Tillering a xbow prod?

[Thesquirrelslinger]

Well, I want to make an all wooden xbow for fun. I intend it to be about 80 pounds with a 15 inch powerstroke. I have elm and red oak for making a prod.  I need to know how you would make and tiller such a bow.
Thanks,
Squirrel

[adb]

I've made 3 xbow prods out of self yew. All hade an 8" power stroke, 3" brace height, and were 32-40" long. I made 1 with a rawhide backing. I made and tillered them the same as any other bow. Draw weights from 60-80#s. The last one I made had 1" of tip rise.