That's sort of like hydroforming without a dye.

 

Yeah- that's where I've been headed- "Ok then, can I build a mandrel bender?".

I have been looking at taking a similar approach to what guys do building regular benders- buy some tooling, build the rest.

So basically pick a rotary draw machine with a design that lends itself well to adding a mandrel- no huge deal I don't think.

The mandrel is easy enough- but the wiper die is a pretty sophisticated piece.

I will probably build it with the thought that I may need to retrofit a wiper die, but just try a mandrel at first.

Some mandrel benders "boost" the material around the die, things can get complicated fast, but my thought is that if a guy just built a more deluxe version of a standard bender and kept evolving it, he might be ale to get something decent.

I am thinking I will likely go to 14 gauge (0.083") material for the headers as a nice compromise between 16 gauge and schedule 10- one benefit is that it should be slightly more forgiving when bending.If I can come up with a way to bend 1-5/8" x 0.083" stainless on even a 3" radius (6" between the legs on a u-bend) I will be in great shape.


I am thinking about basing it on this bender:

http://www.mittlerbros.com/tube_bend..._hydraulic.htm

They have extremely detailed assembly drawings for it on their site, along with parts lists.

I'd likely buy the gear/rack assembly and maybe the shaft from them, and a 1-5/8" die set. Then I'd have a smaller radius 1-5/8" bend die made (my brother is a machinist, yay!) and set up a mandrel.

It's basically just a 4'x4' welding table with a 3/4" thick steel top with drilled tapped holes for the tooling, bracketry for the hydraulic cylinder below, and that's it.

Famous last words...

 

i need 2.5 bender

 

does this work?

 

somebody called?