I'm an SCA member who wants to build a couple of period style crossbows, for target archery (and combat archery, where they use modified bolts with special tips). I have never built a crossbow before, but I have been reading everything I can find on the topic.
I recently got a chance to examine a very basic crossbow someone had built for combat archery, and was given the chance to shoot it at some targets during the monthly archery practice. The release was a pin lift type (not sure of the correct term), with a lever on the top of the tiller, not a roller nut type with the lever on the bottom. The prod was made from a fiberglass boat stay, cut down into a longer and a shorter piece, with the shorter piece against the front of the stock. Both pieces were wrapped/wound with cord and secured to the tiller by a bridle. Shooting it, I noticed that it took a lot of pressure to lift the string to the point where it fired - so much so that it was difficult for my wife to shoot it, and this made aiming the weapon difficult.
The gentleman who built the crossbow was following plans he had gotten from somewhere online, and the main consideration was economy of price. He bought the string from an archery supplier (North Star Archery, I think) and the fiberglass boat stay from a local marine supply store. He used scrap lumber and such for the rest of the bow. His cost was under $50, and he intended it primarily for combat archery (where it might get damaged).
An afternoon of shooting his crossbow taught me several things - I want a roller nut release for target shooting, with the trigger lever on the bottom of the tiller where you can use a better grip to move the lever. I want to make my crossbow as inexpensively as I can (my budget for parts is very small) but I do not want to use the cut down fiberglass boat stay for the prod. I say this having read the detailed instructions for assembling his crossbow plan, and realizing that it is likely to be messy and potentially dangerous. I also want a stirrup on the bow so my wife (who is half my size) can cock the crossbow without injuring herself. Since we shoot at targets that are 20, 30 and 40 yards away, I need the crossbow to be strong enough to accurately hit the targets, but not so strong that my wife comes to hate her crossbow.
I intend to purchase a string from a supplier (rather than try to make my own), and I believe I can manufacture a suitable roller nut, release lever and tiller from scraps at work. My biggest concern is the prod.
Having said all of that (and thank you for reading it) here are my questions:
1. Is there a source for aluminum prods that you know of? I see Alchem Inc sells steel ones for $65, but that would pretty much demolish my budget, and frankly I'm not sure if any of them are light enough for my wife to draw!
2. Lacking a source for pre-made aluminum prods, would making my own out of aluminum flat bar stock (6061 or something similar) be a valid option?
3. Do you have any other suggestions for an inexpensive prod?
4. I have downloaded the plans offered at Alchem's website, which show the placement of the various parts in a roller nut type crossbow. If you have seen these plans, would you have any warnings or suggestions regarding them?