Primitive Archer
Main Discussion Area => Bows => Topic started by: Marin on January 10, 2023, 01:21:56 am
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Hey Guys,
So this is something I have heard different answers on. I have heard some on this website advise chasing a ring before sinew backing as even sinew won't make up for a violated back, depending on the level of violation. I have heard others however that completely cut through the back and not even care about the amount of violation that happens to the back, caring more about the eveness of the shape of the back rather than how much is violated. Both of these types of people make great, durable sinew backed bows so I do not doubt their expertise. I am just wondering if perhaps their opinions are influenced by other factors. Consulting ethnographic accounts and archaeological evidence out west, where these bows were made, I have heard of staves that were debarked and sinew applied to what was the outer portion of limb itself, and others that were heavily shaped and rounded over. Ishi did this, and I even saw a video of an old Yurok bowyer who takes a yew branch, turns it into a rough board before making it into a lenticular cross section bow, so clearly a lot of violation going on.
And honestly in making these bows, I just don't see how you can make them without some sort of violation. For example, I am working on a very good, knotless but narrow juniper stave and have taken time to get the lateral grain violations to a minimum through heat straigtening to get out all warping and such. But shaping/decrowning the back on close grained juniper, its impossbile not to violate, esepcially when juniper has these micro "hills" and contours that need to be accounted for. I understand primitive peoples were probably far more selctive, but Western bows often have such perfect shapes and contours, I find it impossible that they left their backs as is, and as I said before, accounts I have seen seem to agree with me.
Do you guys think that certain woods, especially juniper and yew, seems to handle this violation better than others, like osage and hickory, which is why sinew backed bows made from these bows have a lot more flexibilty in form and shape (ie you can shape the back any way you want)? It seems to be the only correlation I find when seeing different answers from different bowyers. Perhaps is it reducing lateral grain violation through heat straigtening and the like more important in the durability of a sinew backed bow?
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I would approach it as such. If its a wood, such as yew, that will allow violations and still be a self bow then I wouldn't worry about it. If its a wood, such as osage, that must be on one ring then I would be on one ring prior to adding sinew. Its not right or wrong, its just my way. The worst kind of bow you can build is the one that makes your butt cheeks tense up at full draw.
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Is juniper also the same way though? I have heard of some juniper self bows where the grain had been violated on the back but I haven't seen them myself....
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I cant speak for juniper as I've never used it. Although, I believe it to be the same as yew in that regard. Some forms of violations are mostly okay on a self bow.
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If I may pick your brain, do you know why it is that lighter conifers like juniper and yew can handle this? All I can think is that it has to do with the fact they are closed ringed, but I conceptually am a little confused
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im just guessing, but alot would depend in the draw weight and how far you intend to draw the bow,,as to how much violation it would take,,
differnent woods are just different,, Im pretty sure Jim Hamm recommended following a ring, thats how I did it most the time on osage,, but sometimes if the stave was not enough to make a bow I made successful bows with violated back,,thinking a couple extra layers of sinew would work,, and did,, there may not be a definitive answer,, and lots of variations may work,, I like the way Pearl looked at it for a good starting point,,
try it both ways and see what you think,, keep notes and give good advice later when someone has the same question,, :)
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Okay will do. Thanks, I just wanted to make sure I wasn’t the only one who thought there was more “nuance” to this
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Back violations is the only reason I ever sinew backed a bow. If I have a clean back ring I don't sinew back it. No need. No failures yet with violated backs, and sinew, and not at all gun shy to shoot them, but do it the way you feel most comfortable. Never used yew, or juniper. I have used blue beech ,elm, black locust, Osage, and hickory with violated backs ,and sinew with 100 % success rate so far.
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I have had success with slight violations in non critical areas on whitewoods with backing with rawhide. In cases where I have to remove surface damage or just shaping into the right thickness for the weight of draw I want I’ll sinew back and also thin rawhide or snake or fish skins. For yew I’ve gotten lucky with slight violations of the sapwood but I think bow design would be a factor too. Like was said already most non rawhide skins other then maybe sturgeon offer only cosmetic covering to the bow back and won’t provide any strength really.
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. I’m not certain on the real reasons, but aside from yew and juniper being evergreen soft woods, and osage being a hardwood, there’s pretty big differences in the wood and why most keep a single ring for osage and violate yew and juniper. There’s not a big difference between the early wood and latewood in yew and juniper, probably because they grow all year round. I prefer to use pretty nice and clean wood for sinew bows, so violations are minor anyways.
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Yes I was using pretty good wood already, but the design I was trying to make called for an even and slightly flattened back with required me to cut through some contours in order to make the back far more uniform and violate the grain more so in some places than others
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If the bow you plan on building requires a flat back, decrown the stave properly, with the ring edges running parallel with the bow. I believe it's the ring edges that run across or diagonally across that lift the splinters resulting in a BANG!
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Yes I understand proper decrowning but I should say this wasn’t exactly a proper decrowning. As its juniper, it often snakes or has uneven crown through its length, so I couldn’t really section it like say a straight piece of elm or hickory.
Since I’m backing it with three layers of sinew though, sounds like that shouldn’t matter.
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Sinewing is a lot of time and work involved. When I sinew back a bow I want the best piece of wood I can get and prep it to the best of my ability. If you want to make a sinew backed bow don't use a marginal stave to start with. I think even snaky staves can be decrowned if you follow the lines of the bow with the decrowning.
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This wasn’t a marginal stave or bad. It was a tight grained piece of Utah juniper. In working with juniper, I’ve only found that juniper has these little features, contours and bumps just because of the way it grows, even the best pieces will have wierd crown or grain deviations.
I get what you are saying, but it just seems like it is still possible to make a great sinew backed bow even with a piece of wood that breaks some of these rules. As I mentioned before, Ishi and other west coast tribes completely cut through rings and ignored grain violations (though they did select straight grained and mostly knotless pieces of woodJ and they made pretty durable backed bows with it. And I’ve yet to see a super snaky west coast juniper bow or one where the back clearly followed the original crown of the wood or was der owned properly, it seems like regardless some rules have to be broken just to make these bows.
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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.
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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 I’m nuts but what’s new.
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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.
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did you mean further away from the back,,?
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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).
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Sorry, photo didn't upload properly....
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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