Primitive Archer
Main Discussion Area => Bows => Topic started by: upstatenybowyer on February 19, 2017, 08:18:12 pm
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As many of you know, I'm still quite green when it comes to making strings. I'd really appreciate your thoughts on how you would determine the right string length for a 5" high brace on the following bow...
Osage bendy handle
65# @ 27"
58" ntn
I was thinking 3-4" less than ntn length making it 54-55" long?
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When I get a bow to full brace with my tillering string I measure the distance from loop to loop and make a new string that length.
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When I get a bow to full brace with my tillering string I measure the distance from loop to loop and make a new string that length.
Makes sense. Thanks
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I've found that 3" less than NTN is about right for a longbow. I also found that making a string that turns out to be that length can be tough. You may find yourself re-doing that second loop a time or two. Guess how i know that? ;D ;D
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I figured out an equation for determining string length. However, it is very complicated and would be too much of a hassle to explain. For a 58 NTN at a five-inch brace I calculated a string length of 56.5 inches. However, that's for a non-stretching string, which most will at least stretch a little. I would go with 55.5 inches assuming 1 inch of stretch and see where that puts you.
I find that 3-4 inches shorter than the NTN length is a good rule of thumb depending on the stretch of the material, unless it's a recurve, then it needs to be about 1-2 inches shorter than where the recurve meets the working limb.
*correction was made. I forgot brace height is usually measured from the belly not back so i had to re-calculate for handle width (which i assumed to be 1.5 inches). That changed the result from 57.1 inches to 56.5.
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Hi, I would err a bit on the longer side without having the string twisted much. I then would correct it by twisting the string until I hit the right brace height. To me this is better than having it too short.
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3 shorter for long bows and 4 shorter for recurves is what I use, unless I do like Clint which is the way Jon makes them, just measure from nock to nock when I have it braced with the tiller string, either way will work pretty good for me , but I usually brace most of mine 5 1/2 to 6 and use lower stretch D97.
Pappy
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If your going to do the endless loop i would measure the exact length with a tillering string or something like osage outlaw said. I personly use a timber hitch so its much easier to adjust if the length is wrong.
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I have a long string for tillering that I thread through a loop of alluminium to adjust it's length (an old bearing works too).
This allows you to slowly bring up the brace heigh when tillering (twisting gives fine adjustment). When I'n ready to make the real string I put the tillering string on my jig to get the right length. It works 100%
Del
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Strings can be a pain in the beginning learning to make them but after a while it is'nt bad.Double loop that is.
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neat set up dell! I make strings in an odd way being that I make the hem into a rope and back splice .I think it's very important to have minimum twists or it will fray and have a shorter life.with fastflite it will stretch about it one" after the splices tighten up.
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When you shorten the string what do you feel is the maximum twists per inch?
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Thanks for all the replies guys. I was able to make one at the perfect length. Turned out to be 3.5" less than ntn. I made a string jig and followed the video with cute girl who's speaking in a different language (English dubbed). Someone here recommended it. ;)
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Personally I'd rather use a string that's only twisted 10 to 15 times opposed to using a string that's twisted 40 times.
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That's kind of my way of thinking. I was watching the video that Upstate mentioned the other day and she said twisting 20 -60 was OK but 40-50 was best. It seems to be a good video so it got me wondering.
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The more twist the more like a coiled spring....I like as many twists as I use strands of string. I've never 'tested' it but extra weight of string (too long) and extra twists has got to lose you speed.
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Yes less twist is better like mike said. I use 3 twist per inch as a rule. :)
Pappy