Taper thickness

[mzombek]

Hi folks, been awhile since I been on your site. When doing the stack up on longbow limbs, what determines the thickness of the taper lam?

[Kirkll]

it might be helpful to reword your question. Long bow tapers vary from .002-.004 total forward taper depending on the design. Many hybrid long bows use .003  FT. and the D shape tend to run a bit more FT...

The thickness is typically measured with the glass as a total "Stack height" Some measure this at the butt. my self i measure my stack  at 10" from the butt so i can shift the tapers to adjust the height.       Kirk

[kennym]

Another view on your question-  I don't make any taper thicker than .130 at butt, and a bit less if I can.  Then the rest of stack is veneers, parallels ,more tapers if needed, and glass.

And on risers with a ramp up to belly to a flat on riser, make sure you can bend the taper butt fairly easily up that curve.

[Mad Max]

what they said

Example

.400 total stack
.040 glass back
.040 glass belly
Now you have .320 for tapers and parallels
.130 kenny M taper
.095 parallel
.095 parallel
add those up =.400

[Kirkll]

Another view on your question-  I don't make any taper thicker than .130 at butt, and a bit less if I can.  Then the rest of stack is veneers, parallels ,more tapers if needed, and glass.

And on risers with a ramp up to belly to a flat on riser, make sure you can bend the taper butt fairly easily up that curve.

That’s a really good point Kenny… when I rip my lams I start out with .125 on the table saw, and start from there. Most all of my tapers never exceed .110 at the butt. Most are about .95 to .100 and are sanded down from there. 

I like to use .080 or less thickness in the working portion of the limb and use 3-4 lams in the core.  The more lams you use, the less spring back you get coming out of the form. It holds the shape better.   

I knew a guy years ago who got a great deal on a huge quantity of veneer stock that was running about .025- .030 thickness, and he was building recurve bows just using veneer stock in the core.  It was pretty impressive how torsionally stable those limbs were on very light draw weight bows….. but he used a lot of EA 40 laying them up.     Food for thought….  Kirk



   Kirk