Author Topic: Weight to draw to length ratio?  (Read 9781 times)

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Offline SMeeres3030

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Re: Weight to draw to length ratio?
« Reply #30 on: January 14, 2017, 04:11:50 pm »
more pics the day i finished it.

Offline gfugal

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Re: Weight to draw to length ratio?
« Reply #31 on: January 14, 2017, 04:36:32 pm »
Here's my first two succesful bows. They are both 43" NtN and both reached 27 inch draw, but that was before I knew you measured draw length from the back of the handle and not the belly so really they are closer to 28 or 29 inch draws. I would agree the 1:2 ratio is a good rule of thumb. If you convert that to a percentage it is 50% draw length to bow length ratio. My two bows have a 62.8% ratio which is the equivalent of a 64-inch NtN bow drawing 40 inches. So shorter bows are definitely possible however as Badger mentioned they may not be as efficient. Here's the force curve for the second bow. As you can tell it really starts to stack, and is roughly 15% slower than a bow of equivalent weight that doesn't stack. You have to keep in mind the material and design too. These bows were some of my first and they were reflexed when they probably shouldn't have as they now have considerable set, and were too narrow. They were both backed, the first with sinew and the second with paper and cloth. The woods weren't ideal either, the first being Douglass Fir, and the second some mysterious wood I still haven't ID yet. My observations making these bows has told me the compression capabilities of the wood were the main limiting factor. If I had better material, and tillered in a way that minimized damage they would perform much better. To conclude an experienced bowyer could make a good short bow with a similar draw as long as the material was good, (Horn would be Ideal), and the design was better. There is no reason why I see us limiting ourselves to bows longer than twice the draw length. It's a good rule to follow when you're inexperienced or want to play it safe, yet I showed even then its still possible.

*Sorry I Originally had the force curve for the Wool bow at shorter draw before modifying the post. Current force curve is correct.*
« Last Edit: January 14, 2017, 04:44:53 pm by gfugal »
Greg,
No risk, no gain. Expand the mold and try new things.

Offline bubby

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Re: Weight to draw to length ratio?
« Reply #32 on: January 14, 2017, 05:18:57 pm »
Pat we didn't see the bow at all no fd no brace and don't know how the tiller was, could of bent mostly in the fades, even badly tillered bows will last a while. That would also give a longer draw. There are many ways it could of worked right?

 Sure, but if the weight is anywhere near accurate I'm not so sure it would hold up for long with a crowded tiller.

So we agree this is all conjecture 😉

 Yeah but my conjecture is better than yours! lol

Ha!!!
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline PatM

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Re: Weight to draw to length ratio?
« Reply #33 on: January 14, 2017, 05:54:07 pm »
Here's my first two succesful bows. They are both 43" NtN and both reached 27 inch draw, but that was before I knew you measured draw length from the back of the handle and not the belly so really they are closer to 28 or 29 inch draws. I would agree the 1:2 ratio is a good rule of thumb. If you convert that to a percentage it is 50% draw length to bow length ratio. My two bows have a 62.8% ratio which is the equivalent of a 64-inch NtN bow drawing 40 inches. So shorter bows are definitely possible however as Badger mentioned they may not be as efficient. Here's the force curve for the second bow. As you can tell it really starts to stack, and is roughly 15% slower than a bow of equivalent weight that doesn't stack. You have to keep in mind the material and design too. These bows were some of my first and they were reflexed when they probably shouldn't have as they now have considerable set, and were too narrow. They were both backed, the first with sinew and the second with paper and cloth. The woods weren't ideal either, the first being Douglass Fir, and the second some mysterious wood I still haven't ID yet. My observations making these bows has told me the compression capabilities of the wood were the main limiting factor. If I had better material, and tillered in a way that minimized damage they would perform much better. To conclude an experienced bowyer could make a good short bow with a similar draw as long as the material was good, (Horn would be Ideal), and the design was better. There is no reason why I see us limiting ourselves to bows longer than twice the draw length. It's a good rule to follow when you're inexperienced or want to play it safe, yet I showed even then its still possible.

*Sorry I Originally had the force curve for the Wool bow at shorter draw before modifying the post. Current force curve is correct.*


 You are just fooled by the fact that the bows didn't break on the back.

Offline gfugal

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Re: Weight to draw to length ratio?
« Reply #34 on: January 14, 2017, 06:05:00 pm »
You are just fooled by the fact that the bows didn't break on the back.

Are you referring to the fact that I said that the compression capability of the wood seemed to be the limiting factor? I would agree that Tension is the limiting factor in self-bows, but a good backing seems to have prevented them from breaking. The second bow raised a splinter on the back when tillering. It would have been firewood because of its tension limitations if I didn't back it.

Let me rephrase my statement. I believe tension is the limiting factor for self-bows and in bows breaking, however, as far as performance hindrances on an intact-non-broken bow, I feel its compression damage that's the limiting factor. Isn't that what causes the string follow and slower-recoil/hysteresis?
« Last Edit: January 14, 2017, 06:19:40 pm by gfugal »
Greg,
No risk, no gain. Expand the mold and try new things.

Offline PatM

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Re: Weight to draw to length ratio?
« Reply #35 on: January 14, 2017, 06:58:09 pm »
I just meant that holding a bow together with backing gives the illusion that an even greater draw to length ratio is possible.

  Better wood and tillering still won't make that feasible from a performance standpoint.

Offline bubby

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Re: Weight to draw to length ratio?
« Reply #36 on: January 14, 2017, 07:18:05 pm »
Here's my first two succesful bows. They are both 43" NtN and both reached 27 inch draw, but that was before I knew you measured draw length from the back of the handle and not the belly so really they are closer to 28 or 29 inch draws. I would agree the 1:2 ratio is a good rule of thumb. If you convert that to a percentage it is 50% draw length to bow length ratio. My two bows have a 62.8% ratio which is the equivalent of a 64-inch NtN bow drawing 40 inches. So shorter bows are definitely possible however as Badger mentioned they may not be as efficient. Here's the force curve for the second bow. As you can tell it really starts to stack, and is roughly 15% slower than a bow of equivalent weight that doesn't stack. You have to keep in mind the material and design too. These bows were some of my first and they were reflexed when they probably shouldn't have as they now have considerable set, and were too narrow. They were both backed, the first with sinew and the second with paper and cloth. The woods weren't ideal either, the first being Douglass Fir, and the second some mysterious wood I still haven't ID yet. My observations making these bows has told me the compression capabilities of the wood were the main limiting factor. If I had better material, and tillered in a way that minimized damage they would perform much better. To conclude an experienced bowyer could make a good short bow with a similar draw as long as the material was good, (Horn would be Ideal), and the design was better. There is no reason why I see us limiting ourselves to bows longer than twice the draw length. It's a good rule to follow when you're inexperienced or want to play it safe, yet I showed even then its still possible.

*Sorry I Originally had the force curve for the Wool bow at shorter draw before modifying the post. Current force curve is correct.*


 You are just fooled by the fact that the bows didn't break on the back.

So do you shoot a thumb ring or a mechanical release even with a bendy thats way past finger pinch
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline loon

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Re: Weight to draw to length ratio?
« Reply #37 on: January 14, 2017, 07:20:22 pm »
more pics the day i finished it.
looks like it doesn't bend enough in the outer limbs?..

Offline bubby

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Re: Weight to draw to length ratio?
« Reply #38 on: January 14, 2017, 07:24:10 pm »
more pics the day i finished it.

You can't be drawing rhat 25"
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline gfugal

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Re: Weight to draw to length ratio?
« Reply #39 on: January 14, 2017, 07:33:24 pm »

I just meant that holding a bow together with backing gives the illusion that an even greater draw to length ratio is possible.

Better wood and tillering still won't make that feasible from a performance standpoint.
I could agree with that. I don't have much experience doing self-bows. But the way I look at it if a backing will help why not use it? I just wanted to show that if you want a short bow, and he's saying he does, there's no reason you can't make a short bow. If you want a long bow by all means give yourself plenty of working room.

So do you shoot a thumb ring or a mechanical release even with a bendy thats way past finger pinch
I have a mechanical release right now. I prefer the thumb release though, but haven't been able to make a thumb ring yet. Does anyone have a link to how to make one?
Greg,
No risk, no gain. Expand the mold and try new things.

Offline bubby

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Re: Weight to draw to length ratio?
« Reply #40 on: January 14, 2017, 07:40:09 pm »

I just meant that holding a bow together with backing gives the illusion that an even greater draw to length ratio is possible.

Better wood and tillering still won't make that feasible from a performance standpoint.
I could agree with that. I don't have much experience doing self-bows. But the way I look at it if a backing will help why not use it? I just wanted to show that if you want a short bow, and he's saying he does, there's no reason you can't make a short bow. If you want a long bow by all means give yourself plenty of working room.

So do you shoot a thumb ring or a mechanical release even with a bendy thats way past finger pinch
I have a mechanical release right now. I prefer the thumb release though, but haven't been able to make a thumb ring yet. Does anyone have a link to how to make one?


There are some videos on youtube building thumb rings
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline loon

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Re: Weight to draw to length ratio?
« Reply #41 on: January 14, 2017, 07:51:06 pm »
someone made one out of a deer antler, you could pm me if you want me to try to find it
also there's a 3d model for 3d printing

Offline bow101

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Re: Weight to draw to length ratio?
« Reply #42 on: January 14, 2017, 08:01:12 pm »
I draw 28" and have a 60" recurve,   a wee bit of stack and finger pinch but not much because I shoot it 3 under always.  But I will retire it and get at least a 64" bow.  For my wooden bows I prefer 66" and even better a 67".  Lots of guys using 68" glass longbows.
I draw 31" and have a 50" glass recurve... korean though. Doesn't feel too bad for me with split fingers to 27". I don't get why it can be drawn more or stack less than a bow deflexed rather than reflexed at the grip.
even the olympic recurve guys with 70" glass bows thought it was smooth... but it has a good amount of reflex. probably also the static recurves
don't know, are such things just too hard to achieve with wood bows?
guess I should shut up and try.

A 62" bendy D bow would only have 2" more sticking out to get caught on brush. could be mitigated with asymmetry if one wanted? so maybe that'd be good to build.

Didn't mean to bring up FG in the topic.  I dont build wood bows which a ton of reflex, out of my league unless we are talking a static bow....   ??? maybe  :-\  A 42# bow is perfect for this cowboy.  I dont hunt Elk or Bear.
At any rate 64" is good for me @28"  if I was drawing 30"  my forefinger would be screaming in pain.
"The privilege of a lifetime is being who you are."  Joseph Campbell

Offline bradsmith2010

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Re: Weight to draw to length ratio?
« Reply #43 on: January 14, 2017, 08:53:34 pm »
ok maybe I am repeating but was just thinking this important,,
the double the draw plus 10% rule,, also is based on how the bow is going to hold up,,
the shorter the bow more likely to break,, or shift tiller or follow the string,
just becasue a bow can draw further does not mean it is going to perfrom well,,
its hard to make a short self bow draw far without the set effecting the performance,, so it just depends on what you want out  of the bow,, on the other side of that,,,, is you can overbuild the bow and it will shoot like a dog too,,
the double the draw plus 10% is just a middle of the road ball park,, great bows can be built on both sides of that with consideration to the design and type of wood,,,,and the way its tillered,, lots of variables,, but the proof is in the pudding,,
make the bow,, shoot it 5000 times,,shot it for distance or through a chrono,, and you will know if you are on the right track,, :) if all you care about is how it looks at full draw,or how far it will draw,,, then thats not really making a bow,, it has to shoot like a bow to be a bow,,

Offline bow101

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Re: Weight to draw to length ratio?
« Reply #44 on: January 14, 2017, 09:16:05 pm »
Good point bradsmith2010.  I was shooting in a bow the other week,  quote un quote just shooting it in, still had to tweak the tiller on it.  It broke after 60 shots.  After building about 15 bows it was by far the best shooter,  I actually got an excellent grouping one inch from the bulls eye at 18 yards.
 :'( :'(  man was I choked when it broke,  I almost decided  to quit building bows.    :'(
"The privilege of a lifetime is being who you are."  Joseph Campbell