What is the difference in long and short string tillering?

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What is the difference in long and short string tillering?

Quest for fire
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Quest for fire
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Joined: March 22nd, 2007, 6:19 am

June 28th, 2007, 5:33 pm #1

Can you use one or the other? Is there a definite system as to when you use one or the other.
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toxophileken
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June 28th, 2007, 6:32 pm #2

George has developed a system he relies on and that works consistently for him, with a long string. It is described on his website.

I haven't had much luck with it... I think because my bows vary in length and geometry (or I am doing it wrong). I think if you use consistent methods, you can anticipate what the bow will look like braced from looking at it on the long string. I, personally, am not there yet.

Tim Baker told me to "get it bending even while floor tillering, and get it braced right away after that." Hope I'm quoting him accurately. I may have been taking him too literally, as I have been stringing my bows 30#-40# too heavy, and noticing a certain amount of set...

The limbs pull on each other when braced... You don't get the same shape on long string. On long string, the outer limbs look stiffer than they actually are.

Since I have gotten better at floor tillering (I still use a mirror to help me see), my bows have usually been very close to even at first brace. Browse through my Slowmotion buildalong to see a few first brace photos. Once the bow is braced, any unevenness can be quickly seen and corrected, often without unbracing.

But I still don't know what I am doing yet, so hopefully some of the gurus will chime in here.

Ken
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DCM
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June 28th, 2007, 6:53 pm #3

I use the shortest long string I can, if that makes sense, until I get the bow up to 16" to 20" on the tiller tree. Then I brace the bow about 3" to 4", take it down almost immediately (my purpose is to check for string alignment generally) and look for any signs of set, make necessary corrections and proceed from there. It is very important to get the tiller looking good before you brace the bow, and little incentive to brace the bow too early for the reasons Ken cited. As I approach full draw, say 3" short of full draw, I brace the bow to full brace height, 6" for me. A long tillering string will tend to show stiffer outer limbs than a short string. It's all about the string geometry, if that helps.
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Quest for fire
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June 28th, 2007, 8:14 pm #4

Since I have gotten better at floor tillering (I still use a mirror to help me see), my bows have usually been very close to even at first brace. Browse through my Slowmotion buildalong to see a few first brace photos. Once the bow is braced, any unevenness can be quickly seen and corrected, often without unbracing. Quote

It sounds like you are saying I could shave the wood while it is still braced? If not what are you saying?
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I get the idea from you why the long string shows the outer limbs to be stiffer than they actually are. I just do not see the advantage of the long string. Is it due to the fact that the long string does not overstrain the bow when not being pulled on?
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tom sawyer
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June 28th, 2007, 9:08 pm #5

I use a long string (shortest possible) until the bow is beinding to equivalent of a good 6" brace height. Then I string and only long enough to find places that need work. First few times strung, I don't usually even pull on it.

The difference in long and short string, is both string angle and the short string puts an additional stress on the bow. The long string makes the bow appear to be heavier than it is, because the string angle gets large faster. I don't bother to use a scale with a long string, it serves no purpose for me. I can tell by how hard it is to get on the tiller stick, sort of where the poundage is. I can also tell by how hard it is to string, if I'm struggling then it is over 70lb and I need to reduce before trying to string at all.
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Mark in England
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Mark in England
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June 28th, 2007, 9:27 pm #6

Using a long tillering string can be misleading. I have found it is easy to end up whip tillered if I use a long tillering string too much ending up with a bow that needs shortening or more wood taken out at the handle and mid limb and thus a weaker bow.
Along string to get to brace height and then a final length string from there seems to work better for me. Obviously it helps if you make sure you are not over weight on the long string before making that switch.
Mark in England
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toxophileken
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June 29th, 2007, 12:04 am #7

QFF, yes, I frequently scrape on a braced bow. I even have been known to use a rasp, less frequently.

I have also been known to cut a tillering string nearly through with my scraper... Didn't blow on me, thank goodness.

This method is especially useful on kids' bows and bows that are very flat and thin in cross section, as a tiny amount of wood removal shows up quickly.

Ken
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George Tsoukalas
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June 29th, 2007, 12:10 am #8

Quest, see Bow Making Directions on my site and the buildalongs where I go through my system of using the long string. Length of it doesn't matter. Jawge
mysite.verizon.net/george...rcher.html
http://mysite.verizon.net/georgeandjoni
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Woodbear
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June 30th, 2007, 2:03 am #9

I use the long string for tillering to get to brace height with the bow still a little over weight. That is I expect to be able to bend the bow so the tips deflect enough for about a 4 brace height with the long string. The long string should be equal to the length of the bow, and the weight needed to get this 4 deflection is about of the intended draw weight.

For a finished bow, if you put a long (equal to the bow length) string on it, it should take about 40% of the bows draw weight to deflect the tips to a brace height of about 6inch. This is similar to what you do when you string a bow with a bow stringer. When a bow in progress is on the tiller tree or stick, deflecting the tips by 2/3 of the intended brace height with 50% of the intended draw weight should provide plenty of margin for not coming in light, while not over straining the bow, and enabling you to get a normal length string on it for further tillering. You can then slowly raise the brace height to your real value as you near the final draw length in the tillering process.

For those mathematically inclined, I have included a diagram I made of the stress distribution in a bow with various methods of bending the bow to brace height. These methods correspond to; being bent by the push-pull method (yellow line), being bent by a bow stringer (green line), and when held at brace height by the taught bow string (red line). The upper green line is the stress at full draw for reference. Note that the stringer stress distribution (shape of the curve) is most like the full draw stress distribution, but at a reduced value everywhere. When normally braced, the bow is relatively more stressed out near the tips than near the handle. This is why the brace height bend looks different with a long string compared to when normally braced.



Dave
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Quest for fire
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July 2nd, 2007, 4:43 pm #10

Thanks Woodbear. I finally found a floppy to copy that information on. I will have to have a double large cup of coffee to copy that in to the organic memory bank.
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Hin Kraka
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July 2nd, 2007, 5:23 pm #11

Great info and intel peeps! How much do you go long-string if you even go? And what is the difference between longstring- and floor tillering? Except from how you do it of course! =)

QFF: Do you people still have floppys?//Jakob - Welcoming the spring, new love and any opportunity to work with his hands!
//Jakob - too little time for all interest and hobbies!
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Woodbear
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July 2nd, 2007, 7:56 pm #12

I think of floor tiller, and long string tiller as accomplishing the same purpose, namely to get the bow bending enough to put a real string on without being over stressed. When floor tillering one end of the bow is on the floor, and the handle is pushed to bend the bow a little while observing the way it bends by eye. With experience you get a feel for how much pressure should produce how much bend. The rub here is developing the experience.

Long string tillering with a few extra precautions, like having the string length equal to the bow length, and pulling with a scale, can get the bow to brace height in a more controlled manner. If you pull with the draw weight, and get less than 1 deflection, there is no question, more wood needs to come off. However, even at 1 deflection you can still get some idea if there are large errors in the evenness of the bend.

To me, long string tillers job is done once the bow can be strung at a low brace height.

..Floppy disk?........ It is hard to find a computer that will accept one these days.

Dave
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Ransom
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January 15th, 2008, 10:51 pm #13

what is short tillerin
Find out more: http://www.jamesransom.net


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Rod
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Rod
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October 15th, 2015, 9:53 am #14

I don't use a long string after I can brace the bow. 

Rod.
Last edited by Rod on May 10th, 2017, 9:22 pm, edited 1 time in total.
It's meant to be simple, not easy.
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