Hi Fellas I have been studying about making glass bows I have made self type bows for a few years now but working my way to make one with glass I usaly don't like to ask questions unless I can't find the answer my self some where but one thing that's been puzzling me is on a average self bow the belly tapper is on average about 1/16 every 5 1/2-6 in. But on glass bows you see much flatter tapper 0.001,0.002,0.003 Ect ,could sombody explain that to me , could it be different front profile Ect ? I have googled the heck out of it but no answer ?
I have measured hundreds of factory bows, and .003 taper seems to be the magic number.
James
I would think it has to do with the addition of the glass making things stiffer.
Also for narrower bows you need more thickness taper, as you have less side taper. :)
It has to do with the strength of the wood or composite in the case of a glass bow. Fiberglass adds a considerable amount of bending strength to the overall limb composite. Taking 0.003" off the thickness of a glass bow may equate to 1 lb less draw weight. You might have to take 0.010" off of a self bow to lose 1 lb of draw weight. It's the same reason that most self bows start out at almost twice the thickness of a fiberglass bow, they aren't as strong.
A hypothetical example of 3 bows with similar width profiles may have the following taper rate to produce the same bend profile:
Elm Self bow- 0.010"/inch
Bamboo backed Ipe- 0.007"/inch
Glass bow- 0.003"/inch
And as mentioned, the width taper affects it too.
Bmorv that was a excelent exsplanation thank you and the 0.010 is where I start tapper wise with a self bows your exsplanation makes prrfect sense to me.
It is linked to the width profile. Parallel width limbs need more thickness taper. Pyramid width tapered limbs require less.
There is no 'magic' number for all designs.