Bending round tubing smoothly is a relatively simple process and there are a lot of machines and tools that will do those bends in your garage. But bending square or rectangular tubing is a completely different animal. Unfortunately, bending square and rectangular tubing like you would use for frame rails, results in wrinkled sides if you don’t use a mandrel bender. A mandrel bender inserts a mandrel, which is a die that fits the inside of the tubing snuggly, so that it sits inside the tube at the bend. It must move with the tubing and keep the sides from collapsing. It’s cool as hell, but a machine that most folks are not going to have in their home shops.

Here’s how it works at Cornfield Customs.

Video Description:

Full walk through of the cutting, lay out, machine operations, and bending of 2 x 4 x .188 steel rectangle tube. Bending up some custom hot rod frame rails for the walk through.