Hi guys,
I've built a few straight limbed longbows using Bingham's kits with good results. For my next bow project, I want to deviate a bit from Bingham's recipe and also want to try grinding my own lams (It's good to have a father that is really big into woodworking and just bought a drum sander.) This one will also be a straight limbed bow (just love that classic look).
Here's my tentative design specs:
68" nock-to-nock
15" riser
1.25" width at fades
0.5" at string groves
Laminations (from back to belly):
0.050 black glass
0.080 hard maple (parallel)
0.080 hard maple (parallel)
0.080 purple heart (parallel)
0.110 hard maple (0.002 taper)
0.050 black glass
I'm hoping to hit the high 50/low 60 pound range. Will this get me there? Any advice on lam thickness or additional tapers would be appreciated.
Thanks,
John
Hi John, That is off the Bingham charts!! 70# is .435 total stack! Check this out...
http://www.binghamprojects.com/Page%2019.pdf
OOps shoulda read closer!! Marty can tell ya what you need,he builds lotsa 1.25 wide bows...
Kenny - Yep, a little narrower than the Bingham blueprints and kits. With the last bow I made from one of their kits (cherry and actionboo lams), I narrowed the limbs to 1.25" and cut the riser back from 18" to 15". I let them know this when I was ordering the laminations and what they sent me was pretty close to what I specified above except that one of the parallels was 0.070 instead of 0.080. That bow ended up at 54# and I was going for 60#. Still a nice shooting bow and actually the one that I'm hunting with this year. So I figured if I just beefed up one of the lams I could probably come closer to 60#, but wanted some additional opinions. In the other bows I've made where I followed their design, their lamination kits did come within a pound or two of my desired weight.
They are usually real close on the stack. Sounds like you have it nailed. Marty should check in on it,he will know more than me,mine are mostly 1.5 and d/r.
A .450 stack with .004 taper, a 16" riser, and 66" NTN will give me a 55# bow. Mine come off the form with 1/2" of string follow. Let's do what I would do.
add two inches nock-nock - -7#
subtract one inch from riser - -3.5#
.002 taper vrs .004 - +2# ??
Straight profile vrs string follow - +2# ??
If I were building it, I would expect around 48@28 with your recipe. If it were me, I'd have to go with a stack of around .490. Results do vary though. I typically need a thicker stack than most.
Marty - Thanks for the advice.
This bow is going to be my Christmas present to myself. I'll post some pics when I get it done.
Another general question - How much variation do you see in finished weights using the same design, but different woods for laminations?
I've found red cedar and walnut to come in about 5# lite on a 50# bow. That is complete core(red cedar may be even more) I only use red cedar for veneers tho due to strength. YMMV
Thanks Kenny - I guess this really points to the advice Jack Harrison gives in his book - Take good records on each bow you make.
Exactly right!! :thumbsup: