I started off with the 3" barrel for Colt model, but after I thought I had the gear figured out I increased the length to add power/force to shots. That is when the draftboard started falling apart, being smashed to bits by the force.
So I started dipping/soaking the gear and escapement in UV resin. This added strength and little longevity to the pieces, but they still wear out fast if I try to use more than four bands. (It is designed for six.)
Unless I try to cut the pieces from Delrin, I am not sure I can take it much further. I think I have taken the Draftboard to farthest point it can go in this project.
I did, and two of the gear teeth snapped after the first shots. Now that was earlier design and the gear design is “sturdier” now, but I am hesitant to try again do to how catastrophic the last attempt with acrylic was. The draftboard slowly breaks down, but the acrylic does not appear to handle the impact very well. It doesn’t get smashed and start to fall apart, it just cracks and breaks off.
I went ahead and soaked the gear in some of the UV resin (just for added strength). And while it was drying I put the Colt together with a couple of the old draftboard gears, just for some more testing while I waited.
It shot 6 bands pretty easily. So I kept going just to see if it would start to wear down. After 7-8 reloads, I started to notice parts of the old gears flaking off again, but the escapement showed no sign of wear at all.
Once the new gear (two plywood gears glued together) dried from the resin dip, I replaced the old gears and continued testing.
I started to wonder how many bands can I fit on here? I got it up to 9 before they started binding with one another, but they still all fired. And still no wear showing on the plywood. Plywood definitely seems the way to go, and doubling the inside layer helping spread out the impact also.
I did not use the UV resin on the gear this time. I wanted to see if it could hold up to the impact with it, and it has not been having any problems so far (even though I keep loading it with more bands than it is designed for!)