From: Lee Devlin Subject: Re: The mailing list Date: Mon, 30 Jan 95 15:50:08 MST Hi Marc, > Interesting. I posted to r.a.h a few weeks ago, and I KNOW that some > people saw it. Ce la vie. I could post again, but I think I'll wait a > while and see who else pops up. I only saw the mention of potentially starting a list in the posting that had a title something like 'RST kit questions and Cozy MKIV...' or something like that. Is that the post you are referring to? Lee p.s. Thanks for your reply about the peel-plying question. This past weekend I cut the wood and put together two halves of the wing jig table. I used 5/8" particle board on tops and 1/2" flake board sheathing on the bottoms. The sides are 1"x8"x6' pine. They are barely light enough for me to move around by myself. I'd like to come up with a way to wheel them around and attach them together in the middle when required. I hate the thought of attaching legs to them at this point because they are just small enough to get out of the basement (without legs) and can easily be stood up on end to get them out of the way. They are 3'x6'x8" each. I've put one of them up on a pair of saw horses but the top is too high (~38") so I'll either have to cut down the saw horses or come up with removable legs. The next item is to section off a part of the basement with 4 mil plastic sheathing to act as a dust barrier. I've been reluctant to do any wood cutting down there so far because the dust ends up everywhere. Then I can do the heated epoxy cabinet, a roll-around cart, the cloth cabinet, and then, finally, I can begin the plane. From: Lee Devlin Subject: Smiling jig table question Date: Mon, 27 Feb 95 10:02:01 MST When I built my jig table, I was careful to select only the straightest 1" x 8" x 72" pine boards I could find. I've constructed the table in two 36" x 72" x 8" box halves, primarily to facilitate moving it out of the basement to the garage when the parts get too big to fit out of the basement. I set the two halves apart (on end) for a few weeks and proceeded assemble them together this weekend. To my horror, I noticed that one of the box structures no longer appeared to be 'eye ball' straight as I was having a difficult time trying to fit it up with its partner. Eventually, I traced the problem to one of the 1" x 8" boards which had begun to 'smile' along the its length and in the 8" x 72" plane. I had an extra 1" x 8" board so I replaced the offending board and then laid it on a flat surface only to find that it had taken on .5" of bow in the middle! That much bow in the middle makes it look a little like the St. Louis Arch. Other 1" x 8" boards that I bought a few weeks ago are also nowhere near as straight as they were when I got them. I'm sure it's related to our < 20% humidity levels around here. My question to the other builders is: How important is it to have a perfectly straight jig table? My concern is that the other boards no longer have the straightness that they did when I bought them and, if this is the reference plane for the wing or fuselage, it may telegraph this waviness into the finished aircraft. Are there additional steps in the building process that take out the imperfections of the jig table or will the parts made on it only be as good as it is? Thanks, Lee Devlin Date: Mon, 27 Feb 95 13:12:36 EST Subject: Smiling jig table question Lee; >My question to the other builders is: How important is it to have a >perfectly straight jig table? My concern is that the other boards no >longer have the straightness that they did when I bought them and, if >this is the reference plane for the wing or fuselage, it may telegraph >this waviness into the finished aircraft. Are there additional steps in >the building process that take out the imperfections of the jig table or >will the parts made on it only be as good as it is? In my experience (both with a Q2 and the Cozy) the jig table is important, but not critically so. I NEVER relied on the table being straight - in any set up, you level, shim and straighten the jigs, check them three times, and then check them just before the layup. As long as they are stiff enough and supported enough not to move in the 12-24 hour cure period (once they're straight and level) you're set. -- Marc J. Zeitlin E-Mail: marcz@an.hp.com Date: Mon, 27 Feb 1995 14:33:11 -0500 From: SidLloyd@aol.com Subject: Re: Smiling jig table question >Are there additional steps in >the building process that take out the imperfections of the jig table or >will the parts made on it only be as good as it is? I made my jig table out of 1" X 12" boards with 3/4" particle board on top. This box structure was built on a frame of 2X4s mounted on rollers but the thing is so heavy it will hardly roll! It is 4' X 16' and I had the same problem you did with sagging. I pulled it apart and added more internal bracing going to a brace every 2 ft. Even that still sagged. Then I found some 1.5" high density particle board. This is what is so heavy. I mounted it right on top of the other particle board and now it is very straight and has remained so for 3 years. Sid Date: Mon, 27 Feb 1995 19:38:08 -0500 From: Ewestland@aol.com Subject: Jigging Here is what I did for my jigging table. I built mine out of (3) 12-foot 2x4s and two sheets of particle board about 1/2" thick. I ripped the particle board down to 24" wide (you might need to make it wider for the fuselage side jigging, I forget, but this width works well for the canard, main spar and wing work) and then glue/nailed the faces to the 2x4 edges with the third 2x4 running down the middle. This table is surprisingly heavy and will sag if only supported on the ends, but I like the sag, because like Marc, I never trust the table. Even if the table was level, my basement floor is not, so once I get it into position to do the work I want, I "string it". Having a flexible table allows you to shim it with mixing sticks until it is just right. Once in place, I bondo the sucker so it won't move when I smack my head on it while bending over to pick up a mixing stick. When I string it, or anything for that matter, I use fishing line. It's easy to see (especially the neon stuff) and stretches really tight. I will also use 3 blocks that are the same thickness, placing one under the line at each end and then using a third block to check distance from the string. This works really well as you do not need to worry about that string "sitting" on a high point. Other jigging tools I wish I had bought the first day include: A 7' or so long piece if extruded aluminum that can be used as a straight edge. A really good 4' level. I tried starting with the one I used to build my house and discovered a nice twist in my fuselage that was lots of fun getting out. Evidently it had been dropped 3 stories once too many times. An electronic smart level which will give you angles within 1/10th of a degree. Torpedo size is fine because you can always place it on top of another level. A good torpedo level is nice as well from time to time. My wife teases me endlessly about the number (4) of levels I have, but they are indispensable. A 2-temp. Black and Decker glue gun. The high temp sticks to anything and the low temp. is good for gluing foam as it won't melt it. I have not used any of that great-smelling 5-minute epoxy since! That's it for now, hope it helps. My students are almost done with their tests, so it's back to work. Eric Date: Mon, 27 Feb 1995 19:58:42 -0500 (EST) From: pathways Subject: Re: Smiling jig table question I ended up putting a second top on my work tables. I made one table 8ft long and the other 4 feet. To ensure everything was straight I put several cross beams from 2x4s and used screws to hold everything in place. Even with all this the table still has a twist about three inches into the table. I marked this off so that when it is important for straight pieces I avoid it. ...Marty Kansky N321CZ, glassing the exterior fuselage From: Lee Devlin Subject: Jig Table revisited... Date: Mon, 10 Apr 95 16:47:07 MDT A while ago I posted a question about my 'smiling' jig table and got some responses which indicated that several of you had similar experiences and generally solved the problems by beefing up the table. My problem was the result of the sides (pine 1x8's) beginning to warp after I built the table. I believe this was partly a result of the wood drying in this dry Colorado climate. One of the boards had formed a 1/2" smile along its 6' length and made that half of the table unsuitable for laying up the bulkheads. I was at the lumber yard last week and was admiring the straightness of the wooden I-beams they've begun using in home construction. The flanges (spar caps) are pieces of joined 2 x 3's glued to a spar web which is 3/8" flake board. You can get them in any length up to 60 feet! I couldn't find a single example of one that was warped or twisted. So I bought 6 of them and proceeded to dismantle my jig table (which is in two 6' halves) and reassemble it using four 6' x 9.5" I-beams as table sides. I cut up the extras up in 2' lenghts and used them in 5 places cross-wise to prevent sagging of the table from side to side. It made an amazing difference. The table looks 'eye-ball' straight down its entire length. Walking along the table feels more rigid than walking on a floor in the house. I use 4 saw horses to support the table, as the joint in the middle is only for alignment. I can still (barely) lift each half of the table when disassembled to move them around. There are several other advantages to using the I-Beams as table sides. The wide flanges make it easy to screw into them. They also make it easy to grab the table to lift or move it and will allow you to clamp things to it. Incidentally, I've been using drywall screws for the past several years for this type of assembly and find them to be cheaper, stronger, and much more convenient than nails. They also countersink themselves and are easy to remove. I suspect many of you are doing the same. The I-Beams are about twice as heavy as the boards they replace, but only add about 20% more weight to the table overall, thanks to the significant weight contribution by the particle board top. The I-beams are more than 5 times as stiff as the 1 x 8's. Because they are made up of a lot of small pieces with little or no internal stresses, there's no tendency to warp. You can get these I-beams at most lumber yards for around $1.60 per lineal foot. You won't have to sort for good ones either since they are all straight and true. They come in 9.5" and 11.5" heights. Hope this helps. Lee Devlin Date: Sun, 16 Apr 1995 22:30:22 -0400 (EDT) From: pathways Subject: Re: Mailing list update Marc, For creating templates my friend Steve Sharp used formica (spelled correctly). They are really stiff and the wire had no effect on them. ...Marty