rmich732 wrote:The 2"x3/4" galvanized bushing is nice, because it distributes some of the weight of the gun to the back (making it easier to hold), as well as prevents an explosion of the back end. However, now the female adapter is the most likely to fail... oh well, better than the plug!
I wrote this on spudtech on November 7th, 2006... Seeing into the future perhaps?
So I basically am sure that the combination of tightening the bushing too much, using a metal bushing, having a less than sufficient bumper, and the use of a very heavy piston caused this to happen.
In my new version of this, I will use a SCH 40 plug sealed with an oring and secured by a few screws. The pilot valve will only be 1/4", because if I used a 3/4" pilot valve, the nipple which would screw into the back of the SCH 40 plug would extend too far and not give the piston enough room.
I am not sure what type of piston to use. Sure, 1.25" fittings piston would be lighter, but I was really happy with this one (until yesterday...). As of now, I plan to use the same piston, cut down a bunch (because the valve will be overall shorter), and hollowed out. This will be a tiny bit heavier than the 1.25" fittings piston, but will be much stronger too.
I could post pictures of the bumper, but it wouldn't matter. The bumper was in the metal bushing, and did not extend out of it. The piston only came in contact with the edges of the metal bushing, and therefore the whole assembly was useless (it did cut down a bit on pilot space though...
jjrrw: I thought all fittings had a taper (they are all called NPT fittings, which stands for National Pipe Taper)...