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Main Boards => The Bowyer's Bench => Topic started by: Jeremy Bays on June 25, 2015, 01:45:00 PM

Title: Longbow Lam Formula?
Post by: Jeremy Bays on June 25, 2015, 01:45:00 PM
Thanks for the help so far.  Greatly appreciated.

I think for my first fiberglass laminated bow I would like to produce a simple straight limbed longbow.

I would like a draw weight about 50 pound or so at 28 inches.  The bow should be about 68" tip to tip...or open to other ideas.

Any idea on a laminate formula, using Big Jim's bow woods, that would get me in this ball park?

Thanks
Jeremy Bays
Title: Re: Longbow Lam Formula?
Post by: Robertfishes on June 25, 2015, 02:24:00 PM
0.390" would get you close with the right length riser..
Title: Re: Longbow Lam Formula?
Post by: macbow on June 25, 2015, 05:14:00 PM
Your best resource is your vendor.
Big Jim certainly should know.
Title: Re: Longbow Lam Formula?
Post by: jsweka on June 25, 2015, 08:36:00 PM
Here's a recipe for a straight limbed bow I recently made that came out at 50# @ 28".

16" riser
1.125" wide at the fades and remained that width 14" from the center of the bow, then tapering to 0.5" at the nocks

Materials - from back to belly
0.050 glass
0.002 tapered lam - 0.110 butt thickness
parallel lam - 0.100 thickness
0.001 tapered lam - 0.110 butt thickness
The riser
0.002 tapered lam - 0.090 butt thickness
0.050 glass

Total stack = 0.510
Total taper = 0.005

I also round over the edges of the limbs really well.
Title: Re: Longbow Lam Formula?
Post by: Robertfishes on June 25, 2015, 09:40:00 PM
Jeremy, jsweka has given you a great formula for a sweet shooting bow. I looked at my copy of Binghams bow weight chart and typed in 0.390. I think their bow is 1.50 inches wide at fades. I had their DVD in 2009 and was going to build a straight limb bow but started building recurves instead.. I no longer have their plan or DVD.
Title: Re: Longbow Lam Formula?
Post by: Jeremy Bays on June 26, 2015, 12:48:00 AM
Thanks jsweka for the information.  I will start gathering supplies shortly.  Hope to have something to post soon.

Thanks all..
Jeremy Bays
Title: Re: Longbow Lam Formula?
Post by: monterey on June 26, 2015, 02:11:00 PM
Whatever "recipe" you use, keep in mind that any changes in width, length, riser length, thickness, taper rate, etc., will change your end result.  Very small variations in stack thickness can have significant effect.

If you go with your suppliers recommendations, you will soon have some great photos to show off here!