adding backing = draw weight

[timbermoose]

about how much draw weight is added with say a bamboo backing on a hickory longbow? 70" 1.25" at fade and 7/16" at tips with a 9" riser.

a buddy of mine is building one and it came out under weight. i told him to cut it down but he wants the length, he draws to 31". i know it will add something but, how much? it is currently 51# and he wants it to be 65+.

bamboo lams on back and bellie do the trick?

thanks all.

[macbow]

I've never measured the added weight.
I'd put the bamboo on the back only.
It will add quite a bit. I'd flatten the belly of the bamboo till it is close to 1/16 at the edges.
Even better would be to trace the shape on the bamboo then cut out then thin it.
May not make,65 pounds but will be a lot closer. Then with the backing,a couple of inches could be,taken off the length to get closer.

[fujimo]

add the boo, and at the glue up, add in some reflex, and even flip the tips a bit at glue up, and that should add plenty.
if he still is short, he could pike it an inch that will add anything from 3 to 5# depending on design etc etc.
but flipping the tips will also help with his draw length.

do as mac says with prepping the boo!!

[timbermoose]

well i talk to my buddy and we are going to back it with bamboo and then if still not heavy enough we will cut the tips down and go from there. thanks for the help.

now have a new problem with a "new" bow. another thread for that one.

[Pat B]

If not heavy enough after adding the boo backing you can add a belly lam of osage, ipe or other compression strong wood also and that will increase the weight too. With both, plus adding reflex during glue up you should be able to reach 65#. IMO, a better option would be to build another bow to the weight you want. I'm sure you could find someone to give the original bow to.

[LittleBen]

I'm with pat b on this. A 51# bow is still a venerable tool if well made and worth keeping of giving away. Make a new one. Wood is cheap and experience valuable.