Primitive Archer
Main Discussion Area => Bows => Topic started by: Selfbowman on March 05, 2017, 03:33:08 pm
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Guys I am building a bow from a very good Osage stave. I started at fades 1/1/2" width and went from there to 1/8 " at tips. The bow is 67" in length with a 10" ridged handle. I chose to tiller the belly in a pyramid. I did this forming a straight line down the center of the limbs , then penciling the sides of the limbs about a 1/4" from the back . Then took out wood between the lines. This bow is at probably 70-80 pounds right now. I will try to load a pic. My ? Has anyone built a similar bow and what the outcome was far as set, tiller suggestions welcome, I will round the edges at last 2-3# trying for a 50# bow.
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Well as usual iPhone and iPad don't want to connect. Try sending on iPhone .
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Try 2
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Try 3
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It's a wonder I ever built a bow . :BB
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Ok
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Looks like more or less the same thing but expecting different results. ;)
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Well a little different. The belly is not flat or d shaped. It is one continuous decrease in widths instead of parallel to mid limb but yes very similar. I am trying to decrease mass as even as possible while playing with the tension and compression without risk of to much set. That's what we all do I think. Any how I will finish it when the moisture goes from 10 to 7 percent.
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my only thought is the compression forces concentrated on a peak could cause fretts.if I understand correcly?
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Ok that's not good! Arvin
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I've never considered a pyramid design on an osage bow because it's so important to follow the grain. If I want it to taper more in width, I start with a generous thickness and gradually reduce width as I follow the grain from the handle out to the tips. I'd be afraid to draw straight lines and cut along them. I try to let the grain do most of the work with osage.
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Upstate I get that grain straight before it's laid out. This was a good stave and I rough out the bow 1-3/4-2" off of a split. Then rough out the belly and fades. Now I straighten the roughed out stave-bow. Then I lay my bow out . As of late . I study the grain after my back is almost finished if I need to alter the rough out some I still can . Meaning bring tips off center of rough out to follow grain. Then back to heat bench to put reflex or what ever else you want to do to the bow. Then I Finish from back to belly. I also know you can't get this with ever Osage stave. Knots, bends ,kinks and such can make for a real challenge of the whole process. I have been using the best wood I have as late. I've done the other you spoke of . On a mission. :BB
Arvin
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It seems to me that one of the cross section's in laubin's book or one of the bibles shows that peaked belly
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Yes Bubby me to. I was just curious to find out the out come. I am pretty sure I won't ever come up with something that has not been tried in the last 5000 years. Arvin
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Arvin i haven't done a whole limb like that but i have been doingwith a peaked belly in the lever sections that work just a bit, no problem so far
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Laubin's book shows that in an Eskimo bow although no cable is illustrated.
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Sorry Arvin, I should have read your post more carefully. :-[
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Upstate no problem . I don't explain myself clearly anyway. Arvin
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New pic
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Well it took set from mid limb to fades. I got some mass off at a price. The bow weighs 19.5 oz with a 9" handle 67 " ntn, 46-27. I have shot 4 arrows thru it but they seemed fast and smooth for sure no shock. Moister meter said 7% but my gut says its higher. The flattened v shape lightened the load but gave me set as Pat and others thought. It was too dark to crono or flight test so not sure about that yet. Arvin
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Do you ever just trap the back?
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Pat I have tried D bellys, flat with trapped edges, real symmetrical flat limbs the same thicknesses. I have gone from 1-1/4 to 1-1/2 at fades to 1-1/2 to 1-1/4 at mid limbs , all tapering to 1/8 -1/4 at tips. I know every piece of wood is going to be a bit different. God planed it that way in us and the trees I think. But my goal is to find the perfect mass placement for as little set as possible as light as possible on the ends. Can't do the math but pretty sure there lies my answer to my quest. All from Osage and from 67-69 in length. Some with 10" handle . This one is thicker at the fades to thinner at the tips v shaped somewhat. The limbs are one continuos decrease in width. Which makes midlimb right at one inch in width. No I have not trapped the back. Other than rolling the edges say 1/4 " in or so. Arvin
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Arvin, just curious how long ago was that stave cut? To me it seems the older the better at least 2 years.
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2 years or more with with osage and roughing it out along the way is even better!
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Bob 1-1/2to 2 years I would guess. It must have came out of a big tree. It was a belly split about 3to3-1/2 " across the back. Pretty flat , even rings , no knots , very little propeller in it. Good stave. The kind you would like to know where to leave the mass and where to take it off. :BB Arvin
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Pat tell me about trapping the back and its benefits if there are any. Arvin
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It makes the back work harder because there is less wood doing the tension work. It is a technique best saved fro tension strong/compression weak woods. Like ash, red oak, hickory etc. I have never found an osage stave yet that would benefit from it. Osage is one of the 'best' woods because the tension/compression strengths are very well matched, it is also very elastic. Maybe if you had a dead flat backed stave it may help slightly to trap the back but really all you would need to do is radius the corners.
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Ok Mike I would say that we still don't go thru the growth ring on the back. Or violate it evenly thru out the length of the limb on the edges? Or use a sapling - high crown back? Is the trick to keep the tension - compression even thru out the limb width even though it gets thinner on the outter edges of limbs? I have wood that I can do all these with. Remember going for no set. The BB recommends flat backs for best tension and flat bellys on Osage. The problem is getting the extra mass off and where it should come off . I know off the ends if possible. Steve told me extra inner limb mass is not as important as on the ends . That makes perfect since to me. Finding that happy medium with no set is the secret I would say . If I succeed with this it's only because one I am hard headed and determined to do something that's near impossible. Two cause I don't know any better. And three I have to much time on hand. I don't think it's the latter. Arvin
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Mike I have built some dead flat back bows and rolled the edges slightly. Two took hardly any set at all but the mass was still on the slightly heavy side. They had great cast but come up short. Lol Arvin
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Arvin,not to discouraged, I believe that Simpson concave belly would reduce mass and keep the set to a minium.
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It's a wiley rabbit chasing what your chasing Selfbowman.Seems to me building here if my handle is smaller [i use a bulbous type]with only 1.5" fades my mass gets lower quite a bit.Sometimes too abrupt rise in the fades to handle though.
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Well that rabbit was slow! ;D. 163 fps 180 yards 46-27 500 gr arrow. A good smooth no shock bow but no super bow. Arvin
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You'd almost have to have a few staves from the same tree to be really really diagnosing properly woul'nt ya?I don't blame you for wondering about those traapped backs since saplings seem to be kinda spryer most times for some reason,but ya osage is the best balanced wood out there that I know of.Kuddos to ya for trying.
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I think its shooting good for the profile it holding,, sure would kill a deer :-D
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That wasn't bad performance at all. maybe not a competition bow but still very respectable. If you would have drawn it to 28" it would have hit 170 and 200 yards.
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nice job. This is an interesting thread... and that is a nice bow.