Bending the T-406B Fuel Cap Flange

[Mouser]

I'm basically done with the initial assembly of my first fuel tank except for bending the fuel cap flange to be flush with the skin. Can anyone share their technique for bending the (very thick) flanges?

The way mine came, the flange droops down on two sides, but those two sides aren't opposite each other, so it just looks sorta melted and is a long way from flush. So I think they need a fair amount of work. What's the best practice for reshaping these?

[flion]

I haven't done the flanges for the -10 yet (just about to later this week), but here is what I did for the -6A: I took a couple of drill bits and placed them under opposite sides of the flange with the flange facing down. I put a block of wood on the inner flange and used the 'big hammer' technique (5 pound sledge) until the flange rested on the surface with the opposing edges up on the drill bits. The bits left a slight mark on the face of the flange which polished out easily on the deburring wheel; the thickness of the flange means you can polish aggressively if you need to and not lose strength there. I suppose the right way to do it would be to machine a form block but a couple of 3/64" drill bits are a pretty cheap substitute.

Edit: I assembled the tank today, so I took the time to check out the filler. Mine was over-bent, so my advice was no good. You'd actually have to lessen the amount of bend to get a good fit. That's with the pre-curved flanges I got from Van's almost two years ago. Also, I too was unimpressed with how the fore and aft bends were not aligned symmetrically with each other. I'm going to mark fore/aft points and put the thing in a vice and see if I can't carefully unbend and align them at the same time; I'll report back in a day or so and let you know how it came out.

[flion]

Well, I had some time to kill today, so I attacked the filler flange task. How I Fitted the Filler Flange - it was easier to write this up on my wiki than try to do it on the fly here. I hope this helps.

[Mouser]

That's very helpful indeed! Thanks Patrick.

Originally Posted by flion

Well, I had some time to kill today, so I attacked the filler flange task. How I Fitted the Filler Flange - it was easier to write this up on my wiki than try to do it on the fly here. I hope this helps.

[paul330]

You might want to consider the lockable fuel caps. Expensive but beautifully made. The flange is not bent but machined to fit the curve of the skin