From: badger
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Date: 28-Feb-12 |
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I posted this in a thread a while back and had a good response on it and I often get questions on it so I thought I would dedicate a thread to it. I don't believe that absolute no set tillering is actually possible all the time but the ideal is to strive for it. No set tillering is simply a method of monitoring the condition of your wood as you progress through the tillering stages. Once you do this a few times you will find yourself cringing when you feel your wood start to give up a bit. Their are a few prerequisites to no set tillering. 1. You don't brace the bow when it is still too strong 2. Never! bend a bow any further than what it takes to expose an area that needs work. 3. Understand the concept of side tillering. 4. Be ready to accept that your bow may not be able to successfully reach the desired target weight and still perform as you wish. I like to use this with the mass principle so I know I have enough wood to start off with. Lets say your bow is floor tillered and ready to put on a tiller tree with a long string. The first step is to measure how much weight it draws at a specific amount of inches, lets say you pull the string 6", the tiller is perfect so you take a reading at 6" of 18#. Pull the same 6" about 20 times or so and measure the weight again. Is it still 18#? If not the wood is allready starting to breakdown. If it is still 18# then you are good to go. ( the 18# is just an example and will vary greatly depending on the length of your long string) If you did start to loose some weight some adjustments are in order as the bow will only continue to breakdown even further as you increase the draw. The first thing I do in this case is look for areas on the limb I can increase the bend, if the bend is nice and equal throughout the limb I simply need to make the stave a bit thinner and reduce strain keeping the tiller shape adjusted. Once I have made these adjustments I will need to remeasure my benchmark weight and start over. If you are new Jawges web sight will give you a good plan for when to brace the bow. Once the bow is braced the process starts over, draw the bow say 10" and note the draw weight, repeat that draw about 20 times and nothe the draw weight again, if it hasn't dropped and no adjustments are needed then go to 11" draw and repeat the process of several draws to 11". Now go back to 10" and see if the draw weight has remained the same. If it has not dropped advance to 12" and repeat the process, always going back to the 10" benchmark to see if the weight has dropped. Anytime you have to remove wood reset your benchmark to the furthest point you have draw it so far. Now simply continue with this procedure till you hit your target draw weight. One of the biggest losses of power in a wood bow compared to a glass bow is chalked up to hysterisis in the wood. By keeping the wood in a pristine condition you will be pleaseantly surprised at how little hysterisis wood actually has.
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From: John-Doc
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Date: 28-Feb-12 |
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Thanks Badger, I can tell this thread will help me optimize bow wood and have better success. Question, what scale do you favor for measuring draw weight during tillering?
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From: badger
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Date: 28-Feb-12 |
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John, I normaly use my brass Hansen scale but I also have a little Ultra Sport 50 electronic fish scale if I am being anal about it.
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From: woodshavins
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Date: 28-Feb-12 |
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I took note of what you had said in a previous thread, about getting the bow very close to final dimensions before bracing and really stressing it. I was very conscious of this with my latest bow. I subsequently have held onto 1" of the stave original 2.5" of reflex after 200 arrows. Performance is excellent.
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From: George Tsoukalas
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Date: 28-Feb-12 |
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Good one you, Steve. A good bowyer will use principles 1-4. Good to layout what you do regarding the rest. I will look at it closer. Jawge
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From: George Tsoukalas
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Date: 28-Feb-12 |
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Very nice. Sorry about typos as i am on iPod touch.
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From: bradsmith2010
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Date: 02-Mar-12 |
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thanks for the info,,,, i will try on my next one,,,
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From: dire wolf
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Date: 02-Mar-12 |
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Badger, I have posted on this topic many times. and no..I don't make whitewood or red oak board bows..:0
No one seems to listen or believe.
Repeat the same things that fail and you will get the same results..
It is magical..with a bit of attention and science thrown into the mix..and patient work.
The 'no set no string follow' self bow is NOT an illusion..Jim
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From: badger
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Date: 02-Mar-12 |
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Jim, thats the way I see it. I try to find ways to incorparate a bit of science into the backyard bow building process without getting overly tecnical. Steve
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