Kenny’s FH longbow stack question

[Mike L.]

I’m making a 60” FH longbow using Kenny’s form.  Buddy I’m making it for has a 27” draw on a compound, using a release and D ring and anchoring thumb behind jaw.  I know it’s impossible to know, but he wants the bow to be legal for hunting.  Ideally 45#.  Figuring that he’s going to draw 1”-1.5” shorter on a trad bow, any ideas what target weight and/or stack I should aim for?  I’m using a carbon lam .03, and Gordon Bo-Tuff glass.  Looking for a best guess.

[Crooked Stic]

Message Kenny

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[Forwardhandle]

Well I can't help directly but can tell you what I have found on my bows , I have only used maple & .020 Gordon's carbon ,I have a long draw @30 1/2-31  Used the 40lb. standard stack & ended up at 52 lb so Ruffly plus 12lb @301/2  , I think Kenny mentioned +- 3 lb per inch standard stack  he can correct that if I'm wrong , the .030 carbon is a real swag ,I don't know if any body's used it yet , I realize I'm at the other end of the spectrum as far as draw goes but figured it might help in your swag ! I was thinking of trying the .030 & was going to swag a additional 6 lb over the .020 carbon @ my draw all speculation !

[kennym]

First the draw length, if 26" you will lose 6# from stack/weight on plan.  So need a 51# stack.

Now the carbon.. I don't use it so not much help on it. But you will most likely need to reduce stack for it.

I'm not sure if Ritchie went with the 40# standard @28" and got 12 extra @ 30.5" …

If so the carbon didn't gain all that much in the weight department. Maybe he can help there...

You may get to build two bows to get the right weight, so keep great notes!!

Only one way to know for sure …  R&D 

I would go with 35 @28 on the chart...  (DISCLAIMER-- I don't always hit weight...)

[Stagmitis]

If .30 carbon on back my go to is to reduce the core by 30% to equal that of of .50 glass

[Mike L.]

Kenny,

Last time you helped me figure out the correct stack with carbon, it was my second build, first Forward Handle...  we were trying to figure out 45 @ 28, and came in less than 1/2# over.  Pretty damned close.  That was with .02 carbon, though.   I totally screwed up weight on my next one and ended up so far under that when I tried to figure out why, my best guess was I must’ve just forgot one of the lams.  Thanks for the input.  I’m trying to get the guy to go get his draw length on a trad bow, but he’s all the way o’er in Indiana (where all they got is crossbows I hear)

[Forwardhandle]

My stack total .271 with .020 carbon was 52lb @30 1/2 " sorry should have included it !

[Mike L.]

Kenny, what is the stack for 35#@28?  The template I have only has info for 45, 50, and 55#. 

Stagmitis,

I’m trying to figure out that calculation, and I’m not quite sure what you mean by “equal to .5 glass”.  I am using .040 Gordon glass, so that x2 subtracted from total stack to get the core, Times .30, then subtract from total stack? 

[Crooked Stic]

This works pretty good for me. Take a known bow weight. and divide it into the weight you want. sat it is 45 and you want 50 =1.111 Enter that in the cube root calculator.=1.035 X the old bow stack hieght will give you the new stack. I use this and B Janson and they most times are within 2 to3 thousands from each other
http://www.csgnetwork.com/cuberootcubecalc.html

[kennym]

. 275" should come around 35# @28"  Lighter bows are difficult to figure out...  I'm building a blank now with .270 with .040 glass hoping to hit 32@28"  I can let you know how that goes next weekend I hope. Just glued her up...

I think Stag means he has to lessen stack 30% to be the same with .030 carbon as using .050 glass on the bow without carbon.