The crossbow is one of those inventions that changed history. Prior to its invention, an archer might train for years before developed the strength and proficiency to be an effective warrior. With the crossbow a modicum of training could turn even the meanest peasant into a soldier. Additionally, through the use of mechanical cocking mechanisms, brute strength was no longer a limiting factor.
All that aside, here's my attempt to design and build a crossbow.
Please note, this should not be attempted by anyone, it can kill you, your dog, your ... etc. etc.
Step 1: The prod, or bow.
The overall length is 50" with a width of 2 1/2" tapering to 1/2" at either end. The thickness is 7/16"s.
The nocks, are like the nocks I used previously, how ever instead of tying them on, I used hardwood pins.
Please note, one edge of the bow is kept straight.
I did back the bow, with denim. I simply layed down a coat of Titebond and then a piece of denim which I rolled into the glue with a dowel, similarly to using a rolling pin.
Step 2: The Stock
The Stock was whipped up in ProE, it's really just two rectangles, one 3x20 and one 5.5x14.5 offset and joined with a spline to make it "pretty".
So grab the dimensions off the picture and cut out two from3/4 inch ply (it was what was handy)
Once the two pieces are cut, they are screwed together with wood screws, since they will need to be disassembled several times.
Now's as good a time as any to use your jointer to even out the top edges of the two stock pieces, if you don't have a jointer (I don't). screw the stock to a board and just use your tablesaw. But those top edges must be flat and level.