My version of stringer bender -worked for me

[John Bickham]

I've seen a couple of suggestions for putting bends in the 1" x 5/16" stringer material that Mark uses in his kits. I've seen suggestions from pretty elaborate, machined jigs to Marks 4x4 on the floor and hop on it method. Both are great and work. This is just a suggestion for another way to do it. After my trip last week to see Ron B's 4 place kit and Bill's newly acquired partially completed Patrol kit, I saw what was possible in bending the stringers.

I had some 5/16" aluminum scraps and made a little jig to bend using my work table to hold the jig and maintain everything in a straight plane with not deforming.

This is what I came up with and it worked pretty good on a short piece used as a pattern. And then I was able to repeat the bend on the actual length. Doesn't take a lot of pressure or force to bend this stuff. Trick is consistent duplication of bends for consistency and maintaining a straight bend without bulging of material.

stringer bender (3).JPG
I had 5/16" carriage bolts on hand. 3/8" might be better. Aluminum is easy to cut and sand smooth. Some hard oak may work with more material to bolt to.

stringer bender (1).JPG
Mounted to side of work table. C-Clamp helps with the pressure put on the jig during bending. A flush sided work table is kinda a requirement for this to work. stringer bender (2).JPG
Pattern bent. This was a 3 foot piece, so I felt confident I could repeat on long piece. I marked the stringer in 2" increments. If you look on the side of the table, you may make out the bend points for the different locations.
pilot side top stringer (4).JPG
And there is the final result. On the first try (after pattern).

Hope this is helpful. Thanks to all those previous suggestions that helped me accomplish this "not as hard as I thought" step.

[alaskabearhawk]

great minds think alike..

http://www.mykitlog.com/users/displa...g=217910&row=3

[John Bickham]

Not so much Paul. Your technique was one of the sources for my approach. I'm glad to see you have gotten back in the shop. I do better with you in the lead and me following. ;<).....

I refer to your kitlog site on a routine basis and it has been a huge resource.

Thanks too much, John B

[sjt]

John Bickham, we met at Mark's place last year. I was wondering if you use anything (oil maybe?) when you seal up your fuselage tubing.

sjt
Stan timmerman
Austin Tx

[John Bickham]

Stan,
It is on my list toward the end of all the welding, tabs included. Heat of welding with linseed oil inside will aggravate holes being blown out in a sealed up tube. Even more vapor pressure. Probably not a issue in long runs but with my luck it will happen on some short piece that I heated up too long. I even read some article about heating tubing with linseed oil in it and basically smoking your tubing from one end to the other. I guess the tube oil is still mostly linseed oil. Anyway, on my list once I've finished 99% of the welding at least.

john b