SonexBuilders.net

Trying to bend the 3/4" flange on the upper firewall. Can't. Tried to make a form and roll the edge over, NOPE!

Can't find a solution for this.

I assume you are scratch building. My kit part had a ton of flutes. Not all were perfectly positioned. If I were scratch building I would put grooves on the edge of my form blocks and use a thick round screwdriver handle to shrink the flange into the grooves. That was how I made my hummelbird ribs. Somewhere I have a picture. If I can find it I will post it. You start tapping down and the flange goes crazy. Then you tap in some flutes and it gets tamer. I always finish with fluting pliers.

When you say "upper firewall", I assume you are talking about the firewall piece with the hole for the filler neck and the windshield/cowl attachment.

I scratch-built my fuselage but ended up buying all the firewall pieces from Sonex (it was actually cheaper than buying the minimum required raw stainless steel). The big curved flange on top came bent from Sonex. I just had to reposition some of the flutes. If I scratch built this piece, I probably would have sandwitched the piece between two form blocks and pounded the flange down.

Are you actually talking about the rectangular lower firewall? Jeff Shultz's site shows how he did the flanges on that:
http://www.sonex604.com/firewall.html

If I was scratch building:
http://www.titaniumjoe.com
Some of my former Sikorsky coworkers were disappointed that I didn't sell the stainless and buy ti.

Thanks guys. It's the stainless piece with the filler box on it F17-03

I am scratch building. I tried the sandwich route, whacked it with a mallet and it bounced off. LOL. Tried a hammer and it too bounced off leaving a nice scratch. Think I'll have to buy it. Was so looking forward to be ing it so I can assemble the forward fuse. Thought about fluting and bending with a pair of pliers but that would just make a mess.

Oh well.

Are you sure you've got the correct stainless steel grade/thickness?
I do not remember having any issues bending the flange over the form block with a mallet:
http://www.mykitlog.com/users/display_l ... 50&row=109

It was almost as easy to bend/cut as aluminium, drilling on the other hand....

I agree with Michael. It is easy to bend. My kid bent mine up for me.

SNX1542 wrote:I tried the sandwich route, whacked it with a mallet and it bounced off.

I scratch built mine and this was what I observed at first as well. You just have to use quite a bit more force than you did w/ aluminum (hit it really hard) and it will form a nice edge...mine came out great. It was a bit more challenging to do the flange for filler neck section...for that, hitting over a form block didn't work for me, I just used some seaming pliers and bent it over a little at a time.

I'm sure it's correct. You'd be surprised how difficult the SS is to bend at .016 HH. Seems flimsy but its not. Today, I'll try to work it over then. Hitting it in the form won't do a thing except chip apart the mallet. I'll grind down the face of a pair of plyers and use those as a seaming tool. Give it a go, nothing to lose, it's been done before and no reason I can't do it :D

Just wanted to follow-up on bending F-17-3 Upper firewall. Form bending like the ribs won't work, or at least didn't for me. I suggest grinding down flats on a pair of vice grips. Then folding over the stainless till it deflect, the flats will prevent marking up the shiny metal to a great extent. Then fluting, and some more bending. Worked like a charm! Thanks all for the motivation to do it myself.