.com (ok How) On Fri, 18 Dec 1998 10:33:20 -0600 lschuler@cellular.uscc.com writes: >THE KIND OF VOID, IF IN THE MIDDLE OF THE ASSEMBLY, WOULD MOST DEFINITLY >CAUSE TROUBLE AT SOME POINT. Actually, there is a real simple, fast way to determine if a layup like the gear legs has entrapped air. I thoroughly researched it a few years ago using statistically designed experiments. You just need to measure the specific gravity of the gear legs. This is accomplished by comparing the weight of the part while hanging in the air vs. when immersed in water. The ratio is the specific gravity. Basically, trapped air has quite an effect on the weight of the part when immersed. For my purposes, I needed to amplify the voids so while curing I placed the sample in a slight vacuum. This just increases the size of the void by reducing the pressure about it during cure. I didn't do my experimenting with fiberglass. Would be good for manufacturer to verify the sensitivity, then incorporate in his process to prove he has the process optimized. Then just check an occasional part. We found specific gravity measure was one of the keys to process improvement. Basically, if you don't have a way to measure the process output, it will eventually degrade. FWIW -al wick 87% comp. Cozy MkIV sn 389 with stock Subaru 2.5 engine. Computerized cockpit. Done building components. Expect completion date 6-21-99. ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866] From: NICEEZ@aol.com Date: Fri, 18 Dec 1998 21:54:57 EST Subject: COZY: Re: [canard-aviators] Air pockets and flaws in heavy layups In a message dated 12/18/98 4:45:47 PM Pacific Standard Time, lschuler@cellular.uscc.com writes: << I guess I mean something us garage-level airplane manufacturers can do without mortgaging the house to pay for lab testing? Larry Schuler Cozy-IV plans #500 >> Yes, you can weigh the finished part. You know what the glass cloth weighs and should know how much resin it takes to wet out a certain number of ply per square inch. If not conduct your own tests until you do. This has work for many high tech guys for years. As a matter of fact it is how I determine what a part should weigh while it is still on the drawing board. Have fun and Fly Safe Merry Christmas to All, Dale Martin Date: Sat, 19 Dec 1998 15:06:52 -0500 From: Dave Black Subject: COZY: Re: [canard-aviators] Air pockets and flaws in heavy layups Larry, > Is there any reasonable way to find air pockets, voids or other flaws > inside heavy glass layups such as a nose strut or main gear hoop? Have you tried the TAP TEST? Using a small object (the edge of a quarter will do), tap along the surface you wish to check. The sound will be unmistakably different when you encounter a void under the surface. You can trace out the shape of the void extremely accurately by using this technique. Best, Dave Black Velocity RG