*UPDATE 8/13/08* Pnuematic Shank

[Lentamentalisk]

First of all, some sort of bumper is needed to keep the bolt from destroying the entire contraption. The spring return could help (though it would slow its acceleration the entire way...) also, a rubber bumper could help. To lessen the impact against the casing, you could drill vent holes near the very end, just before the bolt reaches the end of its cycle. This would also ease in the returning of the bolt.

[blind909]

Here is a picture of my piston:

[Lentamentalisk]

I really suggest a QEV or something of the likes. I know you are trying to get it to run off of a tank, but you could but a valve or something on the line. A QEV would really up your flow, (at least from the 1/4 ball valve) and wold open a bit faster.

[blind909]

The performance is fine for me how it is, And I wil get a video up soon. It opens extremely fast, and it can already punch through 1/2 inch plywood, so its fine. And I dont have the money for a QEV.

[blind909]

This has been taken apart for now. I need to get some metal pipe instead of the pvc, as the pvc is cracking from the force, and It will all be threaded, and I will also get some bondo.