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Main Boards => The Bowyer's Bench => Topic started by: Michael Pfander on December 06, 2015, 10:39:00 AM

Title: Tri-lam stack thickness
Post by: Michael Pfander on December 06, 2015, 10:39:00 AM

I want to build a tri-lam as my winter project.  I need some help on the taper and stack thickness for 55# @ 28" 66" bow.  I am planning on .002 taper on the core, parallel on back and belly.  The riser will be 18" fade to fade.
MAP

Title: Re: Tri-lam stack thickness
Post by: Bowjunkie on December 06, 2015, 03:30:00 PM

We need more information. What materials will be used? What kind of side profile? Straight, d/r, semi or full recurve?

Title: Re: Tri-lam stack thickness
Post by: Michael Pfander on December 08, 2015, 10:08:00 PM

I plan on using bamboo for the back, yew for the core, and osage for the belly.  It will have a mild r/d proflie.
MAP

Title: Re: Tri-lam stack thickness
Post by: mikkekeswick on December 09, 2015, 03:23:00 AM

Use more taper for sure. R/d bows like to have parallel width limbs out to about 10 inches from the tips. This really helps maintain the reflex in the mid to outers and also helps with limb stability.
I use 0.005 taper.
you can't really use accurate stack info on a wooden bow because the materials aren't homogeneous. Aim for your stack to add up to 1/2 inch at the fades and you should be ok.

Title: Re: Tri-lam stack thickness
Post by: LittleBen on December 09, 2015, 09:54:00 AM

X2 what Mike said.
Definately use more taper. It'll mean less tillering in the end. And take his advice on he width taper ... This guys knows this type of bow.


FWIW
Only time I've had luck with stack is making multiple bows for the same ipe board, and even then it was maybe within 10%. Change boards, and everything changes.