Is there a formula for figuring how many wood laminations are needed (thickness, etc) to reach a desired poundage?
Or is it trial and error?
When I made my son's bow, about 1/4 inch oak board with a backing of less than 1/8 walnut, I expected about 5-10 pounds more draw.
I realize there are a ton of variables; kind of wood, thickness of each lam., width of limbs, length of limbs, etc.
Do a search here for formula, recipe, laminations, and you will start to get some more insight into it.
As you say, too many variables to tell without a lot more info about limb width, thickness, taper, riser length, r/d, etc...etc...etc...
Bingham has his formulas in his catalog but they are for his bow plans. Most bowyers do trial and error. They make a particular bow and keep records on what they used for that bow. What they wanted and how it actually came out. Then they tweak the combinations until it is just right. Too many variables though unless you are for sure just going to make one type of bow and only that type with the same woods.
Would the same number of lams in a narrow limbed longbow equal that of a wider limbed recurve??? I would think that width would play a big role in poundage.
I got a call from fedora yesterday that TOTALLY confused me (I know I know...not to hard to do :-))
I was basing my lam thinknesses of specs that my friend as recorded from all his bows (since I'm using his forms, and jigs, etc)..and he figured I needed a butt thickness of .230 or .235 at the fade...so I ordered accordingly. but fedora called yesterday and said I'd end up 15-20 pounds lighter than what I was shooting for...
but there are so many factors that at involved....limb mount angle, limb width, form design (where the curve is), that is really hard to predict. so I let him convince me to up all the thicknesses....we'll see when it gets here....