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Main Boards => The Bowyer's Bench => Topic started by: JGR1269 on June 22, 2020, 04:42:11 PM

Title: Stack Thickness vs. Bow Length
Post by: JGR1269 on June 22, 2020, 04:42:11 PM

As a general rule, how much do you guys increase stack thickness when building a 2” longer bow on the same form as a shorter bow? I’m not changing the length of my riser, just increasing limb length.

Title: Re: Stack Thickness vs. Bow Length
Post by: jrstegner on June 22, 2020, 05:17:53 PM

.015 on T/D recurves

Title: Re: Stack Thickness vs. Bow Length
Post by: Crooked Stic on June 23, 2020, 10:50:40 PM

Just longer tip or backing the wedge up ??

Title: Re: Stack Thickness vs. Bow Length
Post by: JGR1269 on June 24, 2020, 07:06:20 AM

It’s a one piece hybrid. I’ve been building 54” bows off this form for 6 years. I recently built a 56” bow off this form but was short on weight. I can go as long as 58” on this form but looking for suggestions on how much to bump op my stack.

Title: Re: Stack Thickness vs. Bow Length
Post by: bjansen on July 04, 2020, 11:07:03 PM

I generally get 4-6# more if I shorten 2” and 4-6# less if I lengthen 2”.  So I would calculate the desired lam thickness using the lam stack calculator and your known lam stacks from your historical bows using that differential

Title: Re: Stack Thickness vs. Bow Length
Post by: JGR1269 on July 05, 2020, 07:30:53 AM

Thanks for the info.

Title: Re: Stack Thickness vs. Bow Length
Post by: Crooked Stic on July 05, 2020, 10:23:53 PM

5-7 lbs. for two in.

Title: Re: Stack Thickness vs. Bow Length
Post by: JGR1269 on July 06, 2020, 09:23:57 PM

I have built several 54” bows that come in around 49-50 pounds with a .310-.311 stack. Anyone care to take a stab at the stack I should go with for a 58” bow at 42-43 pounds?

Title: Re: Stack Thickness vs. Bow Length
Post by: bjansen on July 06, 2020, 10:41:14 PM

JGR, I need to edit my previous comment on 7# for a 2" change - my notes indicate 4-6# instead - sorry about that...thought I had that memorized!

I plugged in your data to the lam stack calculator.  With a .311 stack your 54", 50# bow would produce a 40# bow at 58".  To get a 43# bow at 58" - I think you should use a .319 lam stack.

Mileage will vary of course - you know how it is. If you need a copy of that lam stack calculator, send me your email in a PM - or you maybe able to find an old link on this site.

Title: Re: Stack Thickness vs. Bow Length
Post by: JGR1269 on July 08, 2020, 09:34:46 PM

Thanks Brad. I came up with about the same number with the stack calculator as well. I was hoping to get confirmation that It was correct.

Title: Re: Stack Thickness vs. Bow Length
Post by: Crooked Stic on July 09, 2020, 07:49:31 AM

JGR .295.
And its gonna depend on what the weight range of the bow is lighter bows be less than heavier bows

Title: Re: Stack Thickness vs. Bow Length
Post by: JGR1269 on July 11, 2020, 09:13:51 AM

Glued up yesterday and roughed in this morning. I went with a .300 stack at the butts, 58”, with 7 5/8” brace and it’s 46#@27”. She’s 1 1/2” at the fade outs and 5/8” at the tips so by the time I take the limbs down to my usual width and work the tips I should be about right.