They make dies. There is alot of engineering data there on that site you will find useful. They make dies there that will bend 8" diameter tube in a 16" centerline radius so I'm sure that the 3 1/2 " tubing you want to bend will be a cinch. They build dies from 1' on up so you can get all of your dies there. Hope this helps, mikey
my signature lines...not really directed at anyone in particular..
BE different....ACT normal.
No one is completely useless..They can always be used as a bad example