Primitive Archer
Main Discussion Area => Bows => Topic started by: Shiloh on February 05, 2013, 11:12:41 pm
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Hey all, I've got a little problem that's come up with my most recent build. It's a figured maple board bow, measuring 72" TTT, 2" wide at the fades and tapering to 1/2" tips. I'm shooting for 48 to 50# @ 28". The handle is six inches long, and 1" thick (I'm not gluing a riser on, just going to layer some thick leather or fiber to build it up a bit).
The issue I'm having is this: I've got it roughly tillered at low brace, about 1" above the handle, and it looked good enough for me to try for full brace. But when I first tried it, with the string a little more than 3" from the nocks, the string was only about 3 1/8" above the handle. Now I know that in general longbow strings sit about 3" below the nocks at full brace, so I'm a little worried as to why mine isn't. I'm using a relatively new B50 string, but it's stretched pretty much to its full extent. Any ideas what I could be doing wrong?
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Shorten the string. But that much twisting will reduce preformance
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Shorten the string, don't worry about where the string lays when the bow is not braced up.
Newindian, how does twisting the string up reduce performance, and how much does it reduce performance as compared to a string not twisted much?
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A shorter string weighs less, I didn't mean to say that the twisting is a what causes the performance drop. This was brought up in a resent topic I doubt that the effect would be very, if at all, noticeable.
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Twisting the string will cause it to keep stretching and acts like a coil spring it will reduce performance a lot ,fewer twist stretches less and will perform much better. :) :)
Pappy
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Roy has nailed it.
The unbraced measurement is just a sort of get of jail, rough guide measurement for people with ELBs who don't know how long a string to order when they are buying one!
I know some of you guys (like me) won't understand the concept of 'buying a string'... I think it's a sort of arcane ritual practiced by some newbies to archery. ;D
That's why I use my magic toggle* to adjust string length while tillering, I then make up the final string to suit.
Del
* bit of 3/16 x 1" aluminium rectangular bar (or really hard plywood) with a couple of BIG holes drilled through and smoothed and rounded off.
A long string can be threaded through the holes round and round to shorted it. Bit like a figure 8 the string getting wound round the middle 'bar'
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Thanks guys, it just had me a bit worried.
Del: Now THAT is an awesome idea! I'll have to give it a shot.
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Pics Del? I apologize - I'm much more of a visual person. :)
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Shilow, is the bow tillered out or are you still tillering. If it is too stiff to brace safely leave it braced at 3" until you get the weight down enough to get a higher brace.
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Shilow, is the bow tillered out or are you still tillering. If it is too stiff to brace safely leave it braced at 3" until you get the weight down enough to get a higher brace.
I'm still tillering, but I don't feel that it's too stiff to brace fully.
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Pics Del? I apologize - I'm much more of a visual person. :)
Oh I see... I'm just your picture monkey ;)
Del
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Okay, am I just being picky about this or something? I got it to something resembling full brace, just a hair under 5 1/2" from the handle. But the string is almost 4 1/2" from the tip. Am I doing something wrong?
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Yes, you are trying to explain without pics. We need pics!!!
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Where are you measuring the string 4.5" from the tip? I'm lost. Like Pat said.....PICS
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Hehe, you're probably right. ;D Forgive the horribly messy garage:
(http://i.imgur.com/CA5bdZQ.jpg)
Braced profile. The string is braced 5 1/2" above the handle in this pic, but when it's unbraced the flemish loop is 4 1/2" from the string nock.
Also, if you're interested here's a pic of the tiller about halfway through. Any thoughts?
(http://i.imgur.com/1XTRiQr.jpg)
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Defiantly not an expert, but it looks like your bending to much on the left in the outer mid limb and have a fair amount of propeller twist
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The central 1/3 of the bow is doingvery little... ok there's a grip there, but do you really want it that long?
Try my trick of holding a CD up in front of it, you may want to move it across to look at each limb separately if you do want a longish stiff grip.
It looks to me like you are in slight danger of ending up with it whip tillered or what I call square tillered with the central 1/3 not moving the a hinge in each limb and the tips pulling straight back (I'm exagerating to help explain).
Del
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Thanks for the tips, everyone. Del: Good point about the middle portion of the bow. Unfortunately, I over-estimated how big I wanted the grip when I laid it out, so it's stuck that way. :(
And as far as the propeller twist goes, should I just scrape some wood off the opposite side of the twist to even it out some?
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Don't worry about how long the string is. If you hit the brace height you want the string length doesn't matter.
Looks like your bow is stiff towards the handle area. Bring the bend back towards the handle more.
About the twist, feet the thickness of the limbs comparing both sides of each limb. The side that is thicker should be reduced.