lamination question

[giff]

I am going to make a mild R/D longbow, and want to know whether i should use 2 lams @.075 with .050 glass back and belly, or 1 lam @.150 with .050 back and belly. I am using walnut and hoping for 50-55@28

thanks in advance

[giff]

p.s. it will be 64"

[mater]

At least the two. But Im thinking its going to take more than that to get to 50+ pounds. I never make a laminate thicker than .100.  Check binghams web site for there chart.

[giff]

the chart says .374 will give 45# with a 68" bow

[giff]

does the chart show total limb thickness, or just the core?

[Lee Robinson .]

Three important factors besides bow length and poundage are...

1. How long is your riser from fade out to fade out? (Major factor)

2. How wide do you want your bow to be? (major factor)

3. How much backset (total reflex) does your bow have? (a factor, but not as critical as the other two)

I just started making bows, but I would never use just one lamination as a core. I don't think I will ever use anything over 0.100 either, but in most cases I will stay under 0.08 as a max lam thickness.

If I needed a total core of 250, I would use about 90-100 of synthetics (50 on belly and 40 or 50 on the back) and 150-160 natural materials. Of the 150, I would break it into 50, 50, and 50-60 for the remaining lamination.

[Swissbow]

I got an excel sheet from Jason that will help you determine the stack for a longbow with a mild d/r-profile. I have used it for 7 bows so far and it has always worked perfect for me. You can download it here ( in the download section )...

http://swissbow.com/

Generally I choose my stack 5 - 10 lbs heavier, that gives me enough room for the tiller and I can make the tips nice and thin.

I agree with Lee on not making the lams to thick, because you might get in trouble if the radius on your fade out is to narrow. On my last bow I wanted more taper so I had to go thicker and it was quite a fight to get nice glue lines at the fade out.

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Andy

[JamesV]

I just built a 62" NTN R/D longbow that came in at 50# @28" The total stack was .385

[K30bowfisher]

The bow I built a month ago or so came in 56# at 30". Total stack was .405", .05 glass, 3 parallels .065, one .002/in taper .110 at the thick end. This was for Bingham's r/d longbow design.