The main issue was dealing with the barrel. On my bow, the barrel sticks through a 7/8" hole bored through the bow and 1.25" tee. Since I wanted to use 1/2" CPVC for the arms this time, though, that wasn't an option. Here's how the assembly worked out for holding the arms and routing the air:
As it turns out, a 3/4" tee will fit into the front space in a 1.25" -> .5" reducing bushing, if the supporting ribs are bored out. I cut them out using a drill press, and seated the tee in place with a rubber mallet. Seating the tee forced the elbow back into the reducing bushing, creating a seal.
For placing the CPVC elbow, I just drilled a 5/8" hole far enough up to keep the bottom of the CPVC elbow flush with the PVC tee. The elbow popped in with a bit of force.
Dealing with the arms: 1/2" to 3/4" CPVC couplers seat very well in 3/4" PVC tees (at least, using a rubber mallet). I bored them out with a 1/2" forstner bit on the drill press, and the 1/2" CPVC was able to slide through with a bit of friction.
The bowstring is 1/16" steel cable, anchored with U-bolts. The arms can be unstrung, as one side is just resting in a notch.
The plunger is a bog-standard SNAP-1 mk2 plunger head, with two alterations. I added one cotter pin behind the catchface endcap, since there is no spring keeping it forward. I also added a second cotter pin in the middle of the plunger head, to better anchor the plunger head to the plunger rod. The trigger is a basic clothespin trigger.
The barrel is currently a basic RSCB...not any limitation, since it needs to be pointed down to prime it, anyway.
I'll get ranges this weekend, as I adjust it.
EDIT: After replacing the ridonkulously short barrel, I'm getting ~80-90 feet. Which tells me that I need a way longer barrel on my bow, because no way should the crossbow be getting similar ranges...
Edited by Carbon, 31 July 2010 - 10:50 AM.