Author Topic: Bow tips when tillering  (Read 584 times)

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Offline ShorterJ

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Bow tips when tillering
« on: February 22, 2021, 09:00:49 pm »
Iím working on my first bow and have probably already messed up trying to figure out the whole tiller concept.  Anyways, my bow tips are naturally uneven when unbraced. One is sort of recurved out and the other is deflexed in. My question is shouldnít each tip come down an equal amount instead of trying to get them to come to the same point? This would make one limb look like itís bending more when in reality they are bending the same amount right? Iíll attach pictures.  I know one of my limbs is still stiffer, but when I get it tillered out shouldnít the tips still be uneven? I hope this makes sense. Thanks for any help!

Offline willie

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Re: Bow tips when tillering
« Reply #1 on: February 22, 2021, 09:15:03 pm »
my bow tips are naturally uneven when unbraced. One is sort of recurved out and the other is deflexed in. My question is shouldnít each tip come down an equal amount instead of trying to get them to come to the same point?

yes, in theory that would be what happens. to measure the deflections separately, your bow would be needed to be clamped in a vice or such. measuring this way will work at the beginning of the tillering process, but once you have the limbs bending the "same", what will happen when you are drawing with a light grip on the bow?

The handle will cant slightly in your hand. some folks find this disconcerting and see no apparent way to estimate same bending in both limbs as you get closer to full draw.

just from your braced and unbraced pics, I will guess your limbs are both bending too much mid limb? How far have you drawn the bow at this point?

Offline ShorterJ

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Re: Bow tips when tillering
« Reply #2 on: February 22, 2021, 10:04:47 pm »
Iíve drawn it maybe a foot plus or minus a few inches, but just for a short amount of time. I fear premature set due to poor tiller, so I havenít drawn it very far. Iím having trouble seeing which part of the limb is too weak or strong. I guess I donít have an eye for it yet.

Offline willie

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Re: Bow tips when tillering
« Reply #3 on: February 22, 2021, 11:17:49 pm »
just pull it some until the uneveness is apparent to you, and snap a pic. guys here will be more responsive with help if there is something to look at.


As it's your first bow, getting an "eye for it" is what it's all about.


Offline Del the cat

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Re: Bow tips when tillering
« Reply #4 on: February 23, 2021, 06:28:26 am »
A bow is not symmetrical because you can't hold it and shoot the arrow from dead centre!
Have a look at this post from my blog... it's a bit wordy, but it explains some stuff.
You may want to read the last paragrah, and look at the bottom pic first. :)
https://bowyersdiary.blogspot.com/2013/03/tillering-symmetry.html
If have a look at a bow when you hold it down low and just take up the tension ... you'll see it isn't sitting square in the hand, it pivots as you apply more force.
It show up nicely in this short video:-
https://www.youtube.com/watch?v=ZMWJ6Ycy_B8
Del
« Last Edit: February 23, 2021, 06:36:47 am by Del the cat »
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Online Dances with squirrels

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Re: Bow tips when tillering
« Reply #5 on: February 23, 2021, 10:05:26 am »
Tillering should accomplish a couple of things. Generally, it should make the limbs flex evenly along their lengths. And, IMO, tillering should adjust their strengths so they travel the same distance when held as the archer will hold it. At the very least, we should pull the string from where our string hand will be placed.

Bows can be designed and tillered so they won't tip in the hand.

Oddly shaped limbs should not be tillered to bend in perfect arcs like a perfectly straight limbed bow would. At full draw they could/should be reminiscent of their original oddities... unless they were quite minor in which case they can be nearly impossible to see at full draw. And they should not be tillered to come down to the same point on the the wall, or same distance behind the handle..... unless they were in the same plane to begin with. I never use that as a gauge. Even on limbs that ARE the same. Instead, I try to hold the bow on the tree similar to how I'll hold it, mimic the placement of my fulcrums, then seek balance as it's drawn so it doesn't tip on the tree. If it doesn't tip on the tree, it doesn't tip on me.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline Del the cat

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Re: Bow tips when tillering
« Reply #6 on: February 23, 2021, 11:03:07 am »
...Bows can be designed and tillered so they won't tip in the hand...
IMO, yes, BUT only is if you pull the sting exactly in line with your grip (3 fingers under) and then nock the arrow about 1/2" above that.
With a Mediterranean loose you are pulling the string above where it is supported in the hand and this will cause it to tilt when force is first applied ... unless it is gripped very hard to prevent it pivoting.
If you don't believe this, just balance a length of 1x1 at it's centre and then add some weights 1" to one side of the centre... it will tip.
Del
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Offline ShorterJ

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Re: Bow tips when tillering
« Reply #7 on: February 23, 2021, 12:03:33 pm »
Thank you all so much for the input! This is all very valuable information to me.

Online Dances with squirrels

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Re: Bow tips when tillering
« Reply #8 on: February 23, 2021, 01:48:09 pm »
I shoot Mediterranean with a loose grip and my bows don't tip in my hand. There are other factors.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline Del the cat

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Re: Bow tips when tillering
« Reply #9 on: February 23, 2021, 02:10:30 pm »
I shoot Mediterranean with a loose grip and my bows don't tip in my hand. There are other factors.
If you look down at the bow as you first put tension on the string... are you sure it is still pulling straight?
Have you looked?
Do you hold the bow down low in front of you when you first touch the string so that you can see this?
If you have the bow up at arms length when you first hold the string you won't be able to see it unless someone videos it.
Any how... I have no wish to argue... if you can't see it ... then you can't see it.
We all do stuff our own way.
Del
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Offline bownarra

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Re: Bow tips when tillering
« Reply #10 on: February 23, 2021, 03:17:40 pm »
Dances is right and so is Del. Its just they are saying different things ;)
:)  My bows don't tilt (during the draw) either though....and I certainly don't shoot 3 under :)

As for the original question yes you are correct in your thinking regarding limb movement. My suggestion to help make things a whole lot easier for you would be to use a heatgun to heat the deflexed areas straight. Basically get your tips on the same plane. Tillering uneven limbs is a royal pain and the deflexed tip ain't great for performance.

Online Dances with squirrels

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Re: Bow tips when tillering
« Reply #11 on: February 23, 2021, 05:39:44 pm »
Del, I know exactly what you're talking about. I'm very familiar with the tilt, it's physics, and the sliding fulcrum that bowyers 'should' navigate when the bow hand and string hand fulcrums part ways, and I work to minimize it or eliminate it from beginning to end of the bow making process. It's one of the most important aspects of my bow making and has been for a long time.

The way I hold the bow, my bow hand fulcrum is above handle center, which is where I place bow center. String fulcrum is slightly above them, so yes, initially on the tree with a single hard pivot point placed where the full draw balance point will be when I get there, with the lightest pressure it will begin to tilt, but very, VERY quickly balances. I make sure of it. It's so slight that in my hand, just the give of the flesh eliminates it, even with an open hand. There's no visible tilt. But I've become hypersensitive to it, so I can still feel that minimal fulcrum shift 'inside' my hand. I just went and grabbed a bamboo backed osage bow, strung it, nocked an arrow, and played with the early draw. No tilt. Sorry brother. Took me many years to get them that way. But that's where they're at.

Trust me, I can reveal the slightest bit of it with ease, and with bows where it happens... I see it tilt in my hand, I feel it in my hand, and I see it on my tillering tree. Some bows tilt so harshly in the early draw I think this is why some guys hold them stationary and pull the string in line with the center of the grip. They refuse to balance their bows by pulling the string where their hand will, or on tillering trees that allow them to tilt. The harsh initial tilt freaks them out, confuses them, panics them, and they fall back to 'just tiller em all slightly positive'.

I don't want to argue either, but healthy respectful debate can be informative for all. I'm just saying there are other factors that we can control that can reduce or eliminate it. We don't have to grip it tight to stop it, unless we want to make bows that way or prefer shoot that way. Though I don't know why anyone would. But even when it happens, most people don't see the tilt or feel it as a negative thing, they don't design their bows to reduce it, tiller to reduce it, they just ignore it, or don't know or care, and like it that way... until it's bad enough the bow complains or the arrows don't fly so good.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline Del the cat

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Re: Bow tips when tillering
« Reply #12 on: February 23, 2021, 06:34:16 pm »
@ Dances with squirrels:-
Nice post :)
Del
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Online Dances with squirrels

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Re: Bow tips when tillering
« Reply #13 on: February 23, 2021, 08:31:41 pm »
Thank you sir.

Happy yew shavin' to you.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline George Tsoukalas

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Re: Bow tips when tillering
« Reply #14 on: February 23, 2021, 10:02:02 pm »
My bow tips bend 2-3 inches so different  so having one reflexed a little and one deflexed is not that crucial to me.

Jawge
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