Primitive Archer
Main Discussion Area => Bows => Topic started by: redhillwoods on January 06, 2021, 07:22:24 pm
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I generally make the top limb 1-2" longer than the bottom. I'm curious if this is normal practice with other folks. Also, l tiller the top limb an inch further down on the tillering tree. Do you do this also or bring both nocks the same distance down from the handle?
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I try to keep things a simple as possible and make matching limbs. Sometimes I make the lower limb a bit wider though.
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If I make it asymmetrical I usually make it a 1” difference between the limbs and give it a 1/8” positive tiller at brace. Seems to work well.
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If I make it asymmetrical I usually make it a 1” difference between the limbs and give it a 1/8” positive tiller at brace. Seems to work well.
That's the way :)
Asymmetrical bows carry much better.
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I’m making the handle 1” above and 3” below the center of the bow. This makes the lower limb shorter so I tiller it some 5 mm stiffer also.
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I usually make handle center 2 cm lower than bow center. I tiller tips to the same distance and I want to see a very slight handle turning towards the lower limb.. on tillering tree. It shows me that the lower limb is a bit stronger.
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I do practically none of the things mentioned so far. I don't want either limb to act stronger, or look stronger at brace, necessarily.
Usually I place the handle center 3/4" or 7/8" below bow center, because that balances the bow in my hand where I want while carrying it. Then I put it on the tillering tree, pull the string from where my string hand fulcrum will be, and balance the limbs. But I do this the exact same way regardless of degree of (a)symmetry.
There are two methods I use to balance the limbs. One holds the handle so the bow can NOT tilt in the tree. The other allows the bow to tilt freely, with no restriction. I have a vertical line drawn on the wall at the location of my string hand fulcrum. It is perpendicular to the handle, and if the limbs are balanced in strength relative to my holds, the hook on the string will perfectly follow the line down the wall. If however, the hook moves toward a limb, it's strong, so I weaken it until the hook follows the line. It's that simple. That is dynamic balance.
Every bow I make, regardless of limb shape differences, or differences in symmetry, or resulting brace heights(they differ), is equally balanced. Balanced by the same method. Balanced to my same fulcrums. Balanced to the same degree. Yet the tiller measurements often differ. That should cause many folks to start asking themselves some questions.
So, which ones would be balanced if I had made them all measure the same at brace? Any of them?
By using predetermined measurements, we are guessing. We're making a bow 'look' a certain way at brace and hoping it acts the way we want, rather than making it 'act' balanced in our hands while drawn. A bow's tiller measurements at brace height doesn't mean what folks think it does. Hardly, if ever.
For instance, a bow's bottom limb doesn't have to 'look stronger' at brace height in order for it to 'act stronger' while being drawn. Many bows with even tillers have stronger acting bottom limbs. Much depends on how the grip is held and bow center location.
You think by building limb strength to a predetermined measurement at brace, that you have the bow balanced for you? Ok great. Now place a free pivot point under the handle where you want your bow to balance in your hand during the draw, and pull it from your fulcrum on the string and see what happens. Odds are you'll be quite surprised... then maybe feel an urge to scratch yer head ;)
My thing is... why don't folks tiller their bows so they're NOT surprised. So they KNOW exactly where and how their bows balance, rather than guess, assume, or hope.
I don't know what the tiller measurements are going to be on the bow's I make, and I don't care. They are merely a result of balancing the bow... not a beacon for me, and nothing predictive. In fact, I usually don't even measure them anymore.
Last thing then I'll shut up... bow center location is a sizable factor in how the tiller profile will present itself after balancing. In other words, all else equal, 1/8" positive tiller on a symmetrical bow and 1/8" positive tiller on an asymmetrical bow means they will balance differently for the same shooter. Just some things to think about...
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Does the hook on the string mimic a hand drawing the bow? I've never seen a tiller tree with a top shaped like a palm and a hook mimicking a drawing hand.
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No Pat, but it doesn't have to. It mimics the fulcrum, or center of pressure. For me that's about 2/3 of the way down my middle finger. I use a nock point 3/8" above perpendicular to the shelf on all my bows, so it's easy enough to figure out where that hook should be placed.
The cradle doesn't have to mimic the bow hand exactly either. When limb strength is balanced while supporting the bow handle so it can't easily pivot, the dynamic balance point is somewhere within that supported area of the handle, and that degree of accuracy balances a bow pretty good in most hands. Many folks though would find their bows unbalanced even to this more general 'standard'. What would it hurt to try?
And then if we want to balance it better for our personal shooting idioms, or find out exactly where the dynamic fulcrum is, so we can use relative limb strength to coax it one way or the other under the hand while maintaining limb harmony, the bow should pivot freely to reveal that. Just my 2 cents.
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These days I make symmetrical bows so I can flip them around if I can't completely tune a bow for silence. Silence is golden.
Jawge
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I have never believed in balancing a bow to how it is drawn because when an arrow is shot we obviously let go of the string and at that point the limbs are only responding to the arrow holding them back. So My belief is that balancing the bow at the arrow nocking point works out better.
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Jeff is channeling Dean pretty well. He seems more sure though. Dean once wrote a lengthy article which essentially boiled down to him not really being sure what was going on.
A bow of slightly positive tiller feels perfect to me every time.
A bow that looks lopsided at brace but is tillered to follow a straight path exclusively feels lopsided the whole way back. Especially if that limb is the lower limb.
To me at least.
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As long as the bow shoots well I don’t care what it looks like or how it got there. ;D
I think it’s important to note for new builders that moving the center “x” inches makes the limbs “2x” difference in length. For example, moving the handle center 1” below the true center will make the difference between the limbs 2” all else being equal. I usually go 0.5” below center for a 1” difference as 2” seems extreme to me. A way to get around this is to make the fade lengths different.
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Noise comes from vibration. Vibration comes from limbs that aren't working in harmony.
I like them silent too. If I had to flip my bow around for it to better behave in any way, I'd surely reevaluate how I made it. Pfff, I constantly reevaluate how I make them anyway :)
Dynamically balanced bows are largely inherently tuned. No need to flip em, adjust tiller, or move the nock point around.
Guys say they make them symmetrical and tiller and balance them by drawing from the center because it's easier. Is it?
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Definitely easier. They just move the nock point a hair.
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What does positive tiller mean?
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My tiller tree comes to an apex, and the bow sits on a one eighth strip of leather on the bow's riser . 60 inch bow mark 30 inches to the middle. Stiff limb goes on the bottom. Measure up one ,and an eighth inch, and cut a radiused arrow shelf as close to center shot as I can ,and still be safe. Then cut a place for my thumb,and index finger on the grip. That is my left hand grip.Then adjust string nock to bare shaft arrow tune with a properly spined arrow, and you can tune the bow to the arrow with the depth of your arrow shelf. When the bow is finished measuring from the arrow rest the top limb is shorter than the bottom limb, but the bow is balanced through the draw cycle , and shoots the way it should by my standards.
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Pat, you obviously didn't understand Dean's article. No biggie. Most didn't. I sure didn't, at first.
I've been working my bows this way for over 20 years, and a while back decided to more deeply study and test bows and how tiller/balance affects things. My goal is to dispel myths, misunderstanding, confusion, and conflicting info that surrounds it, if only my own :) I may start a thread or write an article or webpage about it when I'm done, or maybe it'll all just be for my own peace of mind. We'll see. I do seem to encounter resistance when I address the topic in these forums. Maybe its my delivery. Lol
I have a long list of questions and theories to address throughout my testing, but if anyone here would like something rooted out... feel free to mention it and I'll try to address it.
I revisit Dean's article on occasion because I want to know if he was all wet, and so far from what I've seen, he's been right, and the deeper I dig, the more little truths jump out at me from his words... words that seemed almost cryptic to me the first time I read it. He told me once to do my own testing, and question everything and everyone, him too. That's what I'm doing. And trust me, I question myself and my own methods and results more than all others combined.
I think recently I've found some things that may help us all understand, but I have a lot of testing to do yet. This has already turned into something bigger than I thought it would be, but I'm going to keep chipping away at it for a while.
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I think you just interpreted it the way you wanted to. ;)
The article seemed more written to make people think and draw their own conclusions. I do think Dean was trying to say what you're trying to say but still not quite getting to the point.
People will probably want to see a slo mo video of your bow on the tree and a slo mo in the hand, as well as slo mo releases.
Otherwise you're basing it more on feel and what you think is happening.
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Does the hook on the string mimic a hand drawing the bow? I've never seen a tiller tree with a top shaped like a palm and a hook mimicking a drawing hand.
The clamp on the top of my tillering tree mimic the hand. This clamp can spin on bearings :)...Don't look at tiller :D :D...
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Hmmm, geeze, I have some equipment, but no slow mo video capability. Ok, I'll think about that. I do have an accelerometer to measure handshock and some load cells in the string to compare limb tensions.
I've been digesting bow making articles, books, websites, and such for some time trying to learn all I can, and it's weird how the subject is obviously avoided, or only mentioned in passing, or they get right to the brink of the good stuff and bail out, or use the opportunity to justify their own methods and theories, or divert to conventional wisdom. That's not what we need.
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Not much different than any goo glass recurve really. The center is usually center or just a tad higher than middle of bow. You build limbs and come in heavy on both limbs and shoot it in sanding limbs to time and reduce vibration.
Notice how the Ante and this Drake have very similar designs. Good recurve design is good recurve design.
Shawn~
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...Don't look at tiller :D :D...
It looks almost like the right outer limb bending more than the left? :D
Just kidding, nice bow. :)
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...Don't look at tiller :D :D...
It looks almost like the right outer limb bending more than the left? :D
Just kidding, nice bow. :)
:D :D It seems to me that left limb bends more from the center...
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Yeah, you got a sideways eyes the pic is taken on 30 degree angle. My limbs are spot on and in exact alignment. There she will sit for the near future.
HH~
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The bow Maitus posted, not yours.
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Any production glass recurve with an arrow shelf will have a shorter upper limb up to 2 inches when you measure from the shelf both ways, and one eighth of positive tiller, and I own some that have as much as one half inch positive tiller. Still shoot good with string nock adjustment. With no shelf I set the bow up on the tree the same way,and tiller.
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Quite a few people also make limbs equal length and have a slightly longer handle but that still amounts to a longer upper limb.
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The bow Maitus posted, not yours.
I didn't post a bow, I posted the tillering tree :D :D
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It is rare that I have made or shot a bow where I felt limb balance was a serious issue. Handshock is the thing that comes up periodically but is usually predictable and balance doesn’t seem to be the cause. Maybe for flight shooting and perfect arrow flight this is important but otherwise most bows will make meat whether you made sure it was “perfectly balanced” or not.
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http:/ /www.bowyersedge.com/organic.html
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I literally flipped and flipped in bed last night from 11:30 till 4:45 when my alarm went off not being able to sleep for trying to work out in my brain all of what has been discussed here. “Why one limb longer?” “How can I have the stiff handle designed like I want and still have limbs of equal length and perfect symmetry?” “Why would this even matter?” “Would it help?” “Why would it or wouldn’t it help?” “Does my design need help? My twisty-funky selfbow shoots far better than my 1,500$ Lam/glass bow and better than my tried and true Jeffery recurve, so is that all in my mind?”
Then I’d give that a rest and do the same thing with knapping issues I’m facing. Didn’t sleep a freaking wink!
Good to know that as a whole, this board is as confused as I was...I say was, because after reading this, I think I’d have a better chance solving a Rubix Cube than making sense of all the info bouncing around in my noggin.
I’m going to keep all this handy, dandy info in my brain, but I’m going to keep doing what I’m doing until the bows I’m making start feeling and/or performing in a way that forces me to change. Ie...I’m going to go with the KISS method.
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I have a long list of questions and theories to address throughout my testing, but if anyone here would like something rooted out... feel free to mention it and I'll try to address it.............
this has already turned into something bigger than I thought it would be, but I'm going to keep chipping away at it for a while.
exploring ideas as to how we could adjust tiller for dampness in the hand as we approach final draw length during the tillering seems intriguing.
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You build limbs and come in heavy on both limbs and shoot it in sanding limbs to time and reduce vibration.
Shawn~
Shawn,
when you feel vibration, how do you know where to sand the most?
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I start out with limbs the same length from center of bow unless for some reason the stave won't let me. I do like the balance carrying the bow with a little longer top limb but as for shooting I see no difference. :) I cradle the bow in the tiller tree to see where I want the arrow pass to be and also have a tab for the scale and pull rope to mimic 3 fingers. Lots of ways to skin a cat but this works for me. ;)
Pappy
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Your right pappy, and if it works it works.
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Depending how a guy is gonna shoot the bow 3 under or Split just a matter of how you set tiller and how much weight outter limb is carrying.
3 under Selfbow i leave bottom limb 1/4”-3/8ths for shooter. Lots of vibration pulling all that bottom limb. Split you go 1/4” to even tiller. Limb mass has a lot to do with vibration.
If you getting bad hand shock out of a selfbow something is way off!
Reason glass bow upper is shorter is only cuz you find center and shelf goes in 1” to 1 3/4” above center pivot why on glass bow you have engineer in if want 1/4” positive tiller ie ; thicker belly glass or belly lam or both, etc. with a selfbow you do it by leaving more wood or you can shorten bottom limb.
Of course if you only have back of hand holding you arrow from falling off you can do it whichever way you want. To me a bow without an American selfbow shelf is only 1/2 a bow. If im teaching a new person shooting form im sure as heck not doing it off the back of their hand.
Shawn~
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I cut a deep shelf in all of my self bows unless I am making a replica, but their are those that would call them shelf bows,and not self bows.