From: "James E. Marker" Subject: COZY: Q: Peel-Ply, Wax Paper and Weight? Date: Sun, 19 Jan 1997 20:38:44 -0500 In chapter 4 it says to peel ply, wax paper and weigh down F-22 and F-28 (for example) for a flat cure. Do I have to use peel ply if I don't care about the finish? Could I just use saran wrap (which I have miles of - I know someone in a deli)? I will use peel ply where it will show (on the insrument panel for example). ============================================================================ ================= Jim Marker Email: jemstone@csra.net Web: http://www.csra.net/jemstone/ Cozy Mark IV #0581 Cozy Web Page: http://www.csra.net/jemstone/cozy.htm From: Lee Devlin Subject: Re: COZY: Q: Peel-Ply, Wax Paper and Weight? Date: Sun, 19 Jan 1997 22:02:47 MST > > In chapter 4 it says to peel ply, wax paper and weigh down F-22 and F-28 > (for example) for a flat cure. Do I have to use peel ply if I don't care > about the finish? Could I just use saran wrap (which I have miles of - I > know someone in a deli)? I will use peel ply where it will show (on the > insrument panel for example). > You _could_ use just saran wrap, but peel ply will make the surface better for bonding the next layups, and you will need to bond other surfaces to these parts. As for saran wrap, I much prefer 3 or 4 mil poly sheeting sold in hardware stores as drop cloths and dust barriers. It's typically found in 10x20' sections and doesn't have the tendency to crinkle and cling to itself up like .5 mil saran wrap. Lee Devlin by SERV05.SLAC.STANFORD.EDU (PMDF V5.1-4 #16063) with SMTP id <01IEI9GY6X2Q001VDM@SERV05.SLAC.STANFORD.EDU> for cozy_builders@hpwarhw.an.hp.com; Wed, 22 Jan 1997 08:23:13 PST Date: Wed, 22 Jan 1997 08:22:54 -0800 From: hrogers@SLAC.Stanford.EDU (Howard Rogers) Subject: Re: COZY: Q: Peel-Ply, Wax Paper and Weight? >> >> In chapter 4 it says to peel ply, wax paper and weigh down F-22 and F-28 >> (for example) for a flat cure. Do I have to use peel ply if I don't care >> about the finish? Could I just use saran wrap (which I have miles of - I >> know someone in a deli)? I will use peel ply where it will show (on the >> insrument panel for example). >> > >You _could_ use just saran wrap, but peel ply will make the surface >better for bonding the next layups, and you will need to bond other >surfaces to these parts. As for saran wrap, I much prefer 3 or 4 mil >poly sheeting sold in hardware stores as drop cloths and dust barriers. >It's typically found in 10x20' sections and doesn't have the tendency to >crinkle and cling to itself up like .5 mil saran wrap. > >Lee Devlin I would like to add my 2 cents worth, because this brings up a little tip that someone showed me, a long time ago, when I was building flat bulkheads and such. This works ALMOST as well as vacuum bagging, but only works on these types of parts--that you can lay up flat on your work table. I agree that the poly sheet is easier to work with than saran, but for these flat pieces, the saran is managable, so by all means-- use it up. I also agree, about the peel ply. Almost every time I have left it off in a circumstance like this, I ended up wishing I had used it, later. When in doubt: PEEL PLY! But whether you do or not, the following will work just fine: Wet out the layup as you normally would. Apply your plastic sheet to the surface. Borrow your signifigant other's pie crust rolling pin from the kitchen. Roll out the layup, squeezing excess epoxy out over the edges (you DID remember to cover the table with some plastic first, didn't you?) The plastic sheet prevents air from being drawn into the layup, after rolling. I make the part a little oversize, and trim to the line, after cure, with a fine tooth bandsaw blade. Oh yes. One final step: in the interest of domestic tranquility, go to the store and buy your signifigant other a new rolling pin, because you are going to want to keep the one with flakes of epoxy on the handles out in the shop, from now on (a much better place for it than imbedded in your skull!). Howard Rogers, A&P 2005148 Date: Tue, 18 Feb 1997 18:17:41 +0200 From: edegov@aztec.co.za (ernie de goveia) Subject: COZY: Strength of UND Hi all I have been building my cozy 3 from an UND material produced by Brouchier, France, with very similar specs to RA7715.The problem is that this UND is no longer available here at the southern end of Africa.What I can get is an aircraft approved 92145 UND of 6.49 ozs/sq yard. A composite designer here, says, using it as a covering for the wings is no problem, because, the heavier material was chosen for its handling properties, ie knock resistance, etc. As long as it is laid up at 45 degrees it will transfer all torsional loads to the the spar. The spar alone handles all bending loads. However, one has to be more carefull with the spar web as this material would be too light for this application. It would be O.K. though, to use an extra ply in the spar web. So, folks , what do you think? Does this sound good? or should I be thinking of importing UND from France or the States? Looking forward to your comments Ernie & Cosy3 in Cape Town From: Marc J. Zeitlin Subject: COZY: Strength of UND (fwd) Date: Tue, 18 Feb 97 12:17:10 EST Ernie de Goveia wrote; >......... What I can get is an >aircraft approved 92145 UND of 6.49 ozs/sq yard. How does that compare to the standard RA7715 weight for the major direction tows? If the cross tows are a substantial %age of the weight, you might be substantially weaker. >A composite designer here, says, using it as a covering for the wings is no >problem, because, the heavier material was chosen for its handling >properties, ie knock resistance, etc. As long as it is laid up at 45 >degrees it will transfer all torsional loads to the the spar. The spar >alone handles all bending loads. While these statements are somewhat correct, first of all the skins aren't laid up at 45 degrees - they're somewhere between 30 and 45. Also, changing the skin _MAY_ change the flutter properties of the structure - I would be _very_ reticent to change any structural layups. >However, one has to be more carefull with the spar web as this material >would be too light for this application. It would be O.K. though, to use an >extra ply in the spar web. I'd be loathe to make assumptions like that. You want a certain thickness of glass in each orientation - you'd need to calculate the exact amount of glass in each orientation and keep it the same, or slightly more. >.......... or should I be >thinking of importing UND from France or the States? Import RA7715 for the structural layups (get all you'll need for the rest of the project to save on shipping and customs charges). Use the other stuff for non-structural layups. Making changes to structural properties should only be done after extensive analysis and/or testing. The feedback of one designer saying "sure, that ought to work" isn't sufficient, and I say that as a M.E. -- Marc J. Zeitlin Email: marcz@an.hp.com by SERV05.SLAC.STANFORD.EDU (PMDF V5.1-4 #16063) with SMTP id <01IFLDD76IXY003GM5@SERV05.SLAC.STANFORD.EDU> for cozy_builders@hpwarhw.an.hp.com; Wed, 19 Feb 1997 08:15:37 PST Date: Wed, 19 Feb 1997 08:16:15 -0800 From: hrogers@SLAC.Stanford.EDU (Howard Rogers) Subject: Re: COZY: Glass comparison >Hi all, > >Glad we're discussing the glass comparison issue - since I'm substituting >myself. > >Think (me) that if the fibre is the same / the bundle of fibresand their >strand # per bundle is the same/ their direction is the same and the % of >fibres running per direction is the same ... then surely this is a >comparable fabric ....would even say that its the same.... > >The only difference on my own material (other than Ernie in Capetown) >compared to the Rutan UNI is the % Rutan = 95%/%5 across and mine is >93%/7% across and my material weighs 7% lighter - my resoning now is to >add an additional layer whenever needed to get to the same theoretical >gross weight (and i'm always over) plus a little bit to compensate for >the 93%/7% (2% short lenghtwise) - so my Cozy may not turn out the >lightest..... > > >Any comments? (please :-)) > >good building. > >chris #219 faffing in 08 Chris, My comment is this: I lose sleep when I hear things like this. There is more to glass cloth than the fiber count and orientation. There is also the surface treatment, and perhaps other unknown qualities. The main point here, is that the "guesstimate" method of building will yield a big unknown. Rutan did extensive testing on his design, at many stages throught the process, as well as tests of the finished product. He gathered enormous amounts of data before finalizing the design. Perhaps you are building something completely sound, and perhaps not. Perhaps it is unnecessarily overweight. The point is: who knows? Is Rutan approved glass cloth so expensive or difficult to get there that you are compelled to substitute? I can't imagine that it is such a signifigant percentage of the total cost of your airplane to consider this sort of "inventiveness". What is your peace of mind (and the lightness of your airplane) worth? --Howard Rogers A&P 2005148 Date: Wed, 19 Feb 1997 10:16:04 -0700 (MST) From: Ron Lee Subject: Re: COZY: Glass comparison At 08:16 97/2/19 -0800, you wrote: >>Hi all, >> >>Glad we're discussing the glass comparison issue - since I'm substituting >>myself. >> >>Think (me) that if the fibre is the same / the bundle of fibresand their >>strand # per bundle is the same/ their direction is the same and the % of >>fibres running per direction is the same ... then surely this is a >>comparable fabric ....would even say that its the same.... >> >>The only difference on my own material (other than Ernie in Capetown) >>compared to the Rutan UNI is the % Rutan = 95%/%5 across and mine is >>93%/7% across and my material weighs 7% lighter - my resoning now is to >>add an additional layer whenever needed to get to the same theoretical >>gross weight (and i'm always over) plus a little bit to compensate for >>the 93%/7% (2% short lenghtwise) - so my Cozy may not turn out the >>lightest..... >> > When I cut my canard cores, the foam was turned over between cuts. Since the cutting surface was not level, I ended up with cores that were too shallow in the middle. My solution was to add UNI glass to fill the depressions. NOW I have decided that solution MAY cause unpredictable consequences to in-flights forces. I am REBUILDING the canard rather than risk structural failure, however remote a possibility. Ron Lee Date: Wed, 19 Feb 1997 13:42:33 -0800 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: Glass comparison Hi all, Glad we're discussing the glass comparison issue - since I'm substituting myself. Think (me) that if the fibre is the same / the bundle of fibresand their strand # per bundle is the same/ their direction is the same and the % of fibres running per direction is the same ... then surely this is a comparable fabric ....would even say that its the same.... The only difference on my own material (other than Ernie in Capetown) compared to the Rutan UNI is the % Rutan = 95%/%5 across and mine is 93%/7% across and my material weighs 7% lighter - my resoning now is to add an additional layer whenever needed to get to the same theoretical gross weight (and i'm always over) plus a little bit to compensate for the 93%/7% (2% short lenghtwise) - so my Cozy may not turn out the lightest..... Any comments? (please :-)) good building. chris #219 faffing in 08 Date: Thu, 24 Apr 1997 19:08:32 -0400 From: INFINITY Aerospace Subject: COZY: Pre-made BID Tapes Hi Al and All, >Incidently, I'm planning on increasing the amount of surface area where the top skin of tank mates with strake ribs. I'll do this by gluing a narrow strip of foam to top side of ribs. This should greatly reduce chance of fuel leak, and have near zero weight penalty.< I use an 18" wide x 74" long piece of aluminum foil laid out on my table at a 45 degree angle to the edge of the table, and divide and mark it up with a permanent marking pen into 2" wide strips to make BID tapes on. Then I pull a ply of BID off a roll on my fiberglass stand across the marked up foil with the selvage parallel to the table. I pull enough across so I can fold it back onto itself after putting resin on the first ply and the foil, which will also alternate the BID plys. I then cut the 2 plys of BID AND the aluminum foil all at once down the 2" wide lines, getting about 53" long BID tapes. The aluminum foil keeps the wet BID tapes from skewing all over the place making a weaker BID tape job. I then lay the BID tapes on the foil in place and squeegee on the foil removing excess resin. Then remove the foil and squeegee any more excess resin out, then peel ply the tape job. Many already know this process. Now for the reason of this post. I went to Home Depot and picked up 2 - 1" x 1" x 6' aluminum angles. Covered both with mold release, put my pre-laid up wet BID tapes with foil on the outside of the angle, sandwich the other angle over the first angle and BID tapes with foil, set the sandwiched wet BID tapes out on the black top in the sun with a few weights, and in a few hours I have pre-made dried BID tapes that can be cut with scissors and used anytime later. The purpose is to have BID tapes in closed off areas that one can't usually put BID tapes and wish they could - such as the strakes in a mold less constructed aircraft. One can then take these pre-made cured BID tapes and flox them into place, say the fuel baffles in the top side of the tank, to increase the amount of surface area for the top strake tank skins to mate to, like Al wants to do. Only straight sections can be used. Around the leading edge, short straight sections can be used, or one side of the pre-made cured BID tapes could be scarfed many times to have a continuous curve. If someone was real rambunctious, a mold of the inside curvature of the strake fuel tank could be made to make one continuous curve of pre-made cured BID tapes. In fact, someone could sell these (Jeff ?). Any excess wet foil backed BID tapes I have, I roll them backwards into themselves against the foil, put them in a plastic cup and put them in the freezer - they'll keep for a couple days for use later if the resin is real fresh. If not, throw them out - you were going to anyway. HTH. Infinity's Forever, JD Date: Mon, 19 May 1997 21:37:28 -0400 (EDT) From: whittaker@mindspring.com (Glen E Whittaker) Subject: COZY: Cozy: Misc Questions 1. Chapter 3, Page 3 says: "With BID the selvage is always removed". What happens if this edge is not removed? 2. Does it matter if slurry is cured or un-cured before performing a glass lay-up over foam? 3. Can a scroll saw be used as a substitute for a band saw? Thanks! Glen Date: Mon, 19 May 1997 20:59:33 -0600 (MDT) From: Ron Lee Subject: Re: COZY: Cozy: Misc Questions At 21:37 97/5/19 -0400, you wrote: > >1. Chapter 3, Page 3 says: "With BID the selvage is always removed". What >happens if this edge is not removed? Will let someone else answer this one. > >2. Does it matter if slurry is cured or un-cured before performing a glass >lay-up over foam? Slurry the foam then add glass. Do not let it cure unless you peel ply it or sand after cure. Either of these two options seems less than desirable. > >3. Can a scroll saw be used as a substitute for a band saw? > That is all I had. Wish I had a band saw for a few things but I make do. Ron Lee >Thanks! > >Glen > > > Date: Mon, 19 May 1997 21:05:45 -0700 From: Richard Riley Subject: Re: COZY: Cozy: Misc Questions At 08:59 PM 5/19/97 -0600, you wrote: >At 21:37 97/5/19 -0400, you wrote: >> >>1. Chapter 3, Page 3 says: "With BID the selvage is always removed". What >>happens if this edge is not removed? > >Will let someone else answer this one. At the selvage the cloth is twice as thick as it is elsewhere. If we're talking about the top ply it's not that bad, but if you lay up over selvage you're guarenteed a bubble just "outside" of the selvage. -- Richard Riley Renaissance Composites, Inc. 3025 Airport Ave Santa Monica CA 90405 310.391.1943 "Who the hell wants to hear actors talk?" Jack Warner, 1928 See the Berkut at http://www.berkut.com Date: Wed, 21 May 1997 10:30:37 -0400 (EDT) From: DFinn7971@aol.com Subject: Re: COZY: Cozy: Misc Questions In a message dated 97-05-20 01:59:54 EDT, whittaker@mindspring.com (Glen E Whittaker) writes: << 1. Chapter 3, Page 3 says: "With BID the selvage is always removed". What happens if this edge is not removed? Basically you will get a bump that will require some extra filling. If you add a second layer of bid over the butted edges you will get some air bubbles that cannot be removed no matter how much stippling and squeegeeing you do. 2. Does it matter if slurry is cured or un-cured before performing a glass lay-up over foam? There was quite a discussion of this recently. Check the archives under Hard Shelling. Bottom line was that some people swear by it and some people are a little leery of doing it. Best to read the archives and your plans and make your own decision. 3. Can a scroll saw be used as a substitute for a band saw? >> It can be but a band saw is bunches better.be wary of using anything other then a fine tooth blade in the scroll saw as the reciprocating action will cause delaminations. But a band saw if you can. Try Harbor Freight Tools for a cheap one. If this is all you are going to do with it and are willing to take extra effort with set ups to assure accuracy you will probably find it adequate. Dick Finn Date: Wed, 21 May 1997 09:45:58 -0500 From: tpierce@ghg.net (Terence J. Pierce) Subject: COZY: BID at 45 degrees Someone told me that you could at one time buy BID from Alexander Aeroplane, that was rolled at 45 degrees. I called Aircraft Spruce East (old Alexander Aeroplane) and ask them, but the sales person knew nothing about it. If we could get BID at 45 degree roll, it sure would save a lot of wasted glass. The same person also told me about BID tape that was rolled at 45 degrees, for joints. All I could find was S2 glass tape at 45 degrees (Page 18 in AS&S catalog). Of course this stuff is expensive, 94 cents a foot for 3 inch wide. Can you use S2 glass tape with E-glass parts? And is it worth it? From: Lee Devlin Subject: Re: COZY: BID at 45 degrees Date: Wed, 21 May 1997 13:06:51 MDT > The same person also told me about BID tape that was rolled at 45 > degrees, for joints. All I could find was S2 glass tape at 45 degrees > (Page 18 in AS&S catalog). > Of course this stuff is expensive, 94 cents a foot for 3 inch wide. > Can you use S2 glass tape with E-glass parts? And is it worth it? That comes out to about $36/yd vs. $4-5/yd if you cut it yourself. I have had good results making corner tapes by sandwiching two large BID plies between 4 mil poly and wetting them out, drawing parralel lines on the top poly with a magic marker, and cutting them with a pizza cutter. The advantage of this is that it's very easy to handle since both sides have poly and it won't stretch. It's also easier to wet out in that the squeegy doesn't stretch the BID which I have found is a real problem on long thin BID at a 45 degree bias. Lee Devlin Date: Sat, 24 May 1997 15:56:55 -0500 From: ponciroli@postoffice.worldnet.att.net Subject: Re: COZY: Cozy: Misc Questions In an E-mail from Glen Whitaker, he asked >1. Chapter 3, Page 3 says: "With BID the selvage is always removed". What >happens if this edge is not removed? The selvage edge should be removed because it causes a ridge in the the surface of the lay-up, if you do not remove it when you are installing it, you probably will feel obliged to sand it off after it cures. > >2. Does it matter if slurry is cured or un-cured before performing a glass >lay-up over foam? The whole idea of the slurrey is to secure to glass layer to the foam. The slurry is the anchore that holds the glass to the foam. So yes it does matter. > >3. Can a scroll saw be used as a substitute for a band saw? It depends. For example, A band saw can be set up to do production work such as cutting the high density edge foam used in the sides and bottom of the airplane. This would be extremely difficult to do with a scroll saw. However, my wife claims that I have every tool known to man except that which I need to do the next job, but In my opinion, a man cannot have too many tools, or a car too fast, or woman too pretty. You get the idea. Have fun Glen. Don Ponciroli - ponciroli@postoffice.worldnet.att.net From: Epplin_John_A@hpmail1.90.deere.com Date: Wed, 28 May 97 14:31:44 -0500 Subject: COZY: composite layup in general I found a small firm locally that makes fiberglass tanks and plumbing pieces and parts. They were kind enough to spend some time taking me and a IA friend on a tour of their facility. Most of their work is for the chemical industry, corrosive material handling systems. They use vinyl ester and polyester resins with various glass material to custom build pipe up to 24" diameter and tanks over 1000 gallon capacity. or many of their products they use a heavy unidirectional cloth (a little thicker than the uni tape used in our cap strips) layed up at angles much the same way we do with wing skin etc. The major difference is they us a thin layer of random oriented fibers between lay-ups. I mentioned this and the reply was that the uni would de-laminate without the random fibers between layers. I wonder if anyone has any knowledge of this process. Is it only applicable to the heavy material or the resins they are using? They also use what they call a veil to get a smooth surface finish. It is a very loose random fiber mat about .1 in. thick. They saturate this with resin. This would be unacceptable for our purpose with the weight involved, but what if one used a mixture of Micro-balloons? I don't know why except maybe a technique could be developed to get a good finish without the pinhole problem. Just some random thoughts, it has been a boring afternoon at the office. John Epplin Mk4 #467 -- fussing with ailerons. From: "Kerry Lamb" Subject: Re: COZY: composite layup in general Date: Wed, 28 May 1997 16:35:21 -0400 > or many of their products they use a heavy unidirectional cloth (a little > thicker than the uni tape used in our cap strips) layed up at angles much > the same way we do with wing skin etc. The major difference is they us a > thin layer of random oriented fibers between lay-ups. I mentioned this and > the reply was that the uni would de-laminate without the random fibers > between layers. I wonder if anyone has any knowledge of this process. Is it > only applicable to the heavy material or the resins they are using? John, my background is dealing with various polyester type applications using everything from chopper gun to woven roving to hand layup in racing sailboats. The biggest reason they go with the heavy materials is stiffness (weight means less to them). The way you get the stiffness in our application is with the foam and the shape. Two other items of note: one: the omnidirectional mat they use between cloth layers soaks up bunches of resin, and two: the polyester resin system they use is far (far far) cheaper. Kerry Date: Thu, 29 May 97 09:20:22 EST From: "KEN SARGENT" Subject: Re: COZY: composite layup in general The main reason CSM (chopped strand mat) is used in-between layers is damage during point load incidents. This is why it has traditionally used in marine and other industries. i.e. crashing into docks, beaching, etc. For aviation used loading in mainly distributed aerodynamic forces. Except when I fly, I could have used some CSM in the wing tips, nose, and belly, or anything else I contact the runway with other than the gear. Polyester resin doesn't have some of the physicals you need to avoid exceeding interlaminer shear. And another reason you don't see Rutan adding CSM between layers in our plans is because he has "balanced the laminate", so that the plys are not fighting each other while they are loaded. In boat and pipe construction the shell elements sometimes have a combined loading that wants to pull the layers apart. The stringers of a hull do this pretty well sometimes. CSM is actually an attempt to nest the fabric together with short glass fibers. CSM by itself is pretty crappy with only 30% fiber content. Also, this industry typically makes shell elements that need thickness for strength, and CSM will get 0.047" a layer as apposed to 0.020" for woven roving. It also lays into a tool pretty well. And one other reason CSM is used is because polyester resin shrinks so much and the industry cures the material so rapidly that the fabric with draw on itself and you need CSM to absorb this. They will put 2-3 layers against the mold to avoid "print through". If you into boats this is one of those things people look at to find a good boat. I just like messing with boat salesman at boat shows. Now for veil, I use on molded parts a thin polyester veil (0.001") that is lightweight, chemically resistant, and basically reinforces the thin layer of resin that is on the surface of the laminate anyway. Even in open layup I find the veil helps to hold the weave down, and makes a more durable surface when cutting and trimming. Ken Sargent Cozy #555 Chp 7-9 Varieze 75EZ flying since 82 (landing gear three times) ______________________________ Reply Separator _________________________________ Subject: COZY: composite layup in general Author: Epplin_John_A@hpmail1.90.deere.com at DISNEY-WDW-INTERNET Date: 5/28/97 2:31 PM I found a small firm locally that makes fiberglass tanks and plumbing pieces .............................................................. a technique could be developed to get a good finish without the pinhole problem. Just some random thoughts, it has been a boring afternoon at the office. John Epplin Mk4 #467 -- fussing with ailerons. Date: Mon, 09 Jun 1997 11:25:51 -0500 From: tpierce@ghg.net (Terence J. Pierce) Subject: COZY: Chapter 5, big lay-ups Well, I got the inside of the fuselage lay-up done this weekend. Man, this was a lot of work. I had a total of 4 people, including myself, helping do this lay-up. It took us about 15.5 man hours to glass, put on upper longeron and peel-ply. I lost sometime fixing one of my helpers mess-up. I was having a hard time trying to get anyone to help me. I was about to try this with just my wife and I. Boy am I glad I waited for some help. Are there very many more long lay-ups like this? If I had to do this again, I think I might have done one side at a time. -- Terry Pierce e-mail: tpierce@ghgcorp.com Cozy Mark IV #600 From: Marc J. Zeitlin Subject: COZY: Chapter 5, big lay-ups (fwd) Date: Mon, 9 Jun 97 13:38:28 EDT Terry Pierce wrote; >..... I had a total of 4 people, including myself, >helping do this lay-up. It took us about 15.5 man hours to glass, put >on upper longeron and peel-ply Hmmm. Looking back over my logbook, I see that this layup took me about 14 person-hours (PC, you know :-) ), working with one complete novice (seven hours real time). Sounds about right, especially with a screw-up. >Are there very many more long lay-ups like this? There are a few. Shear web and spar caps in the canard (and wings), wing skins, fuselage exterior, strakes. The spar caps in the center section spar took the longest - 9 real hours - just me. >......... If I had to do this >again, I think I might have done one side at a time. Breaking these layups up is good. I get uncomfortable wearing the mask for more than 3 - 4 hours, and after 6 - 7, my concentration goes to hell in a handbasket. One of the advantages (not trying to start another flame war here :-) ) about hard-shelling is that it really allows you to break up these large layups into manageable chunks. For the skins with large areas of foam, I find that the microing of the surfaces can easily take half the time. I also find that I'm much more efficient working alone, and just asking my wife to give me a hand in some short, critical periods (suits her better, too). Otherwise, I spend half my time making sure everyone else is doing what they're supposed to be. Of course, I'm a control freak, so YMMV (Your Mileage May Vary) :-). -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Mon, 9 Jun 1997 16:36:29 -0400 (EDT) From: AlWick@aol.com Subject: Re: COZY: Chapter 5, big lay-ups In a message dated 97-06-09 12:34:43 EDT, you write: << Well, I got the inside of the fuselage lay-up done this weekend. Man, this was a lot of work. I had a total of 4 people, including myself, helping do this lay-up. It took us about 15.5 man hours to glass, put on upper longeron and peel-ply. >> Hey Terrence, you just got past one of the worst layups. Chapt 5 took me total of 63 hours. All layups can be done with one person, however fuse sides was one of the few times I had help placing cloth into position. Most layups can be broken up as needed. Long layups ahead (that should NOT be broken up) include spars, wings, canard. I've used every technique I know of to prevent myself from getting overwhelmed with the magnitude of the project. I finally have enough complete (almost looks like a plane) that it's not a problem anymore. Don't forget, you'll never have to do THAT layup again! Good luck -al sn 389 MKIV , 2.3 years down, 1.5 years to go. Date: Mon, 09 Jun 1997 17:14:41 -0700 From: Michael Antares Subject: Re: COZY: Chapter 5, big lay-ups Just to add to what others have said, I've found that my level of efficiency has markedly improved over the 2+ years that I've been working on the Cozy. For example, when I did the fuselage sides (even the bulkheads) I couldn't imagine what it would be like doing the wings. In those days I did a lot of stippling and less with the squeegee. Later on for the larger surfaces I did almost no stippling and all sqeegeeing. Also the faster you work the faster it goes and I don't mean just because of the time saved by working faster; it's also because the epoxy doesn't have a chance to get thicker and require lots more effort to get the glass wetted properly, and heat gunning, and...I also got a lot better at handling the glass and understanding how to get it in place without having to spend a lot of time straightening the fibers and how to get the BID cloth tucked into impossible corners without spending huge amounts of time. I've done all the work myself except at those critical times when someone needs to hold the other end of the cloth I yell for Susan and she's always right there ready to support so that's been a blessing. For me I think the worst layups were the spar caps, especially the main spar--get a good nights rest before taking that one on! Although even those became relatively easy by the last one. I haven't done the strakes yet so maybe my bad times aren't over yet! Anyway the bottom line is that it gets better and easier as the work progresses--at least until you get to the finishing. I haven't faced that one yet; others can answer, does sanding ever get easy? Regards, Michael 6077 Old Redwood Highway Penngrove CA 94951 707.792.7971 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 19 and 20. One wing/winglet finished, working on second. Date: Tue, 10 Jun 1997 21:58:28 -0400 (EDT) From: DFinn7971@aol.com Subject: Re: COZY: Chapter 5, big lay-ups In a message dated 97-06-09 12:34:50 EDT, tpierce@ghg.net (Terence J. Pierce) writes: << I had a total of 4 people, including myself, helping do this lay-up. It took us about 15.5 man hours to glass, put on upper longeron and peel-ply. I lost sometime fixing one of my helpers mess-up. Are there very many more long lay-ups like this? If I had to do this again, I think I might have done one side at a time. -- >> I don't remember it taking me that long. I did it with just myself and my wife. As a suggestion: 1. Make sure that you have everything set up before doing the layup (i.e. sand and vacumn the foam, round over edges, etc.) 2. For large layups - Mix up some stiff micro and fill any gouges in the foam first. - Mix large batches of slurry and squeegee it on. I don't think you wuill have to worry about an exotherm as you just pour the whole cup on and squeegee it around as soon as it is mixed. - I found I get better layups and it moves faster if I'm not stingy with the glass. I hang the bolt over the worktable and pull the glass out and drape it over the piece. I can then just tug it into position and cut off the excess. It wastes a yard or so on a large layup but it moves fast and the glass does not deform during the measure/cut/fold/unfold porcess. 3. Work with a friend or fellow builder. On my large layups I now work with another builder. We've gotten used to each other and seem to work as a team. 4. Mix large batches of epoxy and pour them on over a large area. On smaller layups I dribble it on but find it easier to quickly squeegee it out over a wide area before it really starts to soak in. Using a hair dryer allows you to squeegee out more or the excess. 5. When I started this out I made up a check list covering all the preparations. Its now second nature but the checklist helped in the beginning. I even included getting a soda with a straw and making a trip to the bathroom before donning gloves. Just some thoughts Dick Finn DFINN7971@AOL.COM Cozy Mark IV #48 Date: Thu, 19 Jun 1997 17:55:49 -0400 From: Jim Hocut Subject: COZY: Re: Cleaning before glassing > >What did you clean the glass/hard shell with, and would it work >with fiberglass? > Just a quick wipe with a clean cloth dampened with acetone to remove oils from my hands etc. I believe I remember hearing that suggestion here in regards to clean glass before secondary bonding. Jim Hocut jhocut@mindspring.com From: "Krasa-1, Paul" Subject: RE: COZY: Re: Cleaning before glassing Date: Fri, 20 Jun 1997 08:32:11 -0400 >---------- >From: Jim Hocut[SMTP:jhocut@mindspring.com] >> >>What did you clean the glass/hard shell with, and would it work >>with fiberglass? >> > >Just a quick wipe with a clean cloth dampened with acetone to remove >oils from my hands etc. I believe I remember hearing that suggestion >here in regards to clean glass before secondary bonding. I have always felt that acetone was a little strong and I worry about seapage into the foam, so I use a weak wipe down solvent used for cleaning surfaces prior to painting. Since this fluid flashes off rapidly, I feel it does not get down to the foam. Paul Krasa Long EZ 214LP Date: Fri, 20 Jun 1997 06:24:05 -0700 From: marcna Subject: Re: COZY: Re: Cleaning before glassing Krasa-1, Paul wrote: > > >---------- > >From: Jim Hocut[SMTP:jhocut@mindspring.com] > >> > >>What did you clean the glass/hard shell with, and would it work > >>with fiberglass? > >> > > > >Just a quick wipe with a clean cloth dampened with acetone to remove > >oils from my hands etc. I believe I remember hearing that suggestion > >here in regards to clean glass before secondary bonding. > > I have always felt that acetone was a little strong and I worry about > seapage into the foam, so I use a weak wipe down solvent used for > cleaning surfaces prior to painting. Since this fluid flashes off > rapidly, I feel it does not get down to the foam. > > Paul Krasa > Long EZ 214LP When I got started on my Cozy Mark VI, I placed a call to Hexel support Dept. with a few questions. I talked to the to a guy who started 20 years ago making and supporting RAE. He said the best prep before glassing to glass is a 50/50 mix of acetone and alcohol. Marc Parmelee N425CZ Date: Mon, 23 Jun 1997 20:27:21 -0400 From: Jim Hocut Subject: COZY: Premade BID tape revisited I was fiddling around with making a cover for my electric landing brake actuator, and actully came up with a variation on an idea that may be useful to others. To fasten the cover in place I am using "flanges" on the cover which will fit into a slot (front, top, and bottom), with the rear flange being drilled in a couple of place for screws. (This will allow it to easily slide out after the screws are removed). I totally trashed my first cover while making the slots out of BID tape. I had covered the flanges with duct tape (box sealing tape on the bottom), set the cover in it's final resting place, and put wet out BID tape in the proper position over the flanges. When it was all cured I had to pry so hard to get it to slide out that it was trashed. While in the process of re-making the cover (which turned out much nicer the second time - thank you), it dawned on me how I could apply what we've learned about pre-made BID tapes and do a really slick job of installing the slots. I measured the thickness of the flanges, and determined that 6 layers of duct tape would provide that thickness plus some tolerance for sliding in and out. I laid out the 6 layers of duct tape on a long piece of wax paper, and laid peel ply over the area. Then I laid out the BID tape w/ approx. 1/2 of it's width on the built up duct tape, wet it out, covered it with peel ply and wax paper, laid a long straight edge over the half of the tape at the lower elevation and weighted the straight edge. The cross section of the finished tape looks something like: ___________ __________| I hope this is explained well enough to be of use to someone, a picture is worth a thousand words and I don't have a scanner or digital camera yet (one of these days). -- Jim Hocut jhocut@mindspring.com Date: Tue, 24 Jun 1997 14:54:10 -0400 (EDT) From: AlWick@aol.com Subject: COZY: Glue method Just last night I was using a method to glue parts that works well. Never seen it mentioned before so thought I'd share it. This method intended for any time you need to glass around sharp corner. It replaces the need for cleco's too. In their place I've had good success by laying glass down, then peel ply. Next I place plastic over peel ply (so that next layer doesn't stick). Then use sponge type foam. You could use regular ol' house sponge if you want. Atop this I place a 1x2 piece of wood (so I have something to push against). Basically the sponge foam over the layup is used to compress the layup. It conforms to any shape. You can glass around sharp corners, etc. I used this for holding my interior components in position while glue dries. Armrests. Sometimes my sponge foam is 4" thick. I just wedge it in place, but always with a piece of wood between wedge and foam so my wedge applies an equal force over all areas of foam. Method works very well, but only local to the foam. Areas adjacent seem prone to lifting up. So use enough foam to cover entire layup. Really tough to explain this, hope it helps. -al From: michael.amick@nashville.com Subject: COZY: Epoxy-Brush in the freezer Date: Tue, 30 Sep 97 22:58:49 Organization: The Nashville Exchange-http://WWW.NASHVILLE.COM A while back someone made a post about using very few brushes on his project by "popping them in the freezer" until the next layup. I know that this would slow and almost stop the curing process but how do you use a frozen brush. If you heat it up again with a hair dryer etc. it seems that it would start the curing process where you stopped it and only give at best 1/2 life of the original cure time. Normally when I use a hair dryer the high temps 'Kick' the epoxy into curing quicker. Well, last week I popped mine in the freezer and I am ready to use it again. Is there any special rules for heating it up to working tempiture? How about reusing the small remaining epoxy for wetting out peelply or some other nonstructural use? michael.amick@nashville.com MkIV #317 Chapter 6 From: Epplin John A Subject: RE: COZY: Epoxy-Brush in the freezer Date: Wed, 1 Oct 1997 07:43:03 -0500 > A while back someone made a post about using very few brushes on his > project by "popping them in the freezer" until the next layup. I know > that > this would slow and almost stop the curing process but how do you use > a > frozen brush. If you heat it up again with a hair dryer etc. it seems > that > it would start the curing process where you stopped it and only give > at > best 1/2 life of the original cure time. Normally when I use a hair > dryer > the high temps 'Kick' the epoxy into curing quicker. Well, last week > I > popped mine in the freezer and I am ready to use it again. Is there > any > special rules for heating it up to working tempiture? > > How about reusing the small remaining epoxy for wetting out peelply or > some > other nonstructural use? > > michael.amick@nashville.com > MkIV #317 Chapter 6 > > [Epplin John A] Wrap the brush in saran wrap before freezing. Just take it out a few min. before you need it. I place mine in my heated epoxy cabinet for about 5 to 10 min. You can re-use several times depending on how long the brush sits before freezing it and how long it was in the freezer. It will eventually harden in the freezer. John epplin Mk4 #467 From: Howard Calk Subject: RE: COZY: Epoxy-Brush in the freezer Date: Wed, 1 Oct 1997 10:31:11 -0400 I keep an empty glass pickle jar (any jar will do a metal lid works best) which I put in some solvent (I use acetone). At the end of a lay-up I dip my brushes in the solvent and clean them as you would a paint brush then wipe them off well with a paper towel. You can get several uses from the brush using this method and the brushes will be almost as good as new after the cleaning. I put the lid on tight and save the used solvent in the jar until it gets too dirty then I throw it away. As for scissors, I also clean them off with solvent along with my squeegees after each lay-up session. This keeps them pretty much free of epoxy. Howard Calk Long EZ builder All chapters through canard construction completed. Elevators next. From: Lee Devlin Subject: COZY: Epoxy brush preservation Date: Wed, 1 Oct 97 11:13:40 MDT > > I keep an empty glass pickle jar (any jar will do a metal lid works best) which > I put in some solvent (I use acetone). I prefer to use a salsa jar which is tall enough to store the brushes with the lid on. I also use MEK which is slightly better at disolving epoxy and doesn't evaporate as readily. Just store your brushes in the jar with about 2 inches of solvent on the bottom and the lid secured. The brushes get better with each use in that they stop shedding bristles. I lost count as to how long they last. Lee Devlin From: AlWick@aol.com Date: Wed, 1 Oct 1997 14:36:49 -0400 (EDT) Subject: Re: COZY: Epoxy-Brush in the freezer In a message dated 97-10-01 00:07:23 EDT, michael.amick@nashville.com writes: << A while back someone made a post about using very few brushes on his project by "popping them in the freezer" until the next layup. I know that this would slow and almost stop the curing process but how do you use a frozen brush. If you heat it up again with a hair dryer etc. it seems that it would start the curing process where you stopped it and only give at best 1/2 life of the original cure time. Normally when I use a hair dryer the high temps 'Kick' the epoxy into curing quicker. Well, last week I popped mine in the freezer and I am ready to use it again. Is there any special rules for heating it up to working tempiture? How about reusing the small remaining epoxy for wetting out peelply or some other nonstructural use? >> No rules. Just use it. Better to not have gobs of epoxy on brush prior to freezing. I pull it out of freezer 5 min before using. As soon as you dip it in fresh epoxy it warms up and works just okey dokey. Very little thermal mass to brush. Enjoy! -al by InfoAve.Net (PMDF V5.1-8 #23426) with SMTP id <01IOAQQCBURA91AKRM@InfoAve.Net> for cozy_builders@hpwarhw.an.hp.com; Wed, 1 Oct 1997 15:55:57 EDT Date: Wed, 01 Oct 1997 15:50:00 -0400 From: Jeff S Russell Subject: Re: COZY: Epoxy brush preservation Organization: AEROCAD INC. Lee Devlin wrote: > I prefer to use a salsa jar which is tall enough to store the brushes > with the lid on. I also use MEK which is slightly better at disolving > epoxy and doesn't evaporate as readily. Just store your brushes in the > jar with about 2 inches of solvent on the bottom and the lid secured. > The brushes get better with each use in that they stop shedding > bristles. I lost count as to how long they last. Lee, I do the same but with laquer thinner. MEK can burn skin, eyes and has a low flash point (not good) but I use some on epoxy primer that's cured on my primer gun. Food for thought (salsa and brushes :-) -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com P.O. Box 7307 Port St. Lucie, Fl 34985-7307 Phone/ fax (call first): 910-961-2238 after Oct 31 561-460-8020 AeroCad: http://www.aerocad.com Composite workshop info: http://www.Sportair.com From: lschuler@cellular.uscc.com Date: Wed, 01 Oct 97 17:19:46 -0600 Subject: Re: COZY: Shop related --simple boundary Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Dick Finn wrote: >snip >As a side note, Two years ago I came across a fabric cutter at Oshkosh. It >basically is a plastic handle with a rotating disk blade. You just roll it >across the cloth and it gives a nice neat cut with no stetching. It cost >about $10.00. >I strongly recommend this cutter. Using a scissors distorts the cloth (not >a big deal I'll admit as you can pull it back into shape) while the cutter >leaves the cloth laying flat on the table with a beautiful cut. It is also >significantly faster. I just lay my straightedge across the cloth and run >the cutter along the edge -- no Magic Marker lines. I use the same cutter. My glass cutting table consists of a mahogany laminated solid 36" outside door I got for $8.00 at Menards (it was slightly damaged on one side). Set up on saw horses so it's 'relatively' easy to move out of the way or lay up against a wall or something. It's just plain heavy. I used 6 or 7 coats of polyurethane on top side to fill the grain and provide a super smooth surface to pull the glass across (I'm sure you all know how the glass latches on to just about any micro-protrusion it can find). The table (door) also doubles as a place to wet out all my 2" strips and other various layups. I use some rather inexpensive 3 Mil plastic over the table. Mark the "BOTTOM" side of the plastic with the size/shape of the glass to be cut with a wide black Sharpie. After drawing, flip the plastic over; this will keep the epoxy off the marker lines until everything is cut out. I use a few spots of cheap masking tape to hold the plastic at the corners and a few to hold the glass plies (i've cut up to 4 or 5 layers this way so far) over the marked lines. The glass is rough cut off the roll a bit oversized so the masking tape falls outside the lines. The tape keeps the glass from squirling around while wetting it out (all layers stacked and wet out simultaneously). The tape gets wet with epoxy and eventually would let lose, but it holds much longer than needed. Once wet out the lines are visible through the glass. I cut through the glass AND plastic with the rotary. The plastic helps keep everthing together when transfering to the plane and also helps keep the glass from squirling around while squeegeeing (if that's a word). Makes the air bubbles more visible too. I remove the plastic and then stiple as needed, followed by peel ply. I peel ply everything. The rotary cutter is disassembled and cleaned with paper towels after each session and then set aside to cure disasembled. Seems to stay very sharp through multiple sessions. I found a blade sharpener at the local fabric store and use this occasionally the sharpener cost more than the original cutter, but seems to have been a good investment. Used the same cutter and blade now for about two years. Cost me about 10 bucks in the flymarket as I recall. The fabric store had similar ones for a LOT more. Bought two more this year, just in case and decided to use one for the rough-cuts only. Second new one is a spare. Still using original. I only keep a small pair of scissors for wet glass for trimming and nipping corners etc. A second, no-epoxy, rotary cutter is used for rough-cutting the glass (also on the same table). Scissors are cleaned with paper towels after each session and set asside (open) to cure. I use a knife to scrape the cured epoxy off just before a session. Only had to sharpen them once (dropped them on the floor and one blade got a nick from the other blade, so had to smooth it out). I do have a big pair of scissors for cutting glass on the table which come in handy for quick snips of the scraps (used to make smaller layups) etc. Sharpened twice with a file and wet stone in two years. The darnd angle changes acrosse the blade, so it takes a bit of care. At the end of the session, the remaining plastic is removed from the table and paper towels used to clean up. I found that the epoxy cleanup is handy for filling the gouges in the soft mahogany wood made by the rotary cutter. By next day the epoxy left on the door is set enough to do next session. Once in a while I run a sanding block over the door to take care of rough spots (found after pulling glass across it of course!) After a couple years, it's about time to coat the whole thing with a thin coat of epoxy (left-over stuff of course). The door also doubles as my flat surface for bulkheads etc.. ensures that everything is perfectly flat. This was the primary reason I went with an outside-type, solid-core door. They are about as flat as a pancake and don't "usually" warp. Took quite a few trips to Menards to get the damaged one (i'm cheap) I wanted. Have also used it for vac baging using silicone caulk for sealing the bag plastic directly to the table. I can pull 15" to 20" (that's about 7.5 to 10 lbs per sq inch which is MORE than enough) vaccuum directly on the table. I think the initial coats of polyurethane did the trick on sealing the wood. Sure, it leaks a bit, but as long as I lay down a sheet of plastic (3 mil) a bit bigger than the layup, but smaller than the bag, with release and bleeder in the gap, I can ensure that the leaking air through the wood goes through the gap and not through the layup. Works too. The only pin hols I do get are from pulling too much vaccuum and pulling the gasses out of the foam. The caulk peels right off when done and is one heck of a lot cheaper than the recommended sticky tape. Only a couple cautions: 1. Some caulks make more of a mess than others and some won't peel off as well until they are fully cured. The middle of the road silicone types seem to work best. The expensive ones take too long to cure. The cheap latex ones are messy, but cure quicker. Experiment untill you are happy. 2. Epoxy sticks like crazy to sanded urethane; or, maybe it's the other way around. Use plastic. My first vaccuum attempt was without plastic under the layup. Bit of a disaster. (I kept the door, but had to sand, fill and urethane the other side). A bit long winded, but hope this hleps someone. Larry Schuler #500 ch-10 lschuler@cellular.uscc.com --simple boundary Content-Type: text/plain; charset=US-ASCII; name="RFC822.TXT" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="RFC822.TXT" Received: from gatekeep.uscc.com by cellular.uscc.com (ccMail Link to SMTP R8.00.01) ; Wed, 01 Oct 97 07:43:36 -0600 Return-Path: Received: from www.uscc.com (www.uscc.com [204.179.101.2]) by gatekeep.uscc.com with ESMTP id IAA27887 for ; Wed, 1 Oct 1997 08:39:59 -0400 (EDT) Received: from palrel1.hp.com (palrel1.hp.com [156.153.255.235]) by www.uscc.com with ESMTP id HAA17550 for ; Wed, 1 Oct 1997 07:40:44 -0500 (CDT) Received: from hpwarhw.an.hp.com (hpwarhw.an.hp.com [15.57.193.122]) by palrel1.hp.com (8.8.6/8.8.5tis) with SMTP id FAA13099 for ; Wed, 1 Oct 1997 05:42:47 -0700 (PDT) Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA01785; Wed, 1 Oct 1997 08:41:46 -0400 Received: from hp.com by hpwarhw.an.hp.com with SMTP (1.37.109.8/15.5+IOS 3.22) id AA01780; Wed, 1 Oct 1997 08:41:45 -0400 Received: from emout19.mail.aol.com (emout19.mx.aol.com [198.81.11.45]) by hp.com (8.8.5/8.8.5tis) with ESMTP id FAA13487 for ; Wed, 1 Oct 1997 05:39:43 -0700 (PDT) From: DFinn7971@aol.com Received: (from root@localhost) by emout19.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id IAA14815; Wed, 1 Oct 1997 08:37:04 -0400 (EDT) Date: Wed, 1 Oct 1997 08:37:04 -0400 (EDT) Message-Id: <971001083641_440596461@emout19.mail.aol.com> To: imartin@indy3.gstone.com, cozy_builders@hpwarhw.an.hp.com Subject: Re: COZY: Shop related Sender: owner-cozy_builders@hpwarhw.an.hp.com Precedence: bulk Reply-To: DFinn7971@aol.com --simple boundary-- Date: Thu, 02 Oct 1997 11:51:04 -0700 From: "LCDR James D. Newman" Organization: INFINITY Aerospace - http://www.flash.net/~infaero Subject: COZY: Re: Shop related Hi Dick and All, >I strongly recommend this cutter. Using a scissors distorts the cloth (not a big deal I'll admit as you can pull it back into shape) while the cutter leaves the cloth laying flat on the table with a beautiful cut. It is also significantly faster. I just lay my straightedge across the cloth and run the cutter along the edge -- no Magic Marker lines.< So that the cloth does not distort, after laying out the cloth so it's not skewed, I put a 1/2" wide piece of mashing tape down the 45 degree line of BID (or what ever I'm going to cut) and cut down the center of the masking tape, leaving the 1/4" wide masking tape in place. This keeps the cloth from skewing all over the place when I cut out a section, and keeps the edge(s) of the roll from un-raveling where you cut. Or, I lay the cloth on aluminum foil for 2" wide BID tapes, or on 4 mil plastic with the patterns I want, then lay up the plys onto the foil or the plastic. Cut the foil or plastic and the wetted out cloth, place the tapes or the pattern, and squeegy it down from the foil or plastic side. Then peel the foil or plastic off and peel ply. You can make a light weight part sqeegying on the foil or plastic. Since the BID tapes, for example, do not get skewed from the 45 degree, you get a stronger part, and it's less work 'cause you don't have to try and straighten things out. The 'pizza cutters' do work great. HTH. Infinity's Forever, JD From: guy.terren@dl20.laposte.telepost.fr Date: Tue, 7 Oct 97 07:10:32 +0000 --openmail-part-0007c96c-00000001 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hello All, Has some one a scientific explanation for the removing of cross stitchin= g threads when using UND tape ?? thaks for an answer G.TERREN --openmail-part-0007c96c-00000001 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable =0D [IDENTIFIER]=0D VERSION=3DV2_0_0=0D =0D [MESSAGE]=0D CB=3D2=0D --openmail-part-0007c96c-00000001-- From: Marc J. Zeitlin Subject: COZY: UND tape cross stitching Date: Tue, 7 Oct 97 10:26:23 EDT Guy Terren wrote: >Has some one a scientific explanation for the removing of cross >stitching threads when using UND tape ?? Scientific? I don't know, but here's how I did it (pretty much by the manual, I think). [I assume you're talking about the 3" wide spar cap UND tape here, and not the 38" wide UNI glass cloth, right?]. After laying down a coat of epoxy and then the UND tape, I snipped the blue thread (the plastic one all the way to one side of the tape) in the middle of the tape. I then pulled the blue thread out from either end of the tape, making sure to hold the glass down so as not to pull it out of the trough. The cross-stitching then pulls out easily - just grab hold of one end, use your other hand to hold the tape down in the trough as you pull gently on the cross stitching, and out it comes. There will be some epoxy on it, so you'll get all gunked up. Once the threads are out, you will add more epoxy and then squeegee the heck out of it to pack the trough, saturate the glass, and remove excess epoxy. Use a hair dryer to help wet out the glass. -- Marc J. Zeitlin Email: marcz@an.hp.com From: "norm & monda" Subject: COZY: Re: Date: Tue, 7 Oct 1997 10:30:13 -0400 yeah the tape is polyester and the epoxy doesnt actually bond to it. plus the fibers need to be straight and flat for the best strength. norm & monda cozy IV #202 ---------- From: guy.terren@dl20.laposte.telepost.fr To: cozy_builders@hpwarhw.an.hp.com Subject: Date: Tuesday, October 07, 1997 3:10 AM Hello All, Has some one a scientific explanation for the removing of cross stitching threads when using UND tape ?? thaks for an answer G.TERREN [IDENTIFIER] VERSION=V2_0_0 [MESSAGE] CB=2 ---------- Date: Tue, 07 Oct 1997 21:12:30 -0700 From: C Van Hoof Organization: Architect Subject: COZY: UND cross stitching Hi All, The matter of the UND cross stitching depends very much on who the supplier is (amongst a boatload of other things:-)). My UND tape came as a 95/5% weave. Means two things to me: Watch that the correct weight is used in the direction required. Don't take the crossthreads out because they are fibres and cling well. there is no means of removing these without disturbing the balance(95%) to such an extent that i wouldn't use the part.... The USA UND may differ (as i read from your reports) You can also build your very own rovings machine - see some newsletters ago (pic)- Rego Burger built it...he's on holiday now, but just maybe will tell some more... There are also 3" UND tapes available which are prepreg material, a bit of a stinker to wet out and they don't take to bends very well. just another opinion. chris #219 Date: Wed, 8 Oct 1997 02:37:26 -0400 From: Eddie Vann <100740.3723@compuserve.com> Subject: COZY: Cross stitching of 3in tape. The long-Ez plans do not call for removing the thread which holds the 3 inch roving tape for the spar caps together. I remembered, however, about= a British built sailplane called Torva which apparently had spar caps of glass banadage. (Perhaps the same tape, I don't know) The technical peopl= e doing the certification of this machine flagged this up as a potential problem since previous fatigue experience with glass aircraft was limited= to those with spar caps of glass rovings laid straight, whereas the presence of the thread in the "bandage" must transform a small amount of the compression and tension in the glass to bending. This, plus the fact that the thread weighed something, however little, and made no contributi= on to the airframe once installed led me to remove the tape in the way described by Marc. The time spent removing it is not negligible but it seemed easier to obta= in a "tidier" layup of the tape which made subsequent finishing simpler. Eddie Vann, Long-Ez F-PGEV 100740,3723@comp=FBserve.com Date: Wed, 22 Oct 1997 09:57:32 +0200 From: Rego Burger Subject: COZY: Delamination Caution Most work to a high level of workmanship but I felt lead to encourage builders to beware of voids or air bubbles under otherwise airtight areas. eg. Take a three ply surface. You get the first two plies 100% but because it's late at night the third ply got a few air bubbles ( blisters ) anything bigger than a 8mm radius. These are often visual but can be tapped - audio traced. The sound is a dull thud. The scenario. A bubble under the skin if it has no breather hole at sea level will want to expand with a rise in altitude, especially if it's at a fast rate of climb. This is another good reason ( not the only ) why fuel tanks are vented. If you look at the Cozy Strakes there is a vent hole on the outboard extremity where the transition block of uthane goes on. Besides a water drain or accidental fuel drain it serves the same purpose in preventing altitude expansion. The solution: The least you can do to stop the delam is to prick a pin hole in it to allow pressure regulation. The best is to fill with resin. On big surfaces 10mm rad. and up a 1/8" hole will eventually fill up with squeegee . If it's really bad it must be repaired. Sand away add enough plies to replace with a 1" overlap, peel ply. OPINION: I think this repair looks much better than a rivetted plate on a crack on a ali kite...:-) Good Luck Rego Burger CZ4#139 RSA http://home.intekom.com/glen/rnb.htm Date: Thu, 13 Nov 1997 07:40:56 -0600 (CST) From: Tom Brusehaver Subject: COZY: Glass Stretching Last night I did the landing gear hardpoint layup, the one with 22 plies of BID. I figured something out, that I noticed before, but didn't understand. I cut the cloth on the cutting table in one room, and carry the cut pieces very carefully into the other room, and they shrink! Well, last night when I was measuring everything with a ruler, I figured it out. The glass relaxes maybe after being cut, so it isn't as long as it was when I cut it, but rather wider (length in the direction rolled, width in the width of the roll). I was able to get my size back by twisting the pieces, but now I worry I have compromised the integrety of the fabricated parts. Am I in trouble, are the parts potentially weaker? Is there a way to prevent this? As I pull the cloth off the roll, I usually pull some slack, and then work it out on the cuttin board, smoothing it out, and trying to let it relax, but maybe not enough. From: "Fred I. Mahan" Subject: Re: COZY: Glass Stretching Date: Thu, 13 Nov 1997 09:17:08 -0500 Not a worry, the glass strands per square inch are about the same. Next time, allow a little extra glass when laying out what you need for your bid parts. When you mark your cuts, put a piece of 3/4" to 1" wide masking tape over the line. Cut through the middle of the tape, and you have a piece of bid resistant to getting out of shape when you carry it from room to room. This is not original -- others smarter than me came up with it. Fred in Florida ---------- > From: Tom Brusehaver > I cut the cloth on the cutting table in one room, and carry the cut > pieces very carefully into the other room, and they shrink! >snip< > Am I in trouble, are the parts potentially weaker? Is there a way to > prevent this? From: SBLANKDDS@aol.com Date: Thu, 13 Nov 1997 10:37:39 -0500 (EST) Subject: Re: COZY: Glass Stretching In a message dated 97-11-13 08:56:31 EST, you write: << Last night I did the landing gear hardpoint layup, the one with 22 plies of BID. I figured something out, that I noticed before, but didn't understand. >> You can not stretch glass, you can only change the orientation of the BID, from perpendicular to oblique. Hint: Make the 22 layers larger by and inch or so you don't come up short... Steve Blank Cozy Mark IV #36 Date: Thu, 13 Nov 1997 13:38:57 -0800 From: "LCDR James D. Newman" Organization: INFINITY Aerospace - http://www.flash.net/~infaero Subject: COZY: Re: Glass Stretching Hi Tom and All, >Tom Brusehaver wrote:< >Is there a way to prevent this?< Yes, mark aluminum foil with the rectangles you want, lay out the plys at the orientation desired, do the lay ups on the aluminum foil, cut the foil and the plys all together, and transport the plys on the aluminum foil to the work. Flip it over and put down the plys, squeegy on top the aluminum foil, peel the foil off, squeegy out the excess resin, repeat or peel ply when done. The aluminum foil keeps the plys from skewing and the finished part will be stronger. I use aluminum foil for corners and compound shapes, and a ~4 mil thick plastic for flat/near flat lay ups. See the archives for more detail. Infinity's Forever, JD From: "Neal Newman" Subject: Re: COZY: Re: Glass Stretching Date: Thu, 13 Nov 1997 21:47:45 -0500 when I was Building the Cozy III instead of using aluminum foil which wrikles. I used Visqueen...its a clear plastic like used for covering upholstry... or it can be bought from any Home depot.. its also used on construction sites.. whats nice about visqueen is that you can see if you are squeeging out to much resin from the layups... and see if there are any air bubbles.. I also used it for vacum forming some components.. Neal Newman BTW thanks to john and paul. you guys know who you are. The wife is allowing me to start the Mk4 project..( SO SHE SAYS we will see) ---------- > From: LCDR James D. Newman > To: Canards - 'R' - Us > Subject: COZY: Re: Glass Stretching > Date: Thursday, November 13, 1997 4:38 PM > > Hi Tom and All, > > >Tom Brusehaver wrote:< > >Is there a way to prevent this?< > > Yes, mark aluminum foil with the rectangles you want, lay out the plys > at the orientation desired, do the lay ups on the aluminum foil, cut the > foil and the plys all together, and transport the plys on the aluminum > foil to the work. Flip it over and put down the plys, squeegy on top > the aluminum foil, peel the foil off, squeegy out the excess resin, > repeat or peel ply when done. The aluminum foil keeps the plys from > skewing and the finished part will be stronger. I use aluminum foil for > corners and compound shapes, and a ~4 mil thick plastic for flat/near > flat lay ups. See the archives for more detail. > > > Infinity's Forever, > > JD > From: DFinn7971@aol.com Date: Fri, 14 Nov 1997 15:46:07 -0500 (EST) Subject: Re: COZY: Glass Stretching In a message dated 97-11-13 08:56:31 EST, tomb@augusta.netperceptions.com writes: <<=20 Am I in trouble, are the parts potentially weaker? Is there a way to prevent this? As I pull the cloth off the roll, I usually pull some slack, and then work it out on the cuttin board, smoothing it out, and trying to let it relax, but maybe not enough. >> I wouldn=92t worry about having to tug at the cloth to get it back into s= hape after moving it from the cutting table to the glassing area.. In some ar= eas this wouldn=92t matter but, as a rule of thumb, You probably should make = an effort not to stretch a small piece out of shape in order to fit a larger area. Over the past six years I=92ve found that there are a number of tricks to working with the glass. Most have been mentioned in the COZY list in var= ious postings. I=92ll note a few below and possibly others would like to add = their ideas. Some of the new builders may benefit. 1. Keep the cutting area clean. 2. Cut oversize. 3. Instead of using a marker, use masking tape to mark where you will be cutting. I lay out a straight edge about .5 inches from where the cut wi= ll be and lay the tape along the edge. Cut right up the center of the tape. The tape will help keep the pieces from deforming. 4. Use one of the pizza cutters (rotary cutter =96 about $10). I got mi= ne at Oshkosh but I think they are available in the Wicks or AS&S catalogue. Y= ou can run the cutter along a straight edge and cut without deforming the cl= oth. I find its easier then using a scissors. 5. Fold the cloth carefully into a small packet before transporting it. = Get in the habit of folding the cloth in the same way each time so that you c= an position the folded bundle on the foam and carefully unfold it so that it covers properly. 6. I found it was not worthwhile to be stingy with the cloth. I cut oversize. That way I=92m not pulling and tugging to get a piece that bar= ely fits exactly into position. With less positioning the better the strands will lay straighter. 7. On my first large lay-ups (fuselage sides), I cut the pieces and positioned them on the foam. This was a lot of extra work and resulted i= n spending extra time during the lay-ups. Time is at a premium as you do n= ot want the epoxy to start setting up before you finish. Now I hang the bol= t of cloth over the part and simply pull out the cloth and drape it over the p= art. Its easier to position with minimal tugging and it goes fast. I trim oversize with a scissors and trim it after the epoxy partially cures. I = am guessing that I wasted about one or two yards over both wings (less then = $10) doing it this way. 8. If you cut off a clean odd size piece of cloth when trimming or cutti= ng, fold it neatly and put it away. There are a lot of uses for these pieces. Dick Finn From: "Fred I. Mahan" Subject: Re: COZY: Glass Stretching Date: Fri, 14 Nov 1997 18:10:27 -0500 Dick Finn wrote: >snip< 4. Use one of the pizza cutters (rotary cutter =96 about $10). I got mi= ne at Oshkosh but I think they are available in the Wicks or AS&S catalogue. Y= ou can run the cutter along a straight edge and cut without deforming the cloth. I find its easier then using a scissors. >snip< Wal-Mart has 'em, too. Look in the sewing section and get one with a tungsten blade. I think Olfa is the name. Fred in Florida From: cdenk@ix.netcom.com Date: Fri, 14 Nov 1997 18:51:11 -0600 (CST) Subject: Re: COZY: Glass Stretching More glass tips: 1: THe pizza cutter is available at most places that have sewing supplies. 2: I like cutting the fabric before mixing epoxy, laying it on the foam, marking some key edges, corners, etc with a felt tip pen, roll or fold in a fashion to be able to unfold in near exact location. Then after spreading the micro, it makes laying out the glass quicker. 3: Have all pieces, tools, supplies laid out ahead of time, many times I would the night before. Date: Sat, 13 Dec 1997 16:58:14 -0500 From: Ian Douglas Organization: WTC Subject: COZY: Laminations Hi All, I have just finished all of the hard points on the wings and was testing the bond between the two BID layers (Access recesses in wings near shear web). After cutting off the excess I figured I would see how hard it was to pull the two pieces apart. I was able to do it with my bare hands! Is this normal? Where the pieces separated one piece of cloth ripped but after testing all of the leftovers I was able to pull them all apart (I did have to start one with pliers). I'm using Aeropoxy... -- Ian MK0069 From: "norm & monda" Subject: Re: COZY: Laminations Date: Sat, 13 Dec 1997 20:54:26 -0500 oh boy. NOT good you should NOT be able to pull the layups apart by hand. mabey with pliers and a lot of pulling but NOT by hand. norm & monda cozy IV #202 From: Marc J. Zeitlin Subject: COZY: Laminations (fwd) Date: Sat, 13 Dec 97 21:43:22 EST Ian Douglas writes: >.... After cutting off the excess I figured I would see how hard it >was to pull the two pieces apart. I was able to do it with my bare >hands! Is this normal? No, and not good. >......... Where the pieces separated one piece of cloth >ripped but after testing all of the leftovers I was able to pull them >all apart (I did have to start one with pliers). I'm using Aeropoxy... This sounds like the same problem I had (and other's have had) with the 2427 epoxy. Under certain conditions, it did not bond well at all. I was able to pull the same reinforcements off after laying up my main spar. I found that if I allowed the 2427 to start to "kick", and then tried to lay up more epoxy over it, it would NOT bond at all. I had to make sure that I had a non-jelling 2427 layer to layup over, so I either had to work in cooler temperatures or else work faster. I went back and tested my previous layups, only found one that had the same problem, and redid it (as well as the hard point layups). After that, I ensured that I NEVER tried to layup on "kicked" 2427 - I would just stop and layup after it cured (after sanding). I've never used the Aeropoxy, but it sounds like a similar problem - the 2427 was also sensitive to humidity - I don't know if the Aeropoxy has the same problems. Now that I'm using the EZ10/84, this problem is gone (but it stinks to high heaven :-). I'd go back and test a few of your other layups, and redo any that peel this easily. Then do some experiments to determine why it happened, or else switch to the EZ10/84. Good luck. -- Marc J. Zeitlin Email: marcz@an.hp.com From: Epplin John A Subject: RE: COZY: Laminations Date: Mon, 15 Dec 1997 10:24:51 -0600 > -----Original Message----- > From: Ian Douglas [SMTP:douglas@ibm.net] > Sent: Saturday, December 13, 1997 3:58 PM > To: Cozy Builders > Subject: COZY: Laminations > > Hi All, > > I have just finished all of the hard points on the wings and was > testing > the bond between the two BID layers (Access recesses in wings near > shear > web). After cutting off the excess I figured I would see how hard it > was to pull the two pieces apart. I was able to do it with my bare > hands! Is this normal? Where the pieces separated one piece of cloth > ripped but after testing all of the leftovers I was able to pull them > all apart (I did have to start one with pliers). I'm using > Aeropoxy... > -- > Ian > MK0069 [Epplin John A] Ian & all: I have been using Aeropoxy since 2427 became unavailable. One thing I noticed is the slow cure time. If your were examining your work less than 48 hours since lay-up, even at 80 deg. f, it doesn't surprise me that you were disappointed. Try it again after a week or so cure. This may not be the case, just my .02 worth John epplin Mk4 #467, building turtleback. Date: Mon, 15 Dec 1997 15:42:25 -0500 From: Ian Douglas Organization: WTC Subject: COZY: Vacuum Bagging Hi All, Anyone know the Hg (inches of mercury) required for vacuum bagging? After talking with AEROPOXY tech. support, they informed me that I need to get between 25 to 27 Hg. This seems quite high as I was reading where people where only using 5 to 7 Hg. Also I understand that there is a plastic perforated layer required on top of the peel ply that burlap or something equiv. will go on. Does anyone have more info on vacuum bagging (I want to do the wings, canard, and winglets)? I looked in the archives but there does not appear to be a vacuum bagging file. -- Ian D.S. Douglas TEL (613) 599-5046 Director of Technology CEL (613) 724-6382 Workplace Technologies Corporation FAX (613) 764-3280 135 Michael Cowpland Drive INET douglas@ibm.net Kanata, Ont. Canada K2M-2E9 Date: Mon, 15 Dec 1997 15:50:53 -0500 From: Ian Douglas Organization: WTC Subject: Re: COZY: Laminations (fwd) After talking with Aeropoxy tech support, it would appear that I needed to wait a longer period of time before doing my peel strength tests (I was testing one day after the layup). It requires a week for a full cure with Aeropoxy. I have doen a 6 ply test piece that I am leaving down by the wood stove (about 120 degrees F) for a week. I will then test for peel strength. I was also informed that a 150 deg. F post cure would be a VERY GOOD idea as it will give me the best results. -- Ian MK0069 Date: Mon, 15 Dec 1997 16:38:35 -0500 From: Ian Douglas Organization: WTC Subject: Re: COZY: Vacuum Bagging John, Thanks for the numbers re bagging foam, I was sure that they where high (OK for a mold maybe). > Just got your message concerning cure from Aeropoxy. I cured > some small brackets I made in my epoxy cabinet, kept at 100 F.. These > seemed near max strength after 24 hours, at least they sanded well and > seemed hard. When I sanded and cut the excess glass off it sanded normally and seemed quite hard. I have one of the cut offs down in my office that I will test wednesday. I also have a 6 ply test layup sitting in my "in" basket that I will test next sunday. I noticed numerous "micro" bubbles in the bond and the tech guy told me that they would also contribute to low peel strength. The reason I did a 6 ply test was that tech support stated that the peel strength test with two plies would not be very good. -- Ian D.S. Douglas TEL (613) 599-5046 Director of Technology CEL (613) 724-6382 Workplace Technologies Corporation FAX (613) 764-3280 135 Michael Cowpland Drive INET douglas@ibm.net Kanata, Ont. Canada K2M-2E9 Date: Mon, 15 Dec 1997 17:13:39 -0500 (EST) From: Nigel Field Subject: RE: COZY: Laminations At 10:24 AM 12/15/97 -0600, John epplin wrote: in response to Ian's delam question: > > > > I have been using Aeropoxy since 2427 became unavailable. One >thing I noticed is the slow cure time. If your were examining your work >less than 48 hours since lay-up, even at 80 deg. f, it doesn't surprise >me that you were disappointed. Try it again after a week or so cure. >This may not be the case, just my .02 worth > Good point here John, I was going to post the same. I found the same with epolite 2184/2410 (safety poxy II), that it has to almost fully cured to reach full peel strength. A 24 hr RT cure will have poor peel strength. Takes 4 or 5 days then it wont peel, even stronger after 2 to 3 weeks. Seems Aeropoxy is similar as you state. Nigel Field Date: Mon, 15 Dec 1997 16:25:23 -0600 From: Chris Anderson Subject: Re: COZY: Vacuum Bagging At 03:42 PM 12/15/97 -0500, Ian Douglas wrote: >Hi All, > >Anyone know the Hg (inches of mercury) required for vacuum bagging? >After talking with AEROPOXY tech. support, they informed me that I need >to get between 25 to 27 Hg. This seems quite high as I was reading >where people where only using 5 to 7 Hg. Also I understand that there >is a plastic perforated layer required on top of the peel ply that >burlap or something equiv. will go on. Does anyone have more info on >vacuum bagging (I want to do the wings, canard, and winglets)? I looked >in the archives but there does not appear to be a vacuum bagging file. Andrew Marshall points out 13psi (26 Hg) as a pratical max vacume at sea level. I think the folks are assuming you have a industrial/lab grade vacume pump. That's a bit much. (page 7-19 Composite Basics 4th ed.) ============================================================== ...because our country will inevitably proceed down the path marked by the ideas of Robert Heinlein. That's legacy enough for any man. He showed us where the future is. It's our job to go and make it. --Tom Clancy, of Robert A. Heinlein Chris Anderson andersoc@idcnet.com KA9UQO From: Howard Calk Subject: RE: COZY: Vacuum Bagging Date: Mon, 15 Dec 1997 17:37:24 -0500 The amount of vacuum you can pull on a part depends on the part itself. On foam such as is used for the canard and wings, we typically pull around 13 to 15 inches Hg. If there are conduits, etc, in the structure you may need to pull less (5 -10 inches) so you avoid crushing the foam structure. The use of cull plates to protect the thin areas of foam can help. For flat pieces using high density foam, you can pull 25 to 27 inches without damaging the structure. The method we use is release ply, bleeder ply, and then the bag. You do not need the perforated plastic unless you are doing parts with close complex curves (release ply does not conform well). You will not need it for the wings and winglets. The only part of the canard we found could be easily vacuum bagged was the spar caps. Note that we also carbon fiber tapes and the lay-up schedule called out for the Berkut. For bleeder, we use a material which is similar to polyester blanket fill. Uncompressed, it is about a quarter inch thick. Also note that all of the above discussion applies to parts not made in a mold. Howard Calk Long EZ builder Date: Mon, 15 Dec 1997 22:42:30 -0500 From: Jim Hocut Subject: Re: COZY: Vacuum Bagging >>Anyone know the Hg (inches of mercury) required for vacuum bagging? I normally use about 8 - 10 inches. I've experimented some and it seems that after that you have a case of diminishing returns as far as weight savings. >> Also I understand that there >>is a plastic perforated layer required on top of the peel ply that >>burlap or something equiv. will go on. Depends on what type of peel ply you use. Wicks and AS&S have started to carry a peel ply that's treated with a release agent so that you don't need any perforated sheet. If you use untreated peel ply, then yes you will need the perforated release sheet, or else face a REAL difficult time prying everything off the layup (been there). >>Does anyone have more info on >>vacuum bagging (I want to do the wings, canard, and winglets)? I looked >>in the archives but there does not appear to be a vacuum bagging file. > I've been doing quite a bit of vac bagging, suggest you start with the easy (flat) pieces first. The bulkheads are quite easy, and you can save several pounds there. I also did the inside layups on the fuselage sides and bottoms, somewhat more tricky but still manageable. Between the bulkheads and interior layups I got a fuselage weight of about 77 pounds after ch. 7. BTW, you don't need the expensive valves etc. that are shown in the catalogs. A guy from NASA was at OSH a few years ago, and showed us how you just lay a little extra bleeder material next to the layup, bring the vac. line over to it, and seal it down. I also keep a tube of the cheapest latex caulk I can find on hand for sealing leaks and hard to get to creases and seams, much easier than fighting with that sealing tape. I also use approx 3 mil thick plastic sheeting from the local hardware store instead of the high priced material in the catalogs. I use the white masonite material sold for bathroom use as a base, it's only $7 or $8 per sheet and lasts quite a while. If it gets scratched up it won't hold a vacuum so you can move to another area on the same sheet. The brown masonite won't seal worth a darn (I found out the hard way of course). Jim Hocut jhocut@mindspring.com Date: Wed, 17 Dec 1997 09:55:25 +0200 From: Rego Burger Subject: COZY: Impact tests Hello Group, With fears of lamination or rather De-lamination... I was wondering if anyone has done any impact tests on a L.E. structure for interest to simulate a bird strike or hail? @ 180mph it could be a serious thump! I feel under normal flight operation most resins will hold their own but those with poor adhesion qualities would be the first to promote De-lam after a crushing blow! I don't want to waste time with tests of this nature if they've been done before. I'd rather build on the Cozy...well almost Cozy! ( I did modify the canpoy and turtledeck ) :-) Rego Burger web site: http://home.intekom.com/glen/rnb.htm home e-mail: mailto:rnb@intekom.co.za Date: Thu, 18 Dec 97 05:50:23 EST From: "KEN SARGENT" Subject: Re: COZY: Vacuum Bagging 28 inches max depending on the pump. Good rule of thumb is to pull up on a crease in the bag, and if you can't lift it up and move the bag over, you have close to 20. I like this method since you can not put gauges everywhere. 20 is plenty on a flat laminate, 5-10 will distort the 2-4 pcf foam. Use the bleeder (perforated plastic) on top of peel ply, the breather on top of that. Peel ply then breather somtimes draws to much resin out of the laminate. An air leak will also create an "embolism" and dry out the laminate. Ken Sargent Cozy Plans #555 ken-sargent@wda.disney.com ______________________________ Reply Separator _________________________________ Subject: COZY: Vacuum Bagging Author: Ian Douglas at DISNEY-WDW-INTERNET