Primitive Archer
Main Discussion Area => Bows => Topic started by: mwosborn on April 01, 2013, 09:53:03 pm
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Working on a sinew backed hackberry. 60" ntn, 1-3/4" to midlimb tapered to just over 1/2" at tip. Tips are curved. Put in a small amount of reflex when I applied sinew.
I tillered the bow to 27" before applying the sinew. Tiller looked pretty good (no pics). Weight was at 42# or so. I then applied the sinew - 2 layers a week apart. Used hide glue. Let it dry for two weeks and then re-tillered yesterday. Gained a few # of weight with the sinew.
Again I got it to draw length of 27" and it looked pretty good. Let it sit over night and restrung it this afternoon. The brace looks terrible!!! It looked good yesterday!! I exercised the limbs gently to about 18" and the brace tiller began to look better. Continued exercising limbs out to the 27" and the brace was better yet (still not perfect).
Two questions -
1. Can someone explain to me what is happening?
2. What do you experienced guys recommend?
This is not my first bow, but I am still learning the ropes and any help would be appreciated. This is my second sinewed backed bow.
Here are some pics - Thanks!!
Pic #1 - side profile after resting.
Pic #2 - brace after resting.
Pic #3 - Drawn to 27"
Pic #4 - brace after being drawn several times.
Pic #5 - side profile immediately after unstringing.
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I'm not sure, but is it possible that one limb has more sinew than the other, or maybe has cured unevenly?
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Not for sure what the temp or humidity has been like where your at but rule of thumb on what I've read and heard is one month of cure time after last application on sinew. Just put on a sinew back Sunday so the end of April is next time Ill pick it up. May need to set for a couple more weeks?
Knapper
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Could be the sinew still drying
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I'd say it was still too much moisture left over from the sinew/hige glue. It could also be uneven sinewing or a combo of both. Let it rest in a cool dry area for a month and you will see a difference. Sinew/hide glue will cure out over a year or more and the draw weight and tiller can change over that time. Once it is fully cured out it will be more stable but will still get a bit mushy during humid weather.
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That bow is beautiful either way love the side profile of it
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Looks like it's more stressed on the lower limb. Not that uncommon if you use the step through method or push/pull to string. Goes away after a bit, or if you then stress the upper limb.
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I'd say it was still too much moisture left over from the sinew/hige glue. It could also be uneven sinewing or a combo of both. Let it rest in a cool dry area for a month and you will see a difference. Sinew/hide glue will cure out over a year or more and the draw weight and tiller can change over that time. Once it is fully cured out it will be more stable but will still get a bit mushy during humid weather.
Im quite sure thats the problem, as Ive done it myself!
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Thanks for the input guys! I will put that one on the back shelf and let the hide glue and sinew cure some more. Will have to start a new one in the mean time! ;D