Reality/Logic Check, please

[KenH]

Last year, Cardboard Duck built a wood-glass bendy-handle flatbow, described here:

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=009791#000000

It was 61" long, 1.25" wide tapering out to 3/4" at the tips, had a stack of  .570, and came in at about 100# @28".

So I want to build somethings similar, but shorter, and only 30# draw.  If I plug CD's bow info into BJansen's Lam stack Calculator, discussed here:

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=007699#000000

I get a new stack of .382 for a 30# draw that is 61" long and 1.25" wide.  

Here's where I want the reality check.

If I want the new bow to be 57" instead of 61" (I have some beautiful Kentucky Coffeetree lams from Troy Breeding) that would be the same as piking that 61".382stack/30# bow by 4", or a gain of about 10#s .  If I then go to the stack calculator and plug in 20# instead of 30# for the desired new bow weight, I get a new stack height of .333.

Does that sound right and or make sense?  Help!

[jsweka]

I follow your logic, but if I were doing it I would assume piking it first - making the bow 110# and then sticking that into the stack calculator.  Going from 110# down to 30# would suggest reducing the stack from .570 to .370.

I always go with a higher stack estimate which gives me some wiggle room to reduce weight by narrowing the limbs some if need be.

[KenH]

Thanx John.  See, that's why I wanted the reality check.  Doing it your way also works. But which is "more right"?   I was thinking to go lighter and my wiggle room would be to pike the resultant bow if I needed to gain weight (to me shorter is always better)...

If I average the two results I get a stack of .351 !!

[jsweka]

0.351 sounds good too.  
Just make sure you hit that last one-one thousandth dead on, otherwise you will totally miss weight    

[KenH]

Ayup.  That .001 will make or break the draw weight, I'm certain.        :eek: