Author Topic: relative limb length  (Read 3682 times)

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Offline redhillwoods

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relative limb length
« on: January 06, 2021, 07:22:24 pm »
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?

Offline Digital Caveman

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Re: relative limb length
« Reply #1 on: January 06, 2021, 07:26:34 pm »
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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Offline RyanY

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Re: relative limb length
« Reply #2 on: January 06, 2021, 07:30:08 pm »
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.

bownarra

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Re: relative limb length
« Reply #3 on: January 07, 2021, 12:29:22 am »
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.

Offline Lehtis

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Re: relative limb length
« Reply #4 on: January 07, 2021, 12:43:41 am »
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.

Offline maitus

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Re: relative limb length
« Reply #5 on: January 07, 2021, 02:36:38 am »
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.
« Last Edit: January 07, 2021, 05:56:25 am by maitus »

Offline Dances with squirrels

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Re: relative limb length
« Reply #6 on: January 07, 2021, 05:57:46 am »
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...



Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline PatM

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Re: relative limb length
« Reply #7 on: January 07, 2021, 07:14:40 am »
   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.

Offline Dances with squirrels

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Re: relative limb length
« Reply #8 on: January 07, 2021, 08:08:10 am »
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.
Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline George Tsoukalas

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Re: relative limb length
« Reply #9 on: January 07, 2021, 08:11:55 am »
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.
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Offline Badger

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Re: relative limb length
« Reply #10 on: January 07, 2021, 08:26:10 am »
   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. 

Offline PatM

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Re: relative limb length
« Reply #11 on: January 07, 2021, 08:42:23 am »
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.

Offline RyanY

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Re: relative limb length
« Reply #12 on: January 07, 2021, 08:51:27 am »
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.

Offline Dances with squirrels

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Re: relative limb length
« Reply #13 on: January 07, 2021, 09:02:59 am »
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?

Straight wood may make a better bow, but crooked wood makes a better bowyer

Offline PatM

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Re: relative limb length
« Reply #14 on: January 07, 2021, 09:10:33 am »
Definitely easier.  They just move the nock point a hair.