Author Topic: How can i improve this bow  (Read 1358 times)

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Offline Iskelton

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How can i improve this bow
« on: October 03, 2021, 03:26:38 am »
I want some feedback and some help on where I can improve for this bow. some background information, this bow is a 51inch ntn pacific yew wood bow, pyramid design, with a 1-1/2 wide, 4inch long handle, and 2inch wide limbs that tapper down to 1/2inch. it braces at about 4inches and draws only 18inches at 50lbs then i feel a large amount of what i think is stacking. I was hoping for some feedback on design, tiller, how to increase the draw length and anything else that could help me improve my bow making! thanks so much!   

Offline Iskelton

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Re: How can i improve this bow
« Reply #1 on: October 03, 2021, 03:33:21 am »
here is a photo

Offline Del the cat

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    • Derek Hutchison Native Wood Self Bows
Re: How can i improve this bow
« Reply #2 on: October 03, 2021, 03:57:20 am »
I'd suggest it's not stacking as such, it's likely the inefficiency of such a short draw (e.g Your body isn't working efficiently at that draw, not using shoulders or back, can't get into the bow).
The only way you'll actually see if it is stacking is to plot a force draw curve.
The string angle (angle between sting and bow tip) is no where near 90 degrees which is the point after which one would expect stacking would start.
The outer 1/3 of each limb could flex a little more. A pyramid design will tend to be stiff in the outers due to the physical limitation of having to have the tip big enough to make a nock, where it should theoretically taper to zero width for circular tiller.
This video shows how it works...(you may want to fast forward through to about 4:55!)
https://www.youtube.com/watch?v=WdQCB5Txv_E
The way to get it to draw more is also to simply pull it further! If it's Pacific Yew, it should be able to take it.
Del
PS. I once had a guy trying to draw a warbow say to me. "Wow I can really feel it stacking"
I replied , "That's not the bow stacking, it's you!"  ;D He'd just reached his physical limit.
« Last Edit: October 03, 2021, 04:08:59 am by Del the cat »
Health warning, these posts may contain traces of nut.

bownarra

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Re: How can i improve this bow
« Reply #3 on: October 03, 2021, 04:05:47 am »
Welcome to the forum :)
First things first you don't say what your drawlength is. If you are aiming for a 28" draw then a stiff handled bow would normally be made with a 4 inch handle, 2 inch long fades and 28 inch for each limb - working out to around 64 inch nock to nock overall length. 66" - 68" might be a bit better when you are starting out. For a bendy handled bow (handle is widest part of the bow) you can go shorter - around double the drawlength (28"x2) or 56", again a little longer will make tillering a bit easier.
So with your stave at 51" long, even made with a bendy handle you would struggle to get more than 25 - 26" draw.
As for what you can do to your bow now. It is bending too much in the middle and inner limbs. Remove wood from the mid limbs out to the tips.
It looks like it doesn't really get thicker at the handlke section? A photo would help. When you narrow (narrower than the limbs) the handle section it has to get correspondingly thicker or else it will bend excessively there. The middle of the bow sees the largest forces.
« Last Edit: October 03, 2021, 04:11:16 am by bownarra »

Offline bassman211

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Re: How can i improve this bow
« Reply #4 on: October 03, 2021, 10:46:22 am »
Make the limbs longer which will reduce draw weight, and lengthen your draw.   Beyond that you could sinew back it also. That would get you 25 inches of draw. Short bows like yours made by plains natives were made for horse back, and nearly point blank shooting for killing buffalo, and shot pinch finger, and low braced. Typical draw of those bows would be 16 to 20 inches, and they will fell stacky.

Offline Iskelton

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Re: How can i improve this bow
« Reply #5 on: October 03, 2021, 01:21:49 pm »
I'd suggest it's not stacking as such, it's likely the inefficiency of such a short draw (e.g Your body isn't working efficiently at that draw, not using shoulders or back, can't get into the bow).
The only way you'll actually see if it is stacking is to plot a force draw curve.
The string angle (angle between sting and bow tip) is no where near 90 degrees which is the point after which one would expect stacking would start.
The outer 1/3 of each limb could flex a little more. A pyramid design will tend to be stiff in the outers due to the physical limitation of having to have the tip big enough to make a nock, where it should theoretically taper to zero width for circular tiller.
This video shows how it works...(you may want to fast forward through to about 4:55!)
https://www.youtube.com/watch?v=WdQCB5Txv_E
The way to get it to draw more is also to simply pull it further! If it's Pacific Yew, it should be able to take it.
Del
PS. I once had a guy trying to draw a warbow say to me. "Wow I can really feel it stacking"
I replied , "That's not the bow stacking, it's you!"  ;D He'd just reached his physical limit.

Haha that’s awesome, thanks so much for the reply! Helps a lot I’ll put it back on the tiller tree then to get those limbs to bend more and reduce the draw weight.

Offline Iskelton

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Re: How can i improve this bow
« Reply #6 on: October 03, 2021, 01:34:43 pm »
Welcome to the forum :)
First things first you don't say what your drawlength is. If you are aiming for a 28" draw then a stiff handled bow would normally be made with a 4 inch handle, 2 inch long fades and 28 inch for each limb - working out to around 64 inch nock to nock overall length. 66" - 68" might be a bit better when you are starting out. For a bendy handled bow (handle is widest part of the bow) you can go shorter - around double the drawlength (28"x2) or 56", again a little longer will make tillering a bit easier.
So with your stave at 51" long, even made with a bendy handle you would struggle to get more than 25 - 26" draw.
As for what you can do to your bow now. It is bending too much in the middle and inner limbs. Remove wood from the mid limbs out to the tips.
It looks like it doesn't really get thicker at the handlke section? A photo would help. When you narrow (narrower than the limbs) the handle section it has to get correspondingly thicker or else it will bend excessively there. The middle of the bow sees the largest forces.
[/quote]


Thanks for the warm welcome! My normal draw weight is 26-32 inches with a longbow but for this guy I was lucky enough to get a small piece to work with. The handle section is a work through the handle, 4 inches and not much thicker, if at all, from the fades, I’ll post some more photos!