Primitive Archer
Main Discussion Area => Bows => Topic started by: Fox on June 12, 2021, 01:50:41 pm
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I’m working on a 2 inch diameter sapling stave. Floor tillering it now, the problem is it’s only 1 1/2” wide now and worried it’s going to start getting smaller soon because of the high crown. How is this dealt with? It’s hickory 64” long.
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You let the bow be what it’s gonna be width wise. You can’t impose what you want onto it, cause as you tiller the thickness, the width drops a little. The edges are gonna get sharp as you’re tillering it, blunt that edge cause it can give you problems later. That will also reduce width.
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Only way would be to keep it long/let it bend through the handle. Keeping the bend radius of the limbs as big as possible will keep it as thick as possible.
I suppose some people do hollow limbs but I’m not as familiar with the behavior of those bows.
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in the high crown staves that i've made (and i like them) you can't dictate the profile pretty much at all, Morgan has good advice let it be what its going to be and keep the edges rounded over so you don't get into trouble, i'll also ad that you should have your tiller pretty close by the time you get to brace as i've found that for me high crown staves drop weight fast.
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Dylan is right about dropping the weight fast, didn’t think about that. I typically get saplings to brace and then heat treat them good. Didn’t think about the HLD as an option either. I think the saplings peculiarities is why most of the eastern woodland bows are almost identical in design and dimensions. I think this style bow is near perfect for saplings. Last sapling bow I made was from a 2” tip diameter after bark was removed American elm. It was 62” long and 52# at 28. Wound up being pretty much 1 1/4” wide most of its length before tapering to the tips. I could have squeezed out 1 3/8” wide limbs maybe but wouldn’t have the amount of meat on the limb edges that I’m comfortable with. I have better luck with narrow limbs on saplings not taking a ton of set or fretting than I do wide staves. That may be because of the high crown or something else, I don’t know for sure, I just know it works for me. Saplings seem to be quite tough.
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why not tiller from the back ? you seem to have just the right species for decrowning as sawn hickory is often reccomended for backings.
If you are concerned about ring violations you might consider a prymid width profile as it will minimize thickness tapering. or you could decrown prior to tillering such that the flat on the back shows straight ring lines (following the dips and humps the best you can) then follow up with some thickness reduction belly tillering if you like the eastern woodlands width profiles
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Love high crowned Osage. Can’t speak to Hickory, but with Osage, they take less set, so long as you can keep the back together. Narrow and longish.
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I've only done osage also. It makes a hard hitting bow. They generally bend in the handle so I make a handle out of thick leather so it can give without popping off.
Be sure the center pith has been remover or the wood usually checks along the pith.
For a 2" osage "pole", I saw it lengthwise and bind the halves back together with cord and small wood spacers between the halves to allow for air movement. I've made bows of up to 55# with 2" osage. Also, with osage I usually backed with rawhide for protection.
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I'm currently working a bl. walnut sapling stave that's about 1.5" wide after floor tiller. To keep from further shrinking the width I'm planning on using the curved scraper to HLD the limbs. In the case of the walnut I also have the issue of the pithy center, floor tillering (currently flat across the belly) cut into the pith in some areas and is only a few scrapes away from breaking into the pith in others. HLD will let me keep the width where it is and scrape out the pith. But, I've never tried HLD before so take this suggestion with a grain of salt.
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Thanks for all the great advice guys! think ill make it bend thru the handle...
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why not tiller from the back ? you seem to have just the right species for decrowning as sawn hickory is often reccomended for backings.
If you are concerned about ring violations you might consider a prymid width profile as it will minimize thickness tapering. or you could decrown prior to tillering such that the flat on the back shows straight ring lines (following the dips and humps the best you can) then follow up with some thickness reduction belly tillering if you like the eastern woodlands width profiles
I thought about decrawning, but this stave has some pretty good-sized knots in it.... if I recall you can't decrown with knots?
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one if the problems that happens with a high crown back, is when there is a knot in the middle where the stave is the thickest and the stress is the highest. a place for the stress to concentrate. with a decrowned back, one might hope for a wider area without imperfections, and the potential to spread the stress out across more sound wood.
you could post a pic and you might get a good discussion going. :) I have not seen decrowning done a lot on self bows but know of no reason not to give it consideration.
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I usually start hollowing the limbs at this point, you don't need to go full hollow limb but you can reduce mass this way
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I've only built a couple bows from small diameter trees and have some staves drying so I'd be interested in a good conversation on the subject. I've read in TBB that the point becomes unused mass so I always try to eliminate it. I've thought about decrowning but the never worked up the nerve to try it. I think if I did I would back it but not sure it's necessary
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Decrwoned staves are the easiest but best boards for bow making. They are often better than pristine back staves. Much better for beginners.
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...as long as the grain lines run parallel with the limbs.
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Decrowning is an option I suppose. Not one that I am generally in favor of. That's just me, others may have different preferences. With a flat back the stress along the back is felt more evenly across the width, so more strain on the belly. With a crown, most of the tension is felt at the top of the crown. The lower edges are just along for the ride. If you have a wood that is tension strong, which Hickory is, it can better withstand the strain on the back along the narrow crown. That means I can go more narrow and thick (lighter) than I could on a flat back, so long as I go long enough to keep the bend radius moderate. Less strain on the belly so less set as a consequence. This would be my argument in favor of leaving it crowned.
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Many people, including me, routinely trap the back of hickory staves or boards.
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Trapping creates a crowned back. So we agree?
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Decrowning is an option I suppose. Not one that I am generally in favor of. That's just me, others may have different preferences. With a flat back the stress along the back is felt more evenly across the width, so more strain on the belly. With a crown, most of the tension is felt at the top of the crown. The lower edges are just along for the ride. If you have a wood that is tension strong, which Hickory is, it can better withstand the strain on the back along the narrow crown. That means I can go more narrow and thick (lighter) than I could on a flat back, so long as I go long enough to keep the bend radius moderate. Less strain on the belly so less set as a consequence. This would be my argument in favor of leaving it crowned.
This makes sense in theory but what would you guess is the actual thickness difference you can get between a rectangular and crowned/trapped cross section? I would guess it’s very small from a practical standpoint.
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I would agree with that Ryan. I too think the difference in thickness would be minimal, but I think the difference in weight could be more significant as a result of it being more narrow. The bow belly being strained less adds to these other small benefits, and in the aggregate you get the more significant benefit. This would be my argument, not just from a theoretical position, although the theory is sound, but from an empirical, practical standpoint, as the bows I have made from crowned staves have had better cast.
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Here's the way I do it.
http://traditionalarchery101.com/saplingbow.html
Jawge
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I feel like The mass gain is a wash when you’re dealing with 2” and less saplings. My last sapling bow is a loose interpretation of an eastern woodlands bow in the low 50’s draw weight. 62” tip to tip made from an American elm that was 2” dia. The bow wound up being 1 1/4” wide by the time I got it tillered and was comfortable with the amount of meat on the limb edges. Most on here would want the bow limbs to be at least 1 1/2” wide and some would say 2” + for that length. If it was made of a same species 2”wide board I’d bet the mass would be darn close to what it is now, if it was the exact same style being parallel limbed out 2/3 then tapering to 1/2-5/8” nocks I believe the board may even have more mass. The bow took an inch of set in the form of lost natural reflex, still has around 3/4” reflex and has been thoroughly shot in. I don’t claim to think this is the best design out there but you can get a hell of a lot out of a little bit of wood, and my experience playing with tension strong saplings makes me question the bad reputation they get due to having a high crown. I am of the notion that saplings is the reason most of the eastern woodland bows were designed the way they were. If you take a sapling and split it and start whittling away wood to an even bend, that is just what you wind up with. I like to start my limb taper a little earlier than on most examples and definitely wind up with more narrow nocks though.
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I’m not one to weigh my bows, so I can’t say for certain that I’m right, but I would think that the crowned stave bow will be lighter than it’s board bow counterpart, all things equal, more often than not. I too like the style you described, and with the right stave, crowned with reflex as a starter, they are hard to beat. The 2” wide board bow you mentioned above would have more mass than your 1.25” bow IMO.
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I’ve never weighed one either, I guess from a scientific standpoint my opinions hold little merit ;D. For that matter all the bows I have to make comparisons to save one was made by me so that diminishes my scientific view further. I just like to make a tree launch a smaller tree lol (SH)
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I’ve never weighed one either, I guess from a scientific standpoint my opinions hold little merit ;D. For that matter all the bows I have to make comparisons to save one was made by me so that diminishes my scientific view further. I just like to make a tree launch a smaller tree lol (SH)
(lol) (lol) (lol)
I love it when these good discussions get going :).... im soaking it all in ;D
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I hear ya. I make these bows mostly by feel. How do I feel about the stave quality, length, width, etc…I lean on all who HAVE done the the research, certainly, and I find the more technical aspects fascinating, but I can build self bows without any of it. Just horse sense.