Million Dollar Skunksworks Kirkham

David Kirkham · #1 (**permalink**) 07-06-2008, 09:59 PM

This is a different view of the bender. The rollers at the top (the machine is not entirely set up at this point so it is hard to see) are 3 rolls. One of them is movable (on the bending arm) and so it will move at a certain angle and the tube is then pushed against that angle to make a large radius bend in a tube. It is really quite cool to watch it in action. I will post more pics and maybe even a video when it is all together so you can see how it all works.

The bronze color shaft with a groove in it is actually the axle the bending dies sit on. Well, we needed a smaller radius than the machine could handle, so we just made a new axle with a groove in it. The hood, trunk, and doors, have a very tight radius in them that require the special tool we made.

David Kirkham · #2 (**permalink**) 07-06-2008, 10:03 PM

Here is a pic of the collet we made for the push bending. We made the collet from 17-4 PH H900 material. It is the same material we make our hubs and axles from. It is ridiculously strong. I love the stuff because it is a PH or precipitation hardening material. PH means that in order to harden the material, I only need to heat it up to 900 degrees. Other materials, like chromoly have to be heated up to 1525 F and then quenched to get hard. The quenching process is hell on the material. Any stress raisers will cause the material to crack from the quenching shock. 17-4 is really expensive (about 5 times more expensive than chromoly) but you don't have to worry about losing a part in heat treat from a stress crack so it is worth it to us. Not to mention, 17-4 eliminates micro cracks which scare me to death. Some things are just better to use the good stuff on. There are better materials, of course, but cost becomes prohibitive.

In the previous picture, it is a little hard to tell, but you can see the 2 inch collet in the end of the push ram. It has the mandrel sticking through it. It is the piece with all the little holes in it that is cut into 4 segments. I cut this collet apart in the next pictures.