Another issue, with the cannon has been the slow fill time. Even when connected straight to the 150psi shop air line, it takes about 15 seconds for air to stop hissing through the check valve in the piston back (you can hear it). The check valve I made simply wasn’t moving enough air.

I made a couple of changes to improve the flow rate. First I drilled smaller hole out until it was only barely smaller than the ball. I also removed the spring, which wasn’t necessary.

At this point I realized the ball would definitely plug the hole in the retainer plate. To Fix this, I replaced the plate with an S shape piece of aluminium tig rod. If this works, I’ll make a nicer version at some point.

Trigger Guard!

I’ve been shooting the cannon a lot lately, and the lack of a trigger guard is starting to be a little worrisome. While I was working on some other stuff at the shop I bent one out of some aluminium scrap. I did it first with some thin flexible metal, then copied the design with pliers and a thicker more ridged strip.

I tapped bolted onto the trigger mounting block and the stock. I didn’t measure the hole position on front, I drilled a hole in the trigger guard first, then just flexed the guard until it looked right and then marked the point on the receiver with a sharpie. When I clamped it in the mill, I adjusted the hole to be centered on the receiver, but kept the x position from my mark.