Primitive Archer
Main Discussion Area => Bows => Topic started by: SMeeres3030 on January 13, 2017, 04:59:23 pm
-
Hi I'm am curious if there is some ratio or rules or guidelines to follow for length of bow to draw length? I finally broke my very first bow I made! So sad. It was a yew self bow 58" ntn 72# @ 30.5".
I've shot it for 1 year now and it started ticking yesterday when shooting. It may have been from extreme cold -26c but it ticked them boom into 10+ pieces. Anyway I have a few more in the making but just hoping for feed back.
-
yes you went way past the ratio,, :) you need about 68 to 70 inches for a self bow,,to draw 30 inches,,
-
Its not just an issue of over stressing wood which is very important but also too short of a bow will stack at longer draw lengths. You get low energy output ratio for your peak draw weight.
-
Sorry to hear your bow broke, that is always frustrating...
To answer your question, as to what I understand, there really isn't a ratio or rule of thumb even for weight to draw to length. There are a lot of variables that can affect those measurements. The bid one that comes to mind is the type of wood, since each type of wood has its own compression and elasticity properties. I'm also not sure how you could have such a ratio because it doesn't take into account limb thickness, width or profile. You change any one factor and it can affect the others.
However, there are often plans available to give you a good staring point depending upon what type of bow and what type of wood you want to use.
I have not used yew, but from what I have read they usually are long and 'D' profile... 58" sounds short.
-
Generally with a rigid riser the length of the riser plus double the draw length so in your case 61" plus say 10" . On a bendy double your draw length these are generally accepted guidlines but nothing is hard and fast
-
I don't think bows need to be anywhere near as long as people are suggesting to reach 30 plus inches but they do need to be over 58". ;)
-
Ok thanks guys . I primarily use yew as it is readily avalible! And 58" is too short? I was hoping for a shorter bow to take hunting as it is usually fairly dense brush and it would be easier to manoeuvre around. I have one in the works now which is 70" ntn but seems very long to be packing in the bush.? I will start a new topic this evening with some pics!
-
you can make a 60 inch bow if you sinew back it,,and draw to 30 inches,,
if you want a shorter bow,, just make one and learn to shoot it with a shorter draw,,
I find that a bow that will draw 24 inches will shoot pretty hard,, so you could go 48 inches sinew backed and get nice cast at the 24 inches for you brush bow,,,, yes you are right Pat,, with a bit more experience you can get your bows quite a bit shorter than general rule of thumb,, I feel like a good osage stave could go 60 inches bend in handle, 30 inch self bow, and with sinew backing even shorter,,but would take an eye for the stave and some experience making the short bow,, I have seen some guys go way shorter with added deflex etc,, a good rule of thumb that will yield high success, is double the draw plus 10 to 20%,,,we have been debating bout that for at least 30 years so nothing new here,, :)
-
I have taken a few bows in the 64" range rigid handle self bows about 50# and brought them out to 30 or 31 to see if I would get better cast for broadhead flight shooting. They worked out fine but I didn't gain any distance.
-
Depending on the wood, double your draw and add 10-20%. Jawge
-
I don't think bows need to be anywhere near as long as people are suggesting to reach 30 plus inches but they do need to be over 58". ;)
I realize a bow can be shorter pat but he asked for a rule of thumb and that was what i gave him
-
Brad and Jawge, you guys have both reported a friendly version of what I have read in several old sources: Twice the draw length plus 15%. The math works out the same, but you guys are more forgiving. :laugh:
Jim Davis
-
This one here is a yew short bow, backed with sinew and only 43.5" long,
http://www.primitivearcher.com/smf/index.php/topic,40103.0.html
-
how about
bow 2" at the widest, deflex, short recurve hooks, 53" ntn, little to no overall reflex, draw 30.5"? sinew or... bamboo backed?
61" D bow with a little asymmetry?
-
This one here is a yew short bow, backed with sinew and only 43.5" long,
http://www.primitivearcher.com/smf/index.php/topic,40103.0.html
You missed the draw length. never mind the sinew.
-
how about
bow 2" at the widest, deflex, short recurve hooks, 53" ntn, little to no overall reflex, draw 30.5"? sinew or... bamboo backed?
61" D bow with a little asymmetry?
That gives you a 27-28" max draw and prolly would stack to high heaven and that's bendy handle
-
I don't think bows need to be anywhere near as long as people are suggesting to reach 30 plus inches but they do need to be over 58". ;)
I realize a bow can be shorter pat but he asked for a rule of thumb and that was what i gave him
I know but having shot his 58" for a year before breaking it in the cold it seems he could think about shorter than the rule of thumb. There does seem to be some sort of twilight zone for people between 28 inch draws and over. Nobody bats an eye at the bows on here 62" -64" drawing 28' but everyone seems to want to add nearly a foot to go beyond that.
-
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?
-
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.
-
Jim, I don't like short bows ( I like smooth drawing bows) so I build in a little more length.
Also, perfect staves can be shorter.
The presence of knots, twists, etc mean a little more length might be justified.
Jawge
-
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 😉
-
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.
-
Simplest approx' ratio is 2:1 to give a minimum bow length (wooden bow).
BUT that's for good wood, well designed made by a top level bowyer.
Del
-
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.
-
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.
Sheeesh... you can do anything with glass or carbon, (spits on floor) they are relatively unbreakable and have no relevance at all to wooden bows.
You can take any old glass bow and overdraw it by 50%...
Shouldn't even be talking about 'em on this board.... (hacks up hairball onto floor) :laugh:
Del
-
I'm with Del, thread is getting off track. Back to OP about selfbows.
I am still learning, only experience is with Osage, but like the starting point of 2x draw length +10%.
My shortest has been 63"ntn, 1-1/2" at fades,straight taper to 1/2" at tips,with draw length of 28".
Most of others have been 66" to 68". Not sure I can tell any performance difference between them. All of them around 50# draw weight.
-
I have a 48" hornbow that will pull 34" all day long. Deep string grooves and a lot of recurve. Skinny little thing too. A 72" bow will pull 36" if you tiller it right. I have another all hickory at about 64" with static recurves and deflex I built that'll do 36" as well.
Nobody told me that rule, so I simply made what I needed from what I had. I will say my hickory was perfect though. My tiller may not be, but at least my wood was.
-
Edward, true but we are talking about selfbows.
Jawge
-
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
-
hi guys sorry for the delay this is the bow that blew up!!
-
more pics the day i finished it.
-
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.*
-
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!!!
-
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.
-
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?
-
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.
-
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
-
more pics the day i finished it.
looks like it doesn't bend enough in the outer limbs?..
-
more pics the day i finished it.
You can't be drawing rhat 25"
-
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?
-
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
-
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
-
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.
-
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,,
-
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. :'(
-
For a bendy handle bow I like a minimum of 2x the draw length and for a stiff handled bow I like each limb to equal the draw length. It's possible to go shorter but I don't find it advantageous as much as an exercise in what is possible. If you like a short bow with a longer draw and high weight I think the key is more width and designing for more bend in the inner limb or handle. The width will aid in draw weight and by getting the limbs moving more in the inner limb stack will be reduced since string angle will be more advantageous. But I think the bottom line is try and go as long as you're comfortable with.
-
That does create some very unwieldy bows if you have a long draw-and the longer it is the worse it is. I can draw 42" with a yumi and mitsugake so these numbers make a massive bow if I use your double for bendy handle. For the same value I can make a Manchu style with 12" siyahs and achieve the same draw in a 70" ntn bow. The handle barely moves on that Manchu bow, too.
You guys are making me want to make one now.
-
That does create some very unwieldy bows if you have a long draw-and the longer it is the worse it is. I can draw 42" with a yumi and mitsugake so these numbers make a massive bow if I use your double for bendy handle. For the same value I can make a Manchu style with 12" siyahs and achieve the same draw in a 70" ntn bow. The handle barely moves on that Manchu bow, too.
You guys are making me want to make one now.
well both of those are designed for longer draws, a yuml is a longer bow and they are both backed wasn't the op about selfbows
-
That does create some very unwieldy bows if you have a long draw-and the longer it is the worse it is. I can draw 42" with a yumi and mitsugake so these numbers make a massive bow if I use your double for bendy handle. For the same value I can make a Manchu style with 12" siyahs and achieve the same draw in a 70" ntn bow. The handle barely moves on that Manchu bow, too.
You guys are making me want to make one now.
how long is the yumi?
lol it seems like bamboo can take more than most woods..
-
Bamboo isn't a wood
-
Hi guys yes sorry in that pic I am probly not bending 25" I couldn't find pics after that. I chopped 5" off each end and re tillers because of the lower limb hinge. But thank you guys for all the input. I realize I was pushing limits with 58" for 30" draw I'll try a few at 66-62"