Primitive Archer
Main Discussion Area => Bows => Topic started by: sieddy on March 10, 2015, 04:39:08 pm
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Hi fellas as the title says the Hazel stave bow that at the weekend was pulling 44#@26" and had an inch and a half of string follow. Is now showing 36#@26" on my scale and has a ton of set! :o
I can see how the backing could be inhibiting the bow from returning to straight but how could it reduce the drawweight?
I'm a bit gutted as it was my most successful bow to date- ah well another lesson learned!
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Heat treat it, hazel responds well to heat treatment.
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Do have any pics of it? Braces or drawn?
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Hey Vmb I already toasted the back before I'd backed it! But I will take the backing off and heat treat it some more. Thanks.
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When you glued it up if you induced a little reflex it might not have gained all that set
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Hey Wiz- no I've only got a couple of pics from before I backed it.
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You heat treated the back? Under the backing?
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The backing fibres were quite wet (I dipped them in water then wood glue squeezed the excess out then layes them on) Do you think the damp could be the culprit?
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Hi Pearl drums- no I heated it before I put the backing on.
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Why did you heat treat a bows back?
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No sorry I mustn't have been clear. I heated the belly.
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I see now I was clear and also wrong. I definitely didn't heat the back! :o
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The backing fibres were quite wet (I dipped them in water then wood glue squeezed the excess out then layes them on) Do you think the damp could be the culprit?
Yup the moisture wicked into the bow basicly making it warp, if you would have added some reflex it should have been fine after it dried out
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Ok, I was about to ask just what part of that you missed the last year!
If the bow is challenged, i.e. too short, too narrow, poor tiller and so on. It probably just caught up to you after a bunch of shooting. I see quite a few bows posted that claim 1/2" set, 3/4" set and so on. Maybe that's true hot off the press, but lets talk after 500-1000 shots. Most of us build too many bows to even hit that number with a good share of them.
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Damn this game is hard! :o
Thanks as always for the input fellas. :)
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I'm not understanding... Either the scale was wrong, or you were shooting the bow while the backing was still wet?
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Hi Jojo that's what I didn't get I left the bow while the backing was drying and the scales are fine (they are not the best but are consistent)
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Was the bow shooting at full draw and then you decided to back it?
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Hi Pat. Yeah I was a little concerned about the back after scraping off the cambium. I thought the backing couldn't hurt! ::)
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if the backing put moisture in the bow, it would need to dry a week or two before shooting again,if it is humid where you are,, maybe even needed a heat box,,, sounds like a moisture content issue,, maybe hemp attracts moisture more than other backings,, I have not tried it,, try putting the bow somewhere very dry, and see if the weight goes up,, I am not sure if the set can be fixed,,
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Hi Brad thanks for chipping in - i definitely think it was the moisture. I'll have to live with the set but will get the backing off and see what I can do to save it.
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Whenever I use Titebond to glue on cherry bark backing, it raises the bow's moisture content quite a bit. Like Brad said, either let it dry for a week or so if the RH is low enough or put it in a hot box before shooting it. I haven't had any set issues after getting the MC back down before shooting it in.
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It might not be anything to do with the backing at all.
A white wood bow needs to be tillered perfectly, kept incredibly dry while being worked and then lightly toasted and sealed with a good modern sealant. If not, it will take set regardless. Taking set will reduce draw weight.
It's not unusual to finish tillering a bow that has zero set, and after a few weeks of shooting end up with a banana. Tillering only goes a very small way to work the bow, whereas shooting is much tougher on it. You can get close to emulating the stress when tillering by exercising the limbs a LOT as you increase the draw length - say 40 times every inch - but it will still take some set as its shot in.
Any white wood bow needs to be tillered delicately as well - some woods let you pull the bow until you see an obvious hinge and then resolve the issue, but most white woods (ash and hazel in particular) don't. You need to be spotting hinges before you even see them, predicting where its moving too much, and visualising where it's going to hinge as the draw length increases.
They're great woods for bows, but fickle and fussy!
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I wouldn't remove the backing at this point. First try to post some pictured of the bow, also at partial draw. We might find another culprit for the set.
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Thanks for the input fellas I will post some pics tomorrow for the postmortem but sadly I have already taken the backing off.
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I'm the type person that constantly moves forward. On my own turms.
MOVE ON LEARN FROM THE EXSPERANCE.
BUILD ANOTHER BOW.
If you stave was seasoned enough. That was'nt your problem.
It's low weight so that did cause your problems.
So I hate to say it but likely was your tillering.
I never fix a bow if it was my faught. And even then very liky it's worth fixing anyway. Your just trying to save a little face. You never want to make that misstake again. So don't try to fix it. MOVE ON build another bow, not makeing that misstake again.
Each time you make a bow the more insight you have into building another.
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Hey Crooketarrow I hear you man and I myself am quick to move on from my mistakes -I have a few works in progress to get on with! :)
But I will have a play around with this bow to see what results prior to putting it in the fire. I ain't got nothing to loose now have I. :D
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I find it hard to believe dryness was an issue. Reason being, it would have never registered numbers that high to begin with. Wet backing give up the ghost right away. Been there.
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I think it registered high unbacked and then he added the backing and started using it while the bow was still damp.
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Ahhhhh. That makes sense.
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Yes, that does make sense.
Here is another possibility.
Sleddy, while tillering out the stave did you exercise it 10-20 times after each wood removal?
I am thinking that you may not have and it finally caught up to the stave.
Jawge
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Hi Jawge yes I do exercise the limbs throughly throughout tillering.
PD & Pat l- I agree entirely that I should have left it a little longer. But I only started playing with the bow last night and the backing was bone dry this morning when I pulled it off!?!
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So, did you register that heavier weight AFTER you backed it, or before?
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I'm not being defensive I appreciate that this is my mistake i am just interested to learn from it. I have maximum respect for the support that is available on this great forum! :)
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I was getting the heavier weight before I put the backing on
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500-1000 shots. Most of us build too many bows to even hit that number with a good share of them.
yeah, only my favourites and giveaways make it past 1000 arrows.
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I think you'll find that the hemp is too stiff for the not too great in compression hazel's belly.
The stiffness of the backing has caused more of the bows 'load' to be shifted to the belly causing the extra set.
100% that's the reason. Remember to make the resistance to tension/compression the same in any and every bow you make.
Trapping is done for the same reason eg. to help out tension strong compression weak woods, heat treating is the same but unfortunately you've increased the strength of the back gving the belly no chance. The lost weight and set tell the story.
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Hi Mike thanks for that it's really interesting. I didn't think hemp would be too strong but when dry it was like fibre glass (very tough!). Anyway as I was putting it on I was thinking "there ain't no call to be backing Hazel!"
Looking on the bright side only put it on as an experiment prior to using it to back an Elm and a Yew bow. I've learnt some valuable lessons before getting into those more valuable peices of wood!
The Hazel bow is now pulling 40#@26" and has about 2.5" of set. So I can have some fun shooting targets in the backyard with it anyway :)