Author Topic: Yew belly grain  (Read 1089 times)

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Offline DC

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Yew belly grain
« on: November 24, 2019, 06:45:18 pm »
I'm working on a Boo backed Yew that wants to hinge right where this irregularity is in the belly. The belly is flat and the thickness taper is good in this area. I'm treating it like a thin spot and scraping all around to relieve the strain on it but I can't seem to get the hinge to go away. There is no sign of chrysals there, yet. Do you think the wood may be slowly collapsing in this spot? Ever had this happen? More pictures on request :) I'm at full brace and 40@ 24" so I'm running out of wood.
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Offline aznboi3644

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Re: Yew belly grain
« Reply #1 on: November 24, 2019, 06:54:08 pm »
Looks like the grain running around a pin knot.  Maybe the fibers arenít in line with the rest and isnít as strong causing the weak point.

Offline DC

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Re: Yew belly grain
« Reply #2 on: November 24, 2019, 07:04:01 pm »
You made me go look at it again and there is no indication of a knot. But what I did notice, and you can see it in the picture, at the top the wood is a little lighter colour. That's because it's sapwood. The sapwood dipped in the billet there so when I sawed it out there was still a bit of sapwood there. I didn't think it mattered because at the time there was lots of heartwood. As I tillered I reduced the heartwood until what I've got now is about 50% sapwood in that spot. Maybe it's collapsing.
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Offline Weylin

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Re: Yew belly grain
« Reply #3 on: November 24, 2019, 08:48:51 pm »
That's interesting. Sorry that it's giving you trouble. It goes to show the difference between yew sapwood and heartwood. I hope you can make it work.
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Offline DC

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Re: Yew belly grain
« Reply #4 on: November 24, 2019, 09:27:02 pm »
Yeah, I cut a bunch of billets from small diameter Yew trees so in spots the sapwood still shows. I've used it like that before with no problem but I guess it depends how much there is. I'll have to watch that from now on. That's what I get for trying to try to stretch my Yew stash.
Of course I'm still speculating that the sapwood is my problem and that it's not the grain wiggle.
Vancouver Island
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Offline PatM

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Re: Yew belly grain
« Reply #5 on: November 24, 2019, 11:26:38 pm »
If those growth rings were laminations what would you expect to happen?

Offline DC

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Re: Yew belly grain
« Reply #6 on: November 24, 2019, 11:53:19 pm »
I'd expect them to crush together. That's what I was thinking until I thought of the sapwood thing. My minds still open though. I'm kind of waiting for someone to say,"That happened to me too."
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Offline bownarra

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Re: Yew belly grain
« Reply #7 on: November 25, 2019, 01:27:10 am »
Straight grain can resist compression because it is flat :)
When you have a dip like that the fibers are no where near parallel with the surface of the limb thus causing a weakness in compression.
I learnt on (on the edge~) ipe bellied elbs that straight grained belly wood is somewhere as near important as a straight grained backing is.
Yew sapwood isn't great in compression BUT I've had it on a small spot on belly lams with no real issues. The problem is the grain or at least most of it.

Offline Del the cat

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Re: Yew belly grain
« Reply #8 on: November 25, 2019, 02:38:35 am »
Never had a problem like that. I've had plenty of undulating grain and hints of sapwood in the belly.
Could just be soft spot in the wood, I don't think there is problem with grain direction, Yew isn't fussy.
Rasp out a shallow scoop and patch it.
My 50# boo/yew flight bow that won a comp' had a belly patch !  ;D
Del
Health warning, these posts may contain traces of nut.

Offline bradsmith2010

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Re: Yew belly grain
« Reply #9 on: November 25, 2019, 09:11:57 am »
Try leaving it thicker like u been doing,..if u come in under weight...the bow could still be a shooter...

Offline NonBacked

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Re: Yew belly grain
« Reply #10 on: November 25, 2019, 09:40:54 am »
DC Ė Could you take a picture of the hinged limb at brace or maybe at 20Ē? If the hinge is significant at this point, it may have damaged the wood beyond repair.
H

Offline PatM

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Re: Yew belly grain
« Reply #11 on: November 25, 2019, 10:15:11 am »
I would just reduce the whole belly and apply an entire new belly and leave  what you have as a core.

Offline DC

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Re: Yew belly grain
« Reply #12 on: November 25, 2019, 10:51:12 am »
Let me finish my coffee and get the shop warmed a bit, cold here this morning. Then I'll take some pictures. I'm thinking PatM's idea is what I'll go with. I'm sure a patch like Del suggested would be good but I'm not good at inletting unless it's a flat surface. Curved just kills me. A little confession to make, I've already put on a belly lam because this same limb was giving me problems earlier so it's already a dogs breakfast. My plan this second(could change ;D) is to continue tillering to see if I can rescue this and still keep it above 35#. If that fails I'll grind it down and apply a new belly. Pictures in a bit first.
Vancouver Island
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Offline Del the cat

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Re: Yew belly grain
« Reply #13 on: November 25, 2019, 10:58:11 am »
Let me finish my coffee and get the shop warmed a bit, cold here this morning. Then I'll take some pictures. I'm thinking PatM's idea is what I'll go with. I'm sure a patch like Del suggested would be good but I'm not good at inletting unless it's a flat surface. Curved just kills me. A little confession to make, I've already put on a belly lam because this same limb was giving me problems earlier so it's already a dogs breakfast. My plan this second(could change ;D) is to continue tillering to see if I can rescue this and still keep it above 35#. If that fails I'll grind it down and apply a new belly. Pictures in a bit first.
Hmm... maybe the weakness is in the back?
Del
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Offline DC

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Re: Yew belly grain
« Reply #14 on: November 25, 2019, 11:09:27 am »
It's a Bamboo back, it "should" be good.
Here's some pictures. The last one is about 26#@17"
Vancouver Island
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