Author Topic: Advice on yew flatbow with high crown and thick sapwood  (Read 425 times)

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Offline Whiskeyjet

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Advice on yew flatbow with high crown and thick sapwood
« on: February 26, 2020, 02:55:32 pm »
So, I'm starting on a yew stave I got from High Desert a couple years ago, and finally feel ready to give it a shot.  64" long, and I've roughed the width out to about 1.75" for now.  I'd like to flip the tips and get 50-55lbs at 27".  The dilemma i have is how to deal with the sapwood.  it is about 3/8" thick, but with the crown and the width of the limbs, the sapwood is reaching the belly at the edges, and the stave isn't even that close to floor tiller, about 1" thick from crown to belly.  What's the best way to deal with this? Decrown? Thin the sapwood all over? Go narrower?  All three?  I plan on backing with sturgeon skin.

Offline Hamish

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #1 on: February 26, 2020, 03:04:33 pm »
Post a shot of the end grain to show how high the crown is, whether the heartwood reflects the same shape.

Offline High-Desert

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #2 on: February 26, 2020, 03:15:22 pm »
Thin the sap the 3/16Ē or so, half of what it is now, and you can also narrow it a bit to 1-1/2Ē, but start with thinning the sapwood and you can narrow down the road.
Eric

Offline Weylin

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #3 on: February 26, 2020, 03:48:37 pm »
You can reduce it but be careful to follow the crown faithfully when you do so. It's easy to dig all the way through to heartwood when it's crowned like that. I'd reduce it to 1/4". Don't worry about the sapwood wrapping around the side. It wont hurt anything. Just keep that sapwood layer as consistent as you can across the width of the back. What's important is that there's a solid core of heartwood going through the bow. That's what's doing the work. You wont necessarily have that lovely contrast between the sapwood and heartwood running down the side of your bow but that's just the reality of high crowned yew. Another option is doing a hollow belly to match the contour of the crown. It's more tedious and a bit trickier so if it's you're only piece of yew to mess around with for the forseeable future and you're not feeling super confident then I'd stick with a traditional cross-section.

Offline Del the cat

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #4 on: February 26, 2020, 03:52:57 pm »
Decrowning isn't too much of a problem as you'll see the exposed rings running along the length of the limb, that way you can achieve a genlly crowned back. Sapwood wrapping round the sides onto the belly can look great, giving a nice coffee and cream look. Or reduce the width until it's just heartwood showing on the belly.
My go to field bow is like that, decrowned and width reduced.
Del
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Offline Weylin

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #5 on: February 26, 2020, 03:55:00 pm »
Decrowning isn't too much of a problem as you'll see the exposed rings running along the length of the limb, that way you can achieve a genlly crowned back. Sapwood wrapping round the sides onto the belly can look great, giving a nice coffee and cream look. Or reduce the width until it's just heartwood showing on the belly.
My go to field bow is like that, decrowned and width reduced.
Del

Especially if you're backing with Sturgeon skin. That stuff is tough!

Offline Whiskeyjet

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #6 on: February 26, 2020, 04:29:52 pm »
Decrowning isn't too much of a problem as you'll see the exposed rings running along the length of the limb, that way you can achieve a genlly crowned back. Sapwood wrapping round the sides onto the belly can look great, giving a nice coffee and cream look. Or reduce the width until it's just heartwood showing on the belly.
My go to field bow is like that, decrowned and width reduced.
Del

So if I have sapwood on the belly, do i need to have a lens cross section? I need heartwood doing the compression, don't I?  Or is sapwood ok at compression with yew?  I've always heard that all heartwood can make a bow, but an all sapwood bow wouldn't work.

Offline Whiskeyjet

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #7 on: February 26, 2020, 04:35:49 pm »
You can reduce it but be careful to follow the crown faithfully when you do so. It's easy to dig all the way through to heartwood when it's crowned like that. I'd reduce it to 1/4". Don't worry about the sapwood wrapping around the side. It wont hurt anything. Just keep that sapwood layer as consistent as you can across the width of the back. What's important is that there's a solid core of heartwood going through the bow. That's what's doing the work. You wont necessarily have that lovely contrast between the sapwood and heartwood running down the side of your bow but that's just the reality of high crowned yew. Another option is doing a hollow belly to match the contour of the crown. It's more tedious and a bit trickier so if it's you're only piece of yew to mess around with for the forseeable future and you're not feeling super confident then I'd stick with a traditional cross-section.

I have tried a walnut HLD bow just for giggles, it shoots (slowly lol) but I don't want to go for it here, even though its probably a perfect candidate for doing one. Yew doesn't grow on trees out east ;)

If I reduce the sapwood, can I get away with feathering it back out at the handle? I'd like to maintain thickness if possible there. 

I know you've done a lot of sturgeon skin backings, at what point do you usually put them on? Mine has been sitting a while (dry in a shoebox), do they go bad at all?  The guy I got it from said it would keep and didn't need to go in the freezer (where I keep snakeskins until I need them)





Offline Weylin

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #8 on: February 26, 2020, 04:48:24 pm »
You could feather it out at the handle. I don't think that would hurt anything. I treat sturgeon skin just like rawhide except I wash it with dawn detergent before I put it on to make sure there's no residual grease on it. You could put it on sometime during the tillering stage if you wanted, but here are a couple reasons I wait. First off, I want to be certain I don't need to do any more heat corrections before I add any skins. It's hard for me to know that if the bow hasn't been tillered and shot. The other reason is that, for me,  rawhide and sturgeon are just a little added insurance. I don't like to rely on them to trust the bow. I'd like to know that the bow can go out to full draw and shoot some arrows on it's own merit before I back it with something substantial. I don't follow that rule 100% of the time but I always feel better about a bow if I know it's not relying on this little piece of skin to hold it's soul together.

Offline Whiskeyjet

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #9 on: March 13, 2020, 01:18:28 pm »
Well, I'm intrigued enough with the idea of having some sapwood on the belly edges, but am also going to decrown it a little to make sure the edges don't get super thin.  Now since I'm backing it with the sturgeon skins, what do I do at small knots on the back? there are a couple dead on the crown, or near enough to be involved in the process.  So do I treat them with TLC (how?) or mow em down and maybe put a thin layer of sinew over it before i put the sturgeon skin on?

First off, I want to be certain I don't need to do any more heat corrections before I add any skins.

Weylin, when you say this, do you mean like getting tip alignment correct? Are there other things you heat treat for during tiller?

Offline Weylin

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #10 on: March 13, 2020, 03:13:59 pm »
I'd blow right through those little knots with the drawknife when reducing the sapwood. If it was a more substantial know I might consider leaving it proud but not pin knots.



Weylin, when you say this, do you mean like getting tip alignment correct? Are there other things you heat treat for during tiller?

Yes, get the alignment settled before skins. Do any reflex to the tips, correct any areas of deflex, etc. If it's a straight stave with no issues then it probably wouldn't hurt anything to do it sooner. I like to hold off on backing a bow until I really feel like I need the tension support. With a stave like that I'd probably do it after I got it braced with a good tiller. A lot of my backed bows I have them shooting before I back them but I trust yew with the sapwood reduced a little less so I'd back it sooner.

Offline Whiskeyjet

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Re: Advice on yew flatbow with high crown and thick sapwood
« Reply #11 on: March 13, 2020, 03:42:17 pm »
Thanks Weylin, really appreciate the guidance. Yeah itís a reaaaaally nice stave IMO. Pretty much pipe straight. I flipped the tips a tiny bit but I donít plan on doing anything beyond whatís necessary beyond that.