Author Topic: Limb length design  (Read 10550 times)

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Offline Roy

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Limb length design
« on: April 16, 2013, 06:44:25 am »
How do you guys lay out your self bows or BBO bows, with equal limb length or with the bottom limb a little shorter. And if shorter by how much?

Offline DarkSoul

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Re: Limb length design
« Reply #1 on: April 16, 2013, 07:29:45 am »
Equal limb lengths make for easier tillering. I usually make both limbs the same length, but I don't worry if one limb ends up ½" shorter. With nice and even fades, it's difficult to accurately measure where the limbs start anyway. Sometimes I lay out one limb to be one inch shorter, but that only happens when I have a defect in the wood that requires uneven limb lengths.
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Offline Roy

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Re: Limb length design
« Reply #2 on: April 16, 2013, 07:55:51 am »
Do you pull the bow on the tree from the center of the handle or more to the right where your drawing hand will be on the bow string?

Offline Del the cat

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Re: Limb length design
« Reply #3 on: April 16, 2013, 08:04:41 am »
I always put a bow on the tree so it's supported where my hand will support it, and I pull on the string from where my fingers will be.
The bow is supported on a curved rubber faced block so it is free to pivot and rock like it would in your hand.
It can look weird as it is quite tilted towards the top limb at low draw weights.
IMO doing anything else, or clamping the bow to the tree can give a false impression.
Del
Health warning, these posts may contain traces of nut.

Offline BowEd

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Re: Limb length design
« Reply #4 on: April 16, 2013, 08:24:05 am »
I pull right from the center of handle on tree tillering.Limb length even or close to it with slight positive tiller.Done it both ways [limbs different length and pulling at the knock point on tree]and don't see any diff.I go by feel shooting and if it feels right it's right to me.Bows stay in tiller.
BowEd
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Ed

Offline Roy

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Re: Limb length design
« Reply #5 on: April 16, 2013, 09:09:27 am »
I pull from where my middle finger will be on the bow string when an arrow is nocked on the string. I have tried pulling from the center and more to the right and it does seem to make a huge difference in how the limbs bend down on the tree when pulling more to the right. I've been round and round with this with a buddy that makes awesome bows, and I believe what he says about pulling from where your drawing hand is going to be on the bow string is the proper way to tiller a bow.

Offline lesken2011

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Re: Limb length design
« Reply #6 on: April 16, 2013, 09:45:38 am »
Given that I am still a novice at this, having made about 2 dozen bows, so far, I have elected to use the kiss approach to this point. (keep it simple, stupid) I keep the bow limbs even and center the bow on the tree. This makes it easier for me to take photos and flip the image of one limb for comparison to the other. I have also been focusing primarily on circular bends. As I get more experience, I will move into the more intricate tillering methods. What yall said about bow and string positioning makes sense, though, and I am sure I will be gravitating to that method to improve my tillers in the future.
For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast.

Ephesians 2:8-9

Kenny from Mississippi, USA

Offline H Rhodes

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Re: Limb length design
« Reply #7 on: April 16, 2013, 05:44:07 pm »
I watched a fellow lay out a bow and his method made sense to me.  He stretched his arms out as wide as they would go and lifted the stave to his nose and said "Yep, there's the middle."  He drew a line on the belly at that point where his sweaty nose had left a little round spot.  He grabbed the middle of the stave and made a special point of putting his middle finger right on top of that line he had drawn.  He marked either side of the hand holding the stave and said "Yep, there's the handle."   Then he measured off equal limb length from the ends of the handle.  His bows look great.  It made me think that  there is more than one right way to do this stuff.   
« Last Edit: April 16, 2013, 05:57:47 pm by hrhodes »
Howard
Gautier, Mississippi

Offline Onebowonder

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Re: Limb length design
« Reply #8 on: April 16, 2013, 06:28:28 pm »
<snip>It made me think that  there is more than one right way to do this stuff.
Now that's just CRAZY TALK!  How can there possibly be more than one way to do it right???  I mean look at the exact uniformity of all bows ever found in all archeological sites!  Surely if all those ancient guys all did it exactly the same way, ...then we should too!  ::) :o ;)

OneBow
« Last Edit: April 16, 2013, 07:45:04 pm by Onebowonder »

Offline Roy

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Re: Limb length design
« Reply #9 on: April 16, 2013, 07:04:55 pm »
LOL, I'll have to try that method:)

Offline H Rhodes

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Re: Limb length design
« Reply #10 on: April 16, 2013, 07:49:14 pm »
I watched him do it and thought about how long I spend laying one out  with a tape measure and combination square and couldn't help but laugh.  My next bow I did it the same way, right down to "the sweaty nose move" and found that it worked pretty good.    Sweat on the nose is easy to come by in mid-April Alabama workshops when debarking winter cut hickory! ;)
Howard
Gautier, Mississippi

Offline JackCrafty

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Re: Limb length design
« Reply #11 on: April 17, 2013, 01:24:22 am »
Most of my bows have symmetrical limbs with the center of the bow placed on the center of my tillering tree.  I don't put it on the tree until I floor tiller it and the bow balances on the center point.  If the handle area has a riser, I align the center of the riser on the center of the bow.  I then tiller the bow with both limbs bending the same.

The only times I don't do it this way is when I'm building a historical reproduction that doesn't follow the above pattern.   :)
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Offline hedgeapple

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Re: Limb length design
« Reply #12 on: April 17, 2013, 01:57:24 am »
Roy, that's the kind of question you can only answer yourself after you've built several bows.  Historically, bows have been built every way imaginable.  And to be honest, I asked a similar question not long ago.  I had been building bows center line plus an inch to 1 1/2  above for the arrow past.  That made the upper limb longer. But, that made the lower limb bend more and played with my eyes tillering them.  Recently, I built a hickory bow the with the same design, BUT I extended the arrow past so that both working limb were the same length.  I made that bow for a newby and make a cut in arrow rest.  It shot very well.

I was recently gifted a bow by Blackhawk that was true center of the handle., stift handle bow.  I love it.  I shoot it better than any bow I've made so far: perface I suck at accuracy, anyhow.

Short answer:  Make several styles and see what you like best.
Dave   Richmond, KY
26" draw

Offline Elderic

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Re: Limb length design
« Reply #13 on: April 17, 2013, 02:13:31 am »
I have been reading and wondering about limb length myself. I haven't started my first bow yet, so I may be overthinking it. For example, if you layout the bow with 1 inch above and 3 below center, this ends up leaving the lower limb shorter (I think). But then if you add extra length to the lower limb, won't this change your center point?

Offline Hrothgar

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Re: Limb length design
« Reply #14 on: April 17, 2013, 08:16:36 am »
This is an interesting topic, especially for someone just beginning. There are several factors that go into play when you start trying to figure out limb length/handle placement. Its also a good idea to use a pencil and paper, and have a bottle of aspirin nearby. If you are going to build a bow with a long riser and cut-in arrow shelf then using the method of 1 1/2" above and 2 1/2" below center is theoretically accurate, and will yield a longer top limb, which crates the need for a stronger shorter limb. All this is good advice for a longer bow or an ELB. However, for the sake of ease and simplicity and choosing to 'shoot off the knuckle'--which it seems many of us eventually gravitate to, then doing as Del and DarkSoul have said: center the bow on the tillering tree at the spot where your hand will grip the bow, this will pretty much ensure that the finished bow will be bending evenly out of your hand at full draw. But as Roy said, the arrow rest will still be an inch or so off-center (this factor is slightly adjusted when/if the string is pulled using a 3 finger draw, with 2 fingers under the arrow and 1 on top. This is also the reason why its a good idea to pull the bow an inch further on the tillering tree than what is to be the shooting draw length; since on the tillering tree the string is only going around a nail or peg, whereas in hand more string is being used to go around a couple inches of gloved fingers.) Sorry for the windy comment, but this may help to explain why a perfectly tillered bow on the 'tree' isn't perfectly tillered in the hand.   
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