I mentioned briefly when I started phase 2 that I’ve been considering many different methods of attaching the stock to cannon. There are definitely simpler solutions than this clamping arrangement, but at the time I was making the decision I’d already worked the whole thing out in cad, so might as well do it that way I guess. I went through a LOT of extra trouble to avoid using hose clamps or any other bands with tensioners. The up side is that it should look really nice and be easy to disassemble.
Anyway, enough talk here’s the design:
The arrangement consists of a 1.5×1.5″ 1/8″ wall U-channel that’s attached to the cannon body with 3 stainless steel bands (red). Each band is attached to an aluminum block with machine screws. The bands will be able to slid around ..for now. If you look carefully there are holes on the bottoms of the blocks as well, bolts will go through those holes in the U-Channel and thread into the blocks. The idea is that when you tighten the bolt it pulls the u channel firmly onto the cannon body, and at the same time tensions the bands so they can’t slide.
Q-Loaders use a similar system to mount onto a paintball marker. I had one and was surprised at how sturdy the connection was, that’s what gave me the idea.
Lets get started.
I started by drilling the holes in the u and making the blocks. All the pieces are square and easy to fixture so it went really fast.
I cut the blocks from a 6″ piece of 3/4″ square bar, I then milled off the bandsaw’d area to make them a little square-er and prettier, that wasn’t even really necessary though. After that it was just clamping, drilling and tapping to finish them up.
Next I started making the bands. I only needed 5ft of the banding, but the least I could buy was 25 so I had plenty to spare. The bands cut nicely with sheet metal sheers. I made the holes with a sheet metal punch.
The hard part about the bands turned out be getting them to just the right length. I’m glad I had extra.
These are 2 of my rejects. The top one is too short, and the bottom one is too long, it has to be pretty precise. I made the rest of the bands about half way between these 2 and they fit nicely.
Here’s one of the bands assembled. If you look carefully, this is actually one of the too-short ones.
Here’s one of the finished ones after I got the band length dialed in.
I threw the u channel in the mill real quick and milled out some space for the bands.
Time to check the fit. Looks good. I proceeded to tighten the whole thing down.
Conclusion: It looks nice and feels very sturdy. I might eventually put some cross braces in the u channel just so the legs wont push apart if you really crank down the bolts, but I’m not too worried about it for now. I’m really happy with how nice this turned out.