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New bow started(again, 1/4/2022){ and again 8/10/22}

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superdav95:

--- Quote from: BowEd on December 06, 2022, 02:05:03 pm ---
--- Quote from: Pat B on December 04, 2022, 12:34:47 pm ---Ed, I haven't tested the weight lately and it really doesn't matter at this point. I can tell by floor tillering it will be lighter than a hunting weight bow. If I can get my finished sinew backed bow to come out at 40# to 45# I'll be happy. I will also be adding a thin rawhide backing over the sinew. My main concern is getting the overall bow tillered well and adding a good sinew layer to it. I can still go back and heat treat more before sinewing.

--- End quote ---

In your picture I seen you had this bow close to your full draw tillering.Personally I don't like to stress the wood hardly at all before sinewing.I try to not go past 20" drawing it.Then extrapulating a ball park estimate within 5#'s of what the draw weight will be at 28" or your full draw.Then with the knowledge of knowing what depth sinew will give the bow I can usually get within 5#'s of full draw weight while needing to remove very little wood from the belly while tillering.
I think it gives the bow prospect the best chance to be a very efficient bow broken in.
I've found reheat treating numerous times does'nt actually help much.Once it's stressed the stress goes deeper than just the surface on the belly along with the stretching on the back.Even though sinew goes over the back.

--- End quote ---

This is what I’ve been finding as well. +1 for what Ed said.  I usually get just past brace then sinew it.  Ed’s right on this from what I’ve noticed in my bows.  I stick with 50% wood/25%sinew/25%horn.  On wood and sinew only bows it depends on the width of the limbs but generally a standard flat bow 60%wood/40% sinew by thickness.    Stressing the wood prior to sinew puts more stress on the sinew then there needs to be.  Having a balance share of stress on the combination of sinew glued to the unstressed wood core makes for a better more efficient bow in the end.  Looking good so for pat.  Lookin forward to rest of this build. 

BowEd:
That elm is some good bow wood Pat.Look forward to seeing what you get from this design.
When tillering there's a certain weight I want at 20" that will conform to a 45 to 50 pound bow after heat treatment.That's usually around 32 pounds + or -.
Most all good dry bow wood will not show stress at that draw length unless badly tapered or too narrow for design.
Every pound or two less than that will lose close to 5 pounds of full draw weight.
Knowing the thickness of sinew I need I then can put that amount onto the bow to get my preferred full draw weight.
Like Dave said percentage overall wise.
50/25/25 percentage core/horn/sinew is a good more stable percentage because of the thicker stabilising core.Going 33/33/33 percentage will be more unstable.More time consuming and having a wild child on your hands for a while because horn is a lot more elastic than wood,but it's still doable.Using a peg board helps settle them down.The added benefit of thicker percentage horn will help for less set also.
It's still a little bit of a guessing game but it'll put the bow very close to what is desired.Being slightly overweight is good though.It leaves room for fine tuning the tiller.
This works for me on bows from 58" long to 68" long.I'm sure going shorter might change some of the estimates.

Pat B:
Ed, I took your advice and went back and re-tempered the bow on the reflex form darkening the color a good bit. Here is where she is right after removing her from the form...


I have not strained her yet since tempering. We have been in a wet period for a couple of days with a couple more rainy days to come. Once we dry out a bit I'll check the tiller out to 20" then prepare for sinewing. Her overall length is 65"t/t with about 18" to 20"of working limb on each side. In the end the t/t length will be shortened by maybe 2" after I shape the tips. I've been thinking about how I want to shape the tips to reduce as much weight as possible without weakening them or losing the lateral stability.

PEARL DRUMS:
You are getting closer now, Pat. Don't screw it up :)

Pat B:
You know me all too well, Chris.  (--)

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