Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on November 13, 2017, 08:04:22 pm
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On an average length string say 60-64" how much do you think you can vary the length by twisting or untwisting?
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How much can you or how much should you?
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How much can you or how much should you?
How much should you? I figure when the twisting results in the string starting to bunch up it's too much.
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Just enough twists to hold the loops from slipping is ideal. Beyond that you start turning the string into a spring.
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I think minimal twists are best for longevity.my fastflite strings stretch about 1" after broken in.
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I'm wondering how close to the proper length you have to be when you make the string.
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Not sure if it’s just me being lazy but wouldn’t it just be easier to make 1 loop then tie a knot on the other end? In my little experience, keep the twist between 30 to 60 degrees.
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If you are making continuous loop strings it is simple to get them perfect length.
Make an extra long "trial" string, adjust it's length by threading it round and round through a loop of metal (an old bearing will do) this will give coarse adjustment, use twist to give fine adjustment to get the correct brace height. Use this trial string to set your jig for the correct length.
Use a good quality low stretch material (I use Astro flite, base on cost/performance)
The one in the pic is a bit of Ali' that I turned on the lathe, but any metal ring will do.
This also makes a very handy adjustable "long string" for tillering.
Del
PS. Don't shoot using that string, the metal ring will dent the belly of the bow (so a friend tells me ;) ::) )
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Good idea Del especially when trying to use a bowyers knot when making a heavy bow
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Good idea Del especially when trying to use a bowyers knot when making a heavy bow
I should christen it Del's ring of confidence .... remember that ad? ;D
Del
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Anyone know why is flemish string stretching? I made my first yesterday, from Spectra fishing braid and despite labeled as no creep and stretch, 70# breaking strength, it stretches when I tiller my current heavy bow.
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Very nifty Del.I like it.
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Anyone know why is flemish string stretching? I made my first yesterday, from Spectra fishing braid and despite labeled as no creep and stretch, 70# breaking strength, it stretches when I tiller my current heavy bow.
I'd guess the clue is in the name, it's fishing braid not a bow string material.
I try to use the same material all the time, that way I'll get consistent repeatable results when making strings to length.
Mind all strings stretch a bit, but with heavy bows you need decent material else it becomes almost impossible to brace them.
Del
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This spectra power pro fishing braid has been marketed as near zero stretch and creep. It shouldn't stretch at all.
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I use a timber hitch on the bottom,, and try not to twist the string that much,, sometimes I have to put super glue on the timber hitch to keep it from slipping,,
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You will get some initial "stretch" as the twists pull tight and the wax squeezes around. If you measure the diameter of a freshly twisted string and then measure it again after it's been tensioned you will see that the diameter has reduced. This reduced diameter becomes length.
You said over in your "Hazel Longbow" thread that the stretching had stopped. Has it started again?
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This spectra power pro fishing braid has been marketed as near zero stretch and creep. It shouldn't stretch at all.
If made correctly your power pro string should be as near zero stretch as the material can be. Let's see it and your loops.
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Yeah, maybe I wrote the post too late. Stretching stopped around the time I tillered to brace height, but still I find it interesting that it stretched for me before that. I suspect it had to do with twists.
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The number of twists seem to make it stretch more. When I started making strings they would seem to stretch, I thought the twists were slipping so I made the twisted portion longer, up to ten inches long. The problem got worse. People told me that 4" of tail was plenty. Finally I gave in and tried it. It worked. They "stretched" for about 15 minutes after the first brace and then they were solid. I use double loop Flemish twist. PITA to get the length right but I got tired of fighting with the timber hitch(bowyers knot), they do slip on FF IMO even with the double loop and extra wraps.
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DC,, if you put a knot behind the timber hitch,, it will stop, even on a small diameter string,,
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DC, what is the part of string you call tail? Immediately behind loop?
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Just enough twists to hold the loops from slipping is ideal. Beyond that you start turning the string into a spring.
Agree
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DC,, if you put a knot behind the timber hitch,, it will stop, even on a small diameter string,,
Do you have a picture? I'm having a hard time imagining it
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DC, what is the part of string you call tail? Immediately behind loop?
Yes, but to be more specific, when you are making the string and are just starting to form the loop, the ends that stick out I call the tails. Boy, this is tough and English is my first and only language ;D
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I will put a picture tomorrow of my string.
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Here is my string. This part behind the loop is probably too long and caused stretching.
(https://i.imgur.com/A133zLJ.jpg)
(https://i.imgur.com/esQ9NM5.jpg)
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No, you've just made it badly ;)
The section after your loop is cabling around the main body of the string, which is never good. Also, considering the weight you're trying to achieve with your current bow, the loop itself is way, way too thin.
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That fishing line is good stuff, but it is harder to work with than dacron-and I wouldn't say the string is too thin, but the stuff is slick right out of the box and needs lots of wax. I bet most of the stretch is coming from that loose loop.
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That's a messy unevenly tensioned string. Even no stretch stuff HAS to have stretch. When your strands are unevenly tensioned when laid up the string balances itself to the longest strand length. So all your errors are accumulating and manifesting as increased length.
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Sorry but I don't understand you guys. I could make a new one, but what does mean "cabling around", how is that uneven and too thin? Yes, its ridiculously slick, I rubbed a lot of pure beeswax onto it to make strands stick to each other and it still didn't get cohesion as I have with strings I bought for particular lengths.
P.S.
Forgot to mention, this is 20 strand string, with each having 80# breaking strength.
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Your blended part into the body of the string has one section going practically straight through and the other going around it like a snake. The straighter part is likely taking most of the load.
Just re-do this one.
Make a double loop too. Your timber hitch end isn't even twisted up at all really.
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Ah, I get it now. Why do you think that happened? I followed instructions where I twisted one bundle and counter twisted it with another and repeated the sequence over and over again. Bundles were held in place by one clamp so they shouldn't "move". Weird.
String is over 2 meters long and on other end it really has twists. Because of shorter bow timber hitch was basically on the place where I didn't put twists.
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Just a pic example here for ya FilipT.Might not be the best but you can see the difference???Counter twisting it tighter to stack them right next to each other as close as possible.Stagger out the plys too to give it a taperd look into the main string.
(https://i.imgur.com/xMrOdSu.jpg)
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Ah, I get it now. Why do you think that happened? I followed instructions where I twisted one bundle and counter twisted it with another and repeated the sequence over and over again. Bundles were held in place by one clamp so they shouldn't "move". Weird.
String is over 2 meters long and on other end it really has twists. Because of shorter bow timber hitch was basically on the place where I didn't put twists.
Uneven twisting of the bundles. A good idea is to really clamp your string tightly when first starting to twist and then put your loop sections around something solid so you can apply tension while blending the tails in.
If you pinch your two plies in a padded vise when first forming the section that will become the loop you can get a nicer twist started.. Then loop that around a peg etc to do the blend.
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I see the difference now, especially when I inspected my string couple of minutes ago. Well, it was a first try though haha. Btw, I like the color contrast on your string, mine is boringly green lol.
I'll make a new one today and post a picture.
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A very common newbe mistake, you twisted one bundle around the other instead of pulling them out to the side each and every time before you over lap the other bundle. After each wrap pull the bundle out and to the right.
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I made a double loop string. It looks a lot better, although it is a bit on the shorter side. Doesn't matter too much as I don't plan to make very long bows.
But for the future reference, when you make double loop flemish string without jig, how do you know how long will it come at the end?
Edit: who cares, I have board and nails and I am going to make a jig :laugh:
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You follow the standard formula when you hammer two nails in a board. That's a jig too. ;)