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Building Tips and technical articles. => Building techniques => Topic started by: Leester on January 02, 2011, 12:45:31 PM
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This was over on SSW so I thought I'd bring it here.
http://home.mchsi.com/~howard.sullivan/ConstGuide/FJConstr.html
I decided to build one as it seems pretty straight forward and easy enough to build. The list of materials to buy came to less than 20.00, most purchased at Menards with the bolts,washers and wing nuts at True Value. I substituted particle board for 3/4" ply base as it was pre cut at 11 1/4" X 48" for a couple of bucks. The 1/8" hardboard was 3.00 for a 2' X 4' piece (would fit in the car) and a 1/4" X 4" X 48" piece of pine ? was about 4.00. I had the white paint,glue and sharpie, also had some MinWax clear poly and figured I'd clear coat it after it was done (mistake !!) it made the lines I put down with the Sharpie bleed. I have a table saw, miter saw and a drill press which made things alot easier but you can do it with a circular saw and hand drill and a steady hand. I'll use it on my next project, I should have all the side clamps glued up this afternoon and the poly should be dried by then also to show a finished shot.
This is a quick jig to make and should last awhile.
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More pics
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HI Lee. That is very simlilar to mine, which used ready sized shelving, not unlike yours. One thing I did , just in case, was to screw two one by two lengths to the underside to prevent any warping. Seems boards like to warp from weight if not humidity. FWIW. H^^
Hi Ty,
Not that it means anything, but if you could get some 3/4" square steel tubing, locally, a frame made of that bolted to the bottom, will insure that it stays straight. A welder (if you cannot weld at home) should be able to quickly and cheaply square it up and weld it.
We happen to have a metal shop/blacksmith locally. it's pretty cheap to have done, and you know if I say it's cheap, it is. LL~ it will also help with your level of physical activity! LOL!!
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Thanks for the tips guys. Well it's all finished but it looks like I have to make another trip to the hardware store, two of the wing nuts are stripped or something as a half turn and there to tight to move .
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I think the good thing about the chipboard shelves is that they will tend to conform to the surface they are sitting on....your workbench. If your workbench is flat and straight, the fuselage flexi-jig will be fine. If you want to lay it on your lap and build while you're watching football, you need to do something else.
As a machinist by trade, I'm pretty horrified by y'alls assumptions that metal tubing, bar, plate, and angle are straight and square. Trust me, they are NOT! If you look up the standards for that sort of product, they will tell you how close they are required to be. Usually, about .030". If I machine them, they'll be closer, but still not perfect. That's why we have tolerances on drawings. I had a small plate to machine last week. Dimensions were on the PL, and the PL said .1875" thick. Because of that being on the PL and not on the drawing itself, I can only guess what the tolerance is, and the result is that I just make it as close as I can. It came out -.0005" to +.001", and I was happy with that. I'm sure it's good enough, but it's still not perfect. It was Delrin, OBTW. Boeing tooling...hate it! Still, it pays the bills pretty much... n~ Steve
PS: Leester...surely you have a 1/4-20 tap to run through those defective wingnuts?
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Nope I don't.
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Hi Steve,
I am not horrified by what I said (and being the only one to say "Square steel tubing", use my name, y'alls is plural). Never will be. If I were building a Space Shuttle where several lives could be dependent on .030, I would be MORTIFIED. ;D There is no "absolutely perfectly flat building board" in existence in a model builder's shop. If there is, it is purely by accident. Very, very, close to flat, but not perfectly flat. And until we have better technology that can be used by those of lesser means than Donald Trump, there never will be.
A good blacksmith/welder can make a frame out of 3/4" steel tubing that will keep a fuselage jig's wood components from warping. That was the reasoning behind my comment. A steel frame will resist the board's warping infinitely better than wood strips will. And cost way less than any exotic wood that might come close. And will be AT LEAST the equal as far as straight and true, probably better over the long run, since the steel doesn't posses the same traits that will cause wood to warp.
If we need something better, we had best come up with a tool/device that will allow us to use an invisible line on our plans. Think of how far off things get from the spinner ring to the tail post on a 42" fuselage when subjected to making parts from line drawings. Laser cut parts are much more accurate, but only as good when built as the ability the builder has to assemble them.
I don't make wild A$$ assumptions. I do state facts based on personal experience, though. And welding a frame that will be much more than suitable is an easy job for a "welder". There are plenty of people out there who weld, but a "welder" is n a different class. If they can't do that job to close enough specs for us to build a toy airplane, they should have their welding units destroyed, they ain't "welders".
Now, how about I say what I really think? LL~ LL~ LL~
If this offends, you need a skin graft.
LL~ LL~ LL~
Big Bear
(Home address available on request ;D )
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Thanks for the tips guys. Well it's all finished but it looks like I have to make another trip to the hardware store, two of the wing nuts are stripped or something as a half turn and there to tight to move .
Leester,
Looks good. I built myself one a few years ago, and built another for my brother in law for his birthday. I had the verticle pieces made by a customer of mine who owns a cabinet shop (I think he charged me about $20 for all of them).
Whats the profile setting on the bench in the picture?
James
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Thanks James, it's a Bucaneer 746 P
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I use the menards shelving for a wing jig. It is clamped to a bench. The plans are taped on it, covered in wax paper. Then I use 90 degree braces screwed into the board as rib locators. Clothespins hold the ribs vertical. this works great for building flat on the surface. The one thing everyone has to remember wood is a moving thing. You can't force it (clamp) and expect it not to respond after you take it out. Don't be shy about replacing kit wood if you think it is bowed or warped. yes you can get rid of some of the warping during finishing, but when the weather conditions are right it will warp again.
The Brodak Sea Hurricane I'm building now is the 1st with the TE elevated. The jury is still out on this, I'm not sure I'll go this route on the next one.I need to build an adjustable TE support for this .The reason I jig this way is to avoid using pins. i have an inherited tremor that gets worse as the work gets more tedious. My fingers become pincushions after a wing half.
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Steve, if you have problems with using pins you might consider using the rod jig method. You'll have to put jig holes in the ribs and line them up correctly but thats how I do scratch built up wings. To get a straight wing extra work is worth the effort IMHO.
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I finally took a picture of the jig I have. Byron Barker at C.F. Slattery. Probably a one mega ton nuclear device wouldn't harm it! I finally bit the bullet and bought one. Ecstatic that I did!
Big Bear
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Your right Bill, it looks BOMB proof. lol
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Your right Bill, it looks BOMB proof. lol
Hi Lee,
The deck is machined aluminum 1/4" thick and a centerline scribed, the uprights are about 3/8th" thick machined aluminum, the supporting frame is 3/4" steel tubing, welded and bolted to the deck, and the set screws have about a 3/8th" diameter shank. It is "substantial"! (and I don't have to worry about how I "store it"! LOL!! )
Big Bear
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It looks like a pretty nice one but I only want the 90 degree clips. I dont have room for the plate.
John
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John, Talk to Jim Snelson at Control Line Central.
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I second that. I got some nice ones from CLC.
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Jim's CLC jig is excellent. y1
Big Bear
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I guess that you all know that that fuse jig was a construction article in Radio Control Modeler. It was published in the late 60's or very early 70's and was an immediate hit. I've had one for years but gave it away to save space. I borrow my old friends jig when I need it.great ideas really do endure.
Dennis
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Don't know if this is needed or not but after finish sanding all the edges I added this adhesive foam strips to protect the fuselage sides. Unfortunatley Menards didn't have it in 1/2" wide so I had to settle for the 1/4". It was less than 2.00 a bag so not a big investment.
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Big Bear...Frequently, folks make posts about using "angle iron" or "aluminum bar" or some other sort of metal "to ensure that (something) is square or straight". Off the rack, it's generally not very straight, flat, or square. Just the way it is. Everything has tolerances, and it's cheaper to make the looser the tolerances. That's all I'm saying. If you got a good result, great. It doesn't mean that anybody else will be that lucky.
I've worked with some welders that were truely talented folks. I've also worked with some that left a lot to be desired. Same for machinists. Mostly, they fail to see the problems ahead, and don't plan for them. In most cases, "using the tolerances" will just make things harder at some point in the future, if not impossible. For myself, often I'll clock out and head for the door thinking "fooled 'em again!". It's hard work to dazzle them with brilliance, when they conspire to stack the deck against it so completely and consistently... H^^ Steve
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Big Bear...Frequently, folks make posts about using "angle iron" or "aluminum bar" or some other sort of metal "to ensure that (something) is square or straight". Off the rack, it's generally not very straight, flat, or square. Just the way it is. Everything has tolerances, and it's cheaper to make the looser the tolerances. That's all I'm saying. If you got a good result, great. It doesn't mean that anybody else will be that lucky.
I've worked with some welders that were truely talented folks. I've also worked with some that left a lot to be desired. Same for machinists. Mostly, they fail to see the problems ahead, and don't plan for them. In most cases, "using the tolerances" will just make things harder at some point in the future, if not impossible. For myself, often I'll clock out and head for the door thinking "fooled 'em again!". It's hard work to dazzle them with brilliance, when they conspire to stack the deck against it so completely and consistently... H^^ Steve
Hi Steve,
I didn't mean to "argue". ;D There are folks in all walks of life who can do things "right" and others who "think" they do things "right". The closest tolerances I ever have had to deal with (even now) are in the .0001 range, and that's not possible with our "toy airplanes". ;D
In building model airplanes, a pencil line is more than what 99.9% of the human beings who do this can aspire to, as far as accuracy goes. Knowing Ty real well, I know that as an old NAVY Chief, he can tell if it's good enough. ;D I would hope others could to! LL~
It's easy enough to get the surface of the jig like I have "flat" in all directions within a "sheet of typing paper". The use of the steel tubing was to keep it from distorting "later", and is jig made, not to "make it straight" to start with. Closer than that isn't a necessity. Dealing with balsa, a "live" product, assures that.......... ;D
Thanks!
Big Bear