Primitive Archer
Main Discussion Area => Bows => Topic started by: bow101 on June 30, 2016, 01:49:25 pm
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I place the arrow pass or shelf always 1 1/4" above center. Would it be better if the Bottom limb was longer or shorter, for shooting 3 under. I know I have read this one before somewhere. ???
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I don't know about limb length but positive tiller is needed for 3 under
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Only answer I can give is that I've seen plenty of 3 under bows that developed weak bottom limbs relatively quickly. I cant say the same for split finger bows, I've seen very few move. Maybe more important than limb length is tiller, as bub pointed out.
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I hear ya, so make the positive tiller about 1/4"...? I have seen a few bows on here that have unequal length limbs, was wondering why..?
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One of my sweetest bows was made on the fly at a festival with no real measurements. It was just tillered to shoot, the next week I tuned it up and finished it... lovely bow, only about 35# but fast, no set and sweet as a nut.
I never really looked hard at it until one day I wanted to make a slightly heavier scaled up version.
It turned out the lower working limb was 3" longer than the upper!
The conclusion?... It doesn't matter a tinkers cuss... it all about how it's tillered.
There's a lot to be said for having the working limbs the same length, and it's up to you how much stuff you have in-between 'em :laugh:
Del
BTW, I made the scaled up version with the working limbs identical length and that's a great bow too.
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The bows that balance best throughout the entire draw are those whose longitudinal center, string fulcrum, and dynamic balance point all line up. This is achieved by way of design(laying out bow center to suit the shooter's fulcrum) and balancing relative limb strength through tillering. When accomplished, there is no shifting from the static balance point(where it balances at brace) to the dynamic balance point at full draw. These are the sweetest drawing and shooting bows, and are quite inherently tuned... and this can be predictably done.
An asymmetrical bow exactly as you described, with the shelf 1 1/4" above bow center is a perfect layout for many 3 under shooters... assuming a 4" handle and average size hands applying even pressure because the string fulcrum is also at the 1 1/4" mark. The limbs then, if tillered/timed so the arrow nock comes straight back, will be harmonized while showing an even tiller as a result, and putting the dynamic fulcrum as well, at the 1 1/4" mark.... generally speaking.
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I have always felt the arrow should come straight back if drawn where the arrow mounts on the string but not necessarily when drawn. Regardless of how you draw the bow the bow will always return with the arrow holding the string back. It forgets all about how you drew it.
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bow101....Many good points made here.....Assuming your talking about durability then accuracy gets touched on here too.Tillering is the key here I think.Making bows over time will reveal this.I have always been pleased with how a bow feels and shoots when on the tillering tree while pulling the bow to full draw the point at where my hook of my poundage tester is the hook on the string travels in a straight line downward.That point is always close to where my fingers will pull when drawing and assume the arrow nock point will go in a straight line too right back to where I started drawing.The tips of the bow travel exactly even across from each other then every time.
My arrow passes are 1.5 to 1.75 above center of handle more so yet than yours but I don't really think it'll be much different.To me the bow shoots good at even, 1/8' or 1/4" positive tiller then with even length limbs.That's just shooting it 2 fingers under and one over but my one over is mostly just along for the ride.The two below do all the work.
If I shot 3 fingers under myself I would make the top limb longer.How much needs to be experimented with.With yours I'd try 1.25" longer.Just my two cents worth.I don't shoot 3 fingers under because sometimes an arrow nock fits too loose for me to trust[self nocks] and dry firing are no good for a bow......lol.
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I'm curious about people claiming to have the lower limb a little stiff when shooting 3 under.
I get the opposite results for some reason. I set the center of the bow as the pressure point on my hand. The arrow pass as close to that as I can get it, maybe 1" above center.
Even tiller and knock point usually shoots best square to the string. 3 finger under release. Anchor with the middle finger in the corner of my mouth, putting the arrow right below the eye.
I've had the top limb get weak after shooting a few 1oo arrows and required re tillering the bottom to get it back to even. Never had the bottom weaken.
Could the bottom limb be weakened from gripping and healing the bow with a high anchor.
Just trying to understand why, not trying to get off topic.
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The bottom limb more often gets weaker over time on symmetrical bows that are tillered positive, but it can happen sometimes on asymmetrical bows too. Depends on how far we pushed its limits, and how well it's tillered. A bow whose bottom limb gets weaker for no other good reason is trying to show us that relative limb balance is off.
Emmet, the 'relative' part of limb balance is indeed relative to the shooter's idioms, like healing the grip... among lots of other things. When a bow's limbs are fine throughout tillering, but then one of them gets weaker the more we shoot it, we're probably shooting it differently than we tillered it for. For instance, I see a lot of folks tiller symmetrical bows by pulling them at the center of the handle, and then when they shoot them, the pull the string 2" higher. That's a huge difference and can make the bottom limb lose strength over time.
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I don't think having an 'ideal' limb length ratio is anywhere near as important as having the correct tiller for whatever design/ratios you use.
The Japanese were apparently not to worried about keeping things even, it worked out pretty well for them.
(http://i116.photobucket.com/albums/o6/ryder85/Mobile%20Uploads/Kazuhisa-Sensei-Japan-Matador-SEO.jpg) (http://s116.photobucket.com/user/ryder85/media/Mobile%20Uploads/Kazuhisa-Sensei-Japan-Matador-SEO.jpg.html)
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The bottom limb more often gets weaker over time on symmetrical bows that are tillered positive, but it can happen sometimes on asymmetrical bows too. Depends on how far we pushed its limits, and how well it's tillered. A bow whose bottom limb gets weaker for no other good reason is trying to show us that relative limb balance is off.
Emmet, the 'relative' part of limb balance is indeed relative to the shooter's idioms, like healing the grip... among lots of other things. When a bow's limbs are fine throughout tillering, but then one of them gets weaker the more we shoot it, we're probably shooting it differently than we tillered it for. For instance, I see a lot of folks tiller symmetrical bows by pulling them at the center of the handle, and then when they shoot them, the pull the string 2" higher. That's a huge difference and can make the bottom limb lose strength over time.
Why would you tiller a bow based on how you pull it? We let go of the string when we shoot it so it should be tillered for wear the arrow sits, it instantly forgets where you lulled it.
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They weren't worried about keeping them even, as in equal length, but the great asymmetry means they have to concern themselves with other ways to achieve limb harmony, or suffer the same consequences we do. And like our bows, some Yumis are designed and/or tillered better or worse than others.
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Steve, with all due respect, we've had this discussion many times and I've told you each time why I don't believe your arrow theory. You'll have to kick that off with some proof one of these days ;)
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bow101....Many good points made here.....Assuming your talking about durability then accuracy gets touched on here too.Tillering is the key here I think.Making bows over time will reveal this.I have always been pleased with how a bow feels and shoots when on the tillering tree while pulling the bow to full draw the point at where my hook of my poundage tester is the hook on the string travels in a straight line downward.That point is always close to where my fingers will pull when drawing and assume the arrow nock point will go in a straight line too right back to where I started drawing.The tips of the bow travel exactly even across from each other then every time.
My arrow passes are 1.5 to 1.75 above center of handle more so yet than yours but I don't really think it'll be much different.To me the bow shoots good at even, 1/8' or 1/4" positive tiller then with even length limbs.That's just shooting it 2 fingers under and one over but my one over is mostly just along for the ride.The two below do all the work.
If I shot 3 fingers under myself I would make the top limb longer.How much needs to be experimented with.With yours I'd try 1.25" longer.Just my two cents worth.I don't shoot 3 fingers under because sometimes an arrow nock fits too loose for me to trust[self nocks] and dry firing are no good for a bow......lol.
A lot of good points no doubt. I have been shooting 3 under now for about 3 months and accuracy has improved, shooting split is off and on.
"I don't shoot 3 fingers under because sometimes an arrow nock fits too loose for me to trust[self nocks] and dry firing are no good for a bow......lol. " Tighten the nock fit.
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I am kind of teasing you here because I argue this with a lot of guys. If you look at the big factory manufacturers they don't tiller different for 3 under. Most guys I know tiller a bow to look even at full draw and show the arrow level with the arrow shelf or top of hand so you certainly are not alone. But it has just never made any sense to me. If the string remained in the same position when you released it you would have a big loose kink in the string. The bow has to follow the path of the most resistance which is the arrow. I actually tiller mine right below the arrow and I normally come out about 1/8 positive tiller which is about the same as everyone else so it doesn't seem to make a lot of difference. Just kind of fun to argue.
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Usually my arrow rests are around 2" above the center of bow, I've never worried about length of the limbs, I just keep them the same length. My main bow that has been shot thousands and thousands of times has no signs of one limb gaining more sting follow, both limbs have the same amount of set as when I made it.
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Steve the factory bow company's may not but if you order a custom bow they want to know if you shoot split or 3 under. I once saw G.Fred do a demo on 3 under versus split with a light weight Big Horn bow.
It was tillered for split, it looked very even and good tiller at full draw, then he pulled it back 3 under and the bottom limb bent way more, I think it matters and always tiller my bottom limb for someone shooting 3 under stiffer. I usually only make even limb bow but for a 3 under shooter top limb longer wouldn't a bad thing I don't believe. :)
Pappy
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Steve the factory bow company's may not but if you order a custom bow they want to know if you shoot split or 3 under. I once saw G.Fred do a demo on 3 under versus split with a light weight Big Horn bow.
It was tillered for split, it looked very even and good tiller at full draw, then he pulled it back 3 under and the bottom limb bent way more, I think it matters and always tiller my bottom limb for someone shooting 3 under stiffer. I usually only make even limb bow but for a 3 under shooter top limb longer wouldn't a bad thing I don't believe. :)
Pappy
Pappy, you made my point for me, when he pulled the bow the tiller went off. When he shot the bow the tiller went back to normal because he no longer had his fingers on the string. It is a big nyth! Of course the tiller will go off when you pull it 3" lower, but when you shoot the bow it doesn't go back the same way you pull it.
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Yep, I was always curious about how a bow shot with people that string walk. I have watched a few in the last few years and it seems the father the target the better arrow flight they got because they were closer to the nock point. I am trying to get what you are saying wrapped up in my head, :-\ I am pretty dense so it may take a while. ;) :) :)
Pappy
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bow101....I do tighten the nock fit but still shoot mediterranean style.Super glue build up or heat and pressure bending are my solutions for that.Over time and being a favorite arrow they can wear a bit.That's just the way it is and it's the way I was shown to shoot by watching and adopted that way.Did'nt mean it was the only way to shoot.I do shoot only self nocks though.No plastic.Anyway that's for the arrow section really and has nothing to do with your question and an irrelevant point made if things are up to snuff like yours....sorry.
I see that your question was two fold then.Durability and accuracy.I know if I shoot consistently every day for a month my accuracy improves too.Shooting a bow involves so many fine points that the only way to get half a$$ accurate consistently is from muscle and mind memory seems for me.
While making and shooting these self bows the bows will reveal different durability wear like set in one limb or another.Should'nt if tillered the same but does occasionally.That could be just bad tillering.So I'm of a belief that it's still all about how well it's tillered no matter where you shoot from on the string for both durability and accuracy.Making your top limb longer for three under.I'll put my time into making it that way if it was me.Each to his own I say.
It was explained before here why the bottom limb gets more stress.Maybe someone can remind us.It'll probably say somewhere in one of the TBB books but don't know where.
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Yep, I was always curious about how a bow shot with people that string walk. I have watched a few in the last few years and it seems the father the target the better arrow flight they got because they were closer to the nock point. I am trying to get what you are saying wrapped up in my head, :-\ I am pretty dense so it may take a while. ;) :) :)
Pappy
Pappy you are in good company, I don't think I have found anyone that agrees with me on this. Once you tune your bow it doesn't seem to make all that much difference anyway.
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If the bow's tiller at full draw, what some call relative limb strength, is disproportionate, the stronger acting limb WILL pull the string fulcrum, nock point, and arrow nock toward itself, relative to the shelf. By the time the bow is back at rest, at brace height, it WILL have returned to where it started. Where you and I differ on this Steve, is that you believe it returns AFTER the arrow is gone because the arrow somehow has the ability to completely overpower the strength disparity between the limbs... while myself, I believe the nock point begins to return to its original position as soon as we release the string, because releasing the string allows the power we stored in the limbs (disporoportionately in this case) to affect the arrow. If the nock point is returning to its original position relative to the shelf as the string falls, as I suspect it does, it's taking the arrow nock with it(unless the string slips through nock) until it leaves the string... which can inflict the arrow with a porpoising action. This is why some bows are difficult to tune and folks have to move the nock points to adjust relative limb balance to correct arrow flight.
If what YOU say is true, there would never be such tuning or arrow flight issues, or handshock, etc. because the arrow would cause the tiller to go back to "normal" the instant we let go of the string. That's simply not what I've found to be the case.
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I pretty much agree with what you are saying, I don't really think it goes back instantly but I think it goes back within a few inches of the power stroke. I would like to see a slow motion video focusing on the knock point and the string.
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Yeah, me too.... video of the nock point and it's relationship to the shelf/square to the handle, etc as the bow was drawn and shot.
I wish I had a lot more high tech equipment as I work on these primitive bows :)
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Try this, although I think Mike Loades nock point is out
https://www.youtube.com/watch?v=ir5GKAQG14g
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Why would you tiller a bow based on how you pull it? We let go of the string when we shoot it so it should be tillered for wear the arrow sits, it instantly forgets where you lulled it.
Try "gap shooting"? Though that may simply change the angle of the arrow
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Didn't somebody post a whole bunch of super slow MO videos of bows being shot? With bad tiller, nock high, etc?
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Tuomo, his videos are here
https://www.youtube.com/channel/UCmVczwYUfq6sQQjCmKd2q5Q