lam thickness

[cabinman70]

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?

[KenH]

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.

[jsweka]

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?

[cabinman70]

it will be a 68 inch long straight limb. with a 16 inch riser and i am gonna use glass

[talkingcabbage]

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.

[bigbob2]

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.

[Bowjunkie]

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.

[Bowjunkie]

Those are both 64" ntn mild/moderate d/r longbows, about 1 1/4"wide, with trapped limbs and 16" risers.

[Robertfishes]

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"