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Main Boards => The Bowyer's Bench => Topic started by: pditto613 on April 07, 2019, 06:38:06 PM

Title: Severe stack help needed
Post by: pditto613 on April 07, 2019, 06:38:06 PM

Making a kids bow.  The plan is glue it up as 2” blank then split it in half to make 2 bows from one blank.  Everything went as planned except draw weight.  The roughed out blank pulls 30# @ 18”. I was shooting for 10 to 12# .
Bow is 7/8” wide, 33 1/2” notch to notch.  Stack is two .030 glass and one parallel lam at .110.  Total stack .170.  Riser is 11 1/2” fade to fade.
Any and all help is appreciated
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Title: Re: Severe stack help needed
Post by: kennym on April 07, 2019, 06:47:12 PM

According to B Jansens stack calculator, you need .125

Handy tool, but don't know how it would work on a real light bow...

Google b jansen stack calculator and click enable editing at top , then enter your stats and what you want weight to be...

Title: Re: Severe stack help needed
Post by: Shredd on April 07, 2019, 08:37:22 PM

Looks like you are bending way too much at the fades...  You may want to put a taper in there instead of a parallel...

Title: Re: Severe stack help needed
Post by: pditto613 on April 07, 2019, 09:57:10 PM

Thanks Kenny. Knew I could count on you for input. 
Shred you are right about about taper.  I was going for simplicity with the parallel, but the tips hardly flex at all.  Thought I could get them to flex by tapering the sides, but the bow just isn’t wide enough to start with.  If Kenny is right about the stack not sure how much taper I can get in a .65 lam.  Have to do the math.

Title: Re: Severe stack help needed
Post by: pditto613 on April 08, 2019, 07:57:57 AM

Checked BJansen calculator. A .125 stack will give me 12# like Kenny says and that jives with what I figured as well.  If I use a .065 lam tapered to .002 I will still have .030 at the skinny end.  My hope is to come in at 10# at 18".  Thoughts?  In the mean time if anyone knows any pygmies, I have a couple of bows cheap!

Title: Re: Severe stack help needed
Post by: TradBowyer on April 08, 2019, 10:19:24 AM

I build hill style kid bows. I use 12" riser, one 0.125 parallel lam, 0.040" glass. limbs are 1" wide, bows can be cut any length but my boys is 48". 23@ 20

Title: Re: Severe stack help needed
Post by: pditto613 on April 08, 2019, 06:18:55 PM

That sounds like the 48” version I make.  I just screwed up the math converting to a 36” version.  Now I am gun shy

Title: Re: Severe stack help needed
Post by: kennym on April 09, 2019, 01:18:46 PM

A .065 butt and .002 taper will only be 17.5” long with .030 on thin end by my math in my head . That could be wrong tho....
LOL

Title: Re: Severe stack help needed
Post by: pditto613 on April 15, 2019, 09:26:59 PM

You were right on Kenny. Used a .065 lam with a .002 taper.  Bow came in at 12# @18”.  Should be 10# after finish sanding.  Much easier for my granddaughter to shoot

Title: Re: Severe stack help needed
Post by: kennym on April 15, 2019, 09:36:19 PM

I just used Brad Jansens calc !! He was the one that was right!!

Good deal tho!!