Primitive Archer
Main Discussion Area => Bows => Topic started by: eflanders on April 23, 2011, 02:07:09 am
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Is there a "best way" or some sort of good trick to determine the proper strng groove angle? I had used 45' on a few and I now think that a set angle may not really be appropriate based on varying bow lengths, tip reflex, etc.
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The way I was taught is to just groove the back of the bow until you get it to the short string (at brace height), then just mark where the string lies and that's where your groove goes.
Another trick to get both sides even is to have two files, and after one side is done, flip it over in the vice, put a file in the groove (now on the bottom) and use that to line up the other side evenly.
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I finally started to get them good after looking through Gordon's hazelnut build-a-long in the archives, and when I get the bow ready to finnish I heat up a 16 penny nail with the torchand burn them in, gives it a real nice look and slick's them up good, Bub
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I think the best way is to start with say 45 degrees and then just look at how the string sits in the groove at brace and full draw. If it is bending through a sharp angle then radius the groove a bit at that point until sits nicely.
I don't think there's any magic formula, just adust 'em so they fit.
to me it's part of the final finishing and tweaking, it is also an oportunity to make sure the string is sitting right and the bow is pulling back true, a bit of fettling can help counteract twist and get the string on the centreline (or wherever you hapen to want it)
Del
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I really don't have any set way of doing this. I just do it by looking at it. File them in lightly string look file look fille. I guess I just do it a little at a time. I think once you get the look in your head you just know the angle. At least I do. I've never really thought of this.
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I start with temoprary grooves on the sides of each tip cut at about 45deg angle and cut deep enough to hold the tiller string until the end when I cut the finished grooves. Never cut across an unprotected back! I start these temproary grooves about 3/4" to 1" down from the tips.
Once I get to finishing up the tips(near the very end of the building process) I will brace the bow and trace the string with a pencil on the belly, the sides and across the back if I have an overlay. I then cut the final grooces to those pencil marks.
Everything outside of the string groove(at the very tips) is dead weight and most of it is not necessary so I shape this to eliminate excess physical weight and to make the tips attractive.
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I just kinda eyeball it and adjust a bit like Del as needed.
Darcy :)
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I use an adjustable bow stringer with leather straps on each end. Once the bow is at desired draw length and close to desired weight.
I will then place it back on the tiller tree, draw it to desired length. At this point I place a string line on the knock point on the bow string
and then pull the string tight to the desired knock point on the upper limb and then make the mark.
For the lower limb, I do the same, but I have found by doing this.... The lower limb knock angle will be ''slightly'' more than the upper due to the fact that I shoot with one finger above, and two fingers below the arrow knock. After I have made the marks, I remove the bow and cut the grooves, then I will make a new string for the bow.
Maybe I am over thinking it, but this is how I have got better result, regardless of the bow over all length.
one can not find the exact string angle unless you know the draw length and the radius arc of the limb.
With that said the exact string angle can be found for a specific bow once the limbs are near perfect tiller.
Any replies are welcomed.
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There are buildalongs on my site. Jawge
http://georgeandjoni.home.comcast.net/~georgeandjoni/
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Thanks for all of the suggestions folks! Tracing the string angle at full draw just makes so much sense I'm embarrassed to not have thought of this myself :-[
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Thanks for all of the suggestions folks! Tracing the string angle at full draw just makes so much sense I'm embarrassed to not have thought of this myself :-[
I don't think full draw is so much of a prob, as the string will likely be somewhere near 90degree and won't be making much contact with the noch except at the back of the bow (unless you have some extreme recurve). I thin it's at brace where it's possible to end up with the string bending through quite a sharp angle onto the nock. This is the potential wear point, and that irritating point where the serving parts like the Red sea to reval the string beneath. It's that sharp bend that needs smooooothing out IMO.
Del