Cross Bow II

Description

Similar design to Cross Bow I with the primary difference being (metal) spring powered instead of rubber bands. I would link to keep this model as small as possible, possibly handheld instead of rifle sized. That would mean 18" or less, so the bow arms would need to be 1/4 of that or 4.5 inches. The springs are attached to the bow arms 2.5 inches from the center of rotation meaning 55% force (with a corresponding increase in distance) or a draw force of about 88lbs. I will need to put a sirup on it (rope should do just fine). I also want a cocking handle, that should help.

Trigger

I plan on using a similar trigger mechanism as in Cross Bow I but instead of a single string catch, I want two smaller catches spaced wide enough apart that I can knock a bolt between them.

Bolt

Again, similar to Cross bow I, I want to use a slightly smaller size dowel rod, (1/4 to 1/2 inch). The bolt will have two sections glued together with a fin. The main body of the bolt will simply be dowel rod a few inches long (sized to fit the cross bow) with a rounded front and the back slit to fit the fins.

The fins are cut from a pop bottle and are angled to cause the bolt to spin in flight. Past experience says paint the fins orange so they are easy to find.

The knock is a small piece glued on the end so the string doesn't split the bolt along the split cut for the fins. This is where I want to get a little more complex. The previous knock design was simply a groove for the string. This time I want to drill a small hole 1/4 from the back end of the knock. Cut a small opening from the back to the hole, with tapered sides. The objective is that the tapered edges will guide the string into the hole but once it's in, the opening will be small enough to prevent the bolt from falling off easily but still allow a smooth release when firing.