That was my best uneducated guess but all I’m getting from shops that roll tubing every day is that it can’t be done with thin wall. I don’t doubt you for a second but it sounds like I’ll have to learn enough about it to be able to do it’s myself if need be.Tube bender or tube roller. Weld on a pre made slip fit on the end. Make it all from 321 stainless.
You’re right, each bend was originally made of two stampings edge welded together. I had assumed the modern one-off way was to roll the bends into a tube but I’ve also put a bit of thought into how I could hydroform those stampings if that’s what it came to.I have a vague feeling the bends were welded up from 2 stamped parts, have any of the other Gipsy Moth rebuilders made them recently?
Not based on the drawing in the 1st post. It might not even be needed with a proper bending mandrel. Years ago we had to do some large radome cable bends. Huge coax. Had to design and build a bender that had an inside spool piece and an outside sort of channel both to the right side. Then all you had to do was run a bearing at the right radius off of the capstan center to the outside of the channel piece and run it around. It held the entire diameter tightly and so kept the buckling from starting. We could get much tighter bends without collapse that way.Sand method will collapse or tear...take your pick.
Normally I’d be on board with that, but the end result in this particular case is very visible.And the last and most common DIY method is to just buy a kit of exhaust parts from any of several suppliers. A few hundred bucks and you have enough 45 with straight on both ends. 90's with the same, 180 bends, plus straight, etc... to make any exhaust shape. You have to simplify your centerline path on your drawing to use the radius you get in the kit and you start cutting and tack welding until the ends and middle meet the specification and clear all the obstacles.
It’s 2.25” diameter which it turns out is a bit of an odd size and the bend radius is 16” which is an enormous curve by exhaust shop standards, or at least so I’ve found so far.I can't read the dimensions on the print