Hatz Biplane Association

Where the tail spars meet the tubing of the leading and trailing edges, you run into the issue of mating different sized tubing. Typically the solution is to heat and taper the larger tube so it matches the smaller tube.

All good except when you flatten or taper the larger tubing it spreads out. Thinner in one dimension, wider in the other. This causes the gap between surfaces to be uneven, smaller at the tips.

The question is how to flatten a tube and have it all spread to only one side?

The answer is to slightly bend the end of the tube before you flatten it, that way when it spreads, it goes back to straight on one side.

Mark

It is sometimes surprising how much joy one can find in a simple accomplishment such as a bending of a 3/8" tube. And even more, when one manages to get two pieces of tube bent similarly.

Here is my achievement of the day: Two similar-enough trailing edges for the elevators.
[attachment=1]trailing edges1.JPG[/attachment]
[attachment=0]trailing edges2.JPG[/attachment]

I used a combination of the wood quarter-pie bending apparatus that I made with a 8" radius (still not quite small enough as there is considerable spring-back) and the hand pipe-bender.

While I continue on making the rest of the parts for the elevators, I am looking for close-up pictures of how builders welded the outboard tips of the elevators, where the trailing edge meets the spar.

Its a beautiful thing...

And here they are, the two halves of the HS:
[attachment=0]20150202_182452.jpg[/attachment]
My bench is getting lighter and lighter with all these holes...

Thanks for the replies.
I found a place to sheer the sheet metal and bend my channels. It is good to have friends with machines...
[attachment=0]Bent.JPG[/attachment]
While the bent channels are very rigid compared to the flimsy strips of metal, one can still straighten them with moderate force to the point where they lay perfectly flat.

I was fortunate to find a co-worker with an old Pexto Seaming break. Check local HVAC shops. They might have one or know of one. They may be able to fabricate what you need. I bought some U-channel from a local garage that builds custom hot rods. The owner said he has a batch made up periodically and sold me a few pieces.

Sheet metal brake.
I've also seen where people make the channel in two pieces.
Two 90 degree "Ls" - one on the top and one on the bottom with tack welds several places along the meeting line.

Jeff Moore

Hi All,
I am looking for tips on how other fabricated the metal channels, for example the ones used as "ribs" on the the horizontal stabilizer.
These are bent out of strips of 0.025" sheet.
How did you accomplish the bends?