Author Topic: Yew bow crack around a knot  (Read 7085 times)

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Offline WillS

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Yew bow crack around a knot
« on: March 22, 2016, 02:48:14 pm »
Any ideas?  ;D

This one is a whopper of a knot, and it's ticking like a time bomb at exactly 27.5" drawlength, and opening up the crack you can see running vertically downwards.  I'd like to get at least 29" out of it for safety, so open to any and all suggestions for ways to solve this.  If it's solvable.

I'm also open to being told it's going to make a lovely walking stick...


Offline PEARL DRUMS

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Re: Yew bow crack around a knot
« Reply #1 on: March 22, 2016, 02:50:26 pm »
I'd just keep building and hope it stays within the bow.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline WillS

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Re: Yew bow crack around a knot
« Reply #2 on: March 22, 2016, 02:54:38 pm »
The bow's done, it just keeps cracking at 28".

Offline PEARL DRUMS

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Re: Yew bow crack around a knot
« Reply #3 on: March 22, 2016, 02:59:15 pm »
But does the crack leave the bow? Osage doesn't mid cracks providing they stay within the bow and not run off an edge
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline Pat B

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Re: Yew bow crack around a knot
« Reply #4 on: March 22, 2016, 03:43:03 pm »
I'd draw the bow too pen the crack, inject some thin super glue and let the bow down to close the crack. At least give it a shot...unless you really need a walking stick.  ;)
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline WillS

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Re: Yew bow crack around a knot
« Reply #5 on: March 22, 2016, 04:05:16 pm »
The crack is staying well inside the profile.  Maybe it'll just run along the limb if it opens further...

Offline PEARL DRUMS

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Re: Yew bow crack around a knot
« Reply #6 on: March 22, 2016, 04:06:11 pm »
I think it will stop running, just a hunch.
Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.

Offline Del the cat

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Re: Yew bow crack around a knot
« Reply #7 on: March 22, 2016, 04:11:46 pm »
Only sure way.
Rasp it out into a long shallow scoop and lay in a patch of sapwood.
I've just done a similar thing on an all heartwood Yew Primitive.
Knot shown here:-
http://bowyersdiary.blogspot.co.uk/2016/03/heartwood-yew-improving-tiller.html
Patch shown here:-
http://bowyersdiary.blogspot.co.uk/2016/03/knot-what-knot.html
If you want to keep the character you'll just have to risk leaving it, which will be Ok if the bow isn't too heavily strained. The bows I have with big knots like that I tend to keep as "show bows".
If I actually want a fix, the long shallow back patch works every time.
Make it about 4inches long and about half the depth of the sapwood so that some of the original sapwood remains continuous.
Del
« Last Edit: March 22, 2016, 04:15:59 pm by Del the cat »
Health warning, these posts may contain traces of nut.

Offline wizardgoat

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Re: Yew bow crack around a knot
« Reply #8 on: March 22, 2016, 07:02:38 pm »
Does the crack touch the lip of the knot hole?
I'm not one for sinew or rawhide patches, just not my thing, but it could work on this bow.
If it were me I'd do as suggested and fill the crack with thin super glue. Heat the wood up a bit, bend the bow to open up the crack a bit and fill it up.

Offline WillS

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Re: Yew bow crack around a knot
« Reply #9 on: March 22, 2016, 08:07:22 pm »
Yeah it sort of trickles over the lip.

I don't like patches either.  I don't like the look of bows that have them so I tend to find other ways to solve problems. 

One of the problems here is that I can't open the crack at all!  It's tiny - too small to get a fingernail in for example - even when braced and drawn partially.  When I first spotted it (after hearing the tick at full draw) I flooded it with thin superglue and it just ticked again at full draw and the crack got slightly longer. 

I'm wondering if it will just keep running along the bow further each time it's drawn to 28", or whether it will stop at a certain point and be stable until drawn further.

Offline wizardgoat

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Re: Yew bow crack around a knot
« Reply #10 on: March 22, 2016, 09:16:56 pm »
Hmmmmm I don't like that it's over the lip.
All the tension forces are concentrated on that lip.
I've made a few bows that had knots/branches with the puckered lip sapwood around it.
I like to knock them down, id rather violate them and have them smooth.
Every yew bow I've seen fail (except one) have been tension fails around knots or concave sections in the sapwood.
I'd consider knocking the area down, sanding it smooth, sinew wrap the area once or twice, and leave the area a little stiff. Or just go for it, but you will flinch every time you draw it

Offline Del the cat

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Re: Yew bow crack around a knot
« Reply #11 on: March 23, 2016, 03:14:01 am »
...I don't like patches either.  I don't like the look of bows that have them...
If you do them right, they are virtually invisible.
Maybe do a try out on an old broken bow limb, you may be pleasantly surprised, it will look less bad than a load of sinew or thread.
It gives a good glue area, keeps the flow of grain and the line of the join all in line with the stress.
Del
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mikekeswick

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Re: Yew bow crack around a knot
« Reply #12 on: March 23, 2016, 03:24:02 am »
Sinew wrap. If you prepare your sinew fine enough you will hardly be able to see it. Burnish the sinew once dry.
Glue isn't going to do anything to help the bow.

Offline WillS

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Re: Yew bow crack around a knot
« Reply #13 on: March 23, 2016, 04:10:19 am »
Sinew wrap. If you prepare your sinew fine enough you will hardly be able to see it. Burnish the sinew once dry.
Glue isn't going to do anything to help the bow.

Yeah that's my worry.

A wrap makes perfect sense, but annoyingly the crack is in a hollow just below that knot.  I can't get any contact with a binding there at all.  It's also not really opening up at all, so I don't know how much good sideways pressure from a wrap will help?  Hopefully I'm wrong!

Offline Pappy

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Re: Yew bow crack around a knot
« Reply #14 on: March 23, 2016, 04:26:35 am »
My hunch is she will blow, I would put it on the tiller tree[where I could get back a bit] ??? and pull it to 29 and see what happens, ticks are usually fatal in my experience. ;)
 Pappy
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