hey guys just curious if anyone has built any laminated longbows at around 70lbs? if so how thick were your laminates? did you use glass?
Well, an old article that I found mentioned that for a 50# bow you would use a .175 core, with .050 back glass and .040 belly glass. For those sort of generic 60s/70s mild recurves. I'm guessing you might go upwards of .2 core and .05/.04 glass for 70#s...
If you look on KennyMs site I believe he has core and glass thicknesses for upwards of 70+ pound bows. You might check the Bingham Projects site too.
That's a hard question without more information.
What will the profile be? Bow length? Riser length? Do you want to use glass or will it be an all wood bow?
it will be a 68 inch long straight limb. with a 16 inch riser and i am gonna use glass
I'd check with Kenny, but I'm guessing in the neighborhood of around .440 ish total stack. You might also check with BigJim. He does a lot of heavier bows. Might be able to point you in the right direction.
I was going to answer this but after consulting my 'recipe' book for the 80#er I built some time ago, I must have been on the happy juice as its all garbled. I know the initial build came in way heavy at 75# @ 24''. That was with a total aboo wood stack of . 490 plus 2 x .040 glass. I got it down to 74# at 28'' The glass would have been a little compromised as well. Better to have gone with .050 glass. i knew it was too much for the client but that was what was ordered. I did another which came in at 70# but can't find my notes. Sorry.
Depends on your degree of taper too. I have a few that are right on 70# @ 28". They are around .480 - .500 total stack thickness, but that was back when I was putting more taper in the limbs... about .005/1" - .0055/1" respectively.
Those are both 64" ntn mild/moderate d/r longbows, about 1 1/4"wide, with trapped limbs and 16" risers.
I haven't built a straight limb bow myself.. but Bingham's chart shows their 68" straight limb design needs a 0.435 total lam thickness for 70# @ 28"