ThunderCactus,
I think your diagnosis is right about the broken metal tooth on the piston. I was using a bearing spring guide. See the three attached photos. In these pictures, I am using the piston that came with the J.G. mechbox. The spacing on that last metal tooth is about 0.3 mm wider than on the Aftermath piston (which I had stripped and broken the metal tooth).
First photo: Shows the bearing spring guide and piston in the starting position.
Second photo: The piston has moved to almost line up with the bearing on the spring guide. Even when I cycle it by hand, the piston sometimes hits the bearing.
Third photo: The piston is all the way back, just about to be released. However, it doesn't seem to make contact with the back of the mechbox.
I also tried your second suggestion - pistons jamming on mechbox window/piston rails near back of mechbox. I re-assembled without the spring and spring guide and verified that the piston could slide smoothly to the back of the mechbox.
So, I guess the broken teeth was caused by the piston striking the front edge of the bearing on the spring guide. If so, why are bearing piston guides used/sold?
Quote:
Originally Posted by ThunderCactus
That metal tooth broke, to me that indicates the piston is hitting the back of the mechbox, or seizing, while the sector gear is still engaged.
Do what you did before, cycle the gun by hand through it's motion, but remove the spring and leave the spring guide and piston in there. See if the piston hits the spring guide.
If it's a bearing spring guide, the back of the piston MAY be jamming on the bearings.
I've seen pistons get jammed on mechbox windows as well, the piston rails near the back of the mechbox may be poorly cast and causing the piston to seize up.
How you can test for that, is by assembling your mechbox without the spring guide or spring, and pushing the piston to the back of the mechbox with an allen key through the air nozzle. Ideally, gravity should be enough force to have the piston fall forward.
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