Big-E wrote:I used a 3/4" machine screw anchor, it's a two piece steel fitting that is crushed together when you a machine screw in it, and it presses into whatever the screw is going into. I sealed it up with JB Weld Epoxy, and threaded it onto my rod. once cured, I used a dremel, a couple of files, and sandpaper to make the grooves for the o-ring and air relief notches.
The o-rings I used were:
5/8" I.D. (13/16" O.D.) x 3/32" wall for the piston
1/4" I.D. (3/8" O.D.) x 1/16" wall for the check valve.
I used thicker, L Rated 3/4" tubing for the pump body.
I think I may cast my piston entirely from epoxy and for the grooves what bit did you use