Author Topic: Sinew backing: to chase or not to chase?  (Read 1179 times)

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Offline bassman211

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Re: Sinew backing: to chase or not to chase?
« Reply #15 on: January 24, 2023, 10:05:05 pm »
Been using marginal staves for years when using Osage, and others woods, and for me it works great with a sinew back.  I don't get to many primo Osage staves. When I do get one I make a self bow. Every thing I read about sinew, and juniper is positive, and your right Ishi never worried about back violations. I would sinew back it ,and shoot it.

Offline Selfbowman

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Re: Sinew backing: to chase or not to chase?
« Reply #16 on: January 25, 2023, 09:23:09 am »
I follow the growth ring on the back even when I bamboo back the bow. Do you need that to save the back no. But I feel it helps have one or maybe two growth rings on the belly not violated . Does this matter maybe not but for me it spreads the compression load more even. Some will probably say Iím nuts but whatís new.
Well I'll say!!  Osage is king!!

Offline joachimM

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Re: Sinew backing: to chase or not to chase?
« Reply #17 on: January 25, 2023, 02:48:28 pm »
For what it's worth: backing a bow with any material moves the neutral plane closer to the the back of the underlying wood. If you're adding a lot of sinew, the actual underlying wood is much less strained in tension, as most will be in compression. So that allows you to have a violated back. To what degree that's safe will depend on the wood being used, the amount of violation, the amount of backing...
If it's just as you described some bumps and valleys that would be cut through on a decent juniper stave, I wouldn't mind that. I've decrowned a few elm staves and backed them and never had issues other than chrysals on the belly, meaning the wood was eventually too weak in compression.


Offline bradsmith2010

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Re: Sinew backing: to chase or not to chase?
« Reply #18 on: January 26, 2023, 04:01:19 pm »
did you mean further away from the back,,?

Offline Marin

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Re: Sinew backing: to chase or not to chase?
« Reply #19 on: January 27, 2023, 02:21:59 am »
I probably should also attach another photo, as I've described this but am not sure if I described it well enough. Bascially, when I mention decrowning, I don't just mean that I violated all of the back equally (as you're supposed to do when decrowning a stave for a flat bow). I decrowened it overall but in some places shaved it down a bit more than in others to give the back a uniform shape. I see this in a lot of the originals (like I said previously, I never have seen a western sinew backed bow that was snaky or preserved the orignal crown shape) but it does mean that when I am talking about a violated back, I mean a back that is overall largely unviolated or where the violation fairly limited and then one or two small spots where the violation is quite strong. It's what happens when you flatten these hills and bumps on juniper, and with rings being so close together, it's far more apprent.
But from this conversation, it sounds like if I am correct overall with how I understand sinew, especially on a soft confier wood like juniper or yew, that this degree of violation in only one spot still shouldn't provide a problem? I know I am probably being paranoid like I usually am and I am not giving up on this stave for the moment (I spent the last bit of time recurving it, floor tillering it and still getting the sinew ready).

Offline Marin

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Re: Sinew backing: to chase or not to chase?
« Reply #20 on: January 27, 2023, 02:25:52 am »
Sorry, photo didn't upload properly....

Offline bassman211

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Re: Sinew backing: to chase or not to chase?
« Reply #21 on: January 29, 2023, 09:50:26 pm »
A couple months ago  I built an Osage self  bow 45 lbs. at 25 inch draw 58 inches long that had a cluster knot on the back. I did not violate  the knots as I wanted a self bow. It lifted a splinter at the knot cluster, so  I opened up the splinter, and soaked it with crazy glue, and wrapped it  with hide glue soaked sinew. So far so good, but had I sinew backed it their would be no patch. JMO