Primitive Archer
Main Discussion Area => Bows => Topic started by: mmattockx on March 18, 2020, 01:13:47 pm
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My next project is going to be a red oak board pyramid bow. I am thinking 66"-68" NTN, 35lb draw @ 28". From reading TBB V.1, I understand that 2" wide at the fades would be lots for my length and target weight.
1) Is 2" tapering to 1/2" at the nock going to be enough taper to tiller as pyramid bows usually do? Do I just work the limb thickness as required to get the circular bend that pyramid bows are supposed to have, regardless of the taper?
2) Will the limb actually stay at a fairly constant thickness with such a minimal taper?
Thanks,
Mark
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A true pyramid would go to needle tips and that width taper would give you a true circular tiller.
The 'extra' width at your tips means that you will end up with a slight thickness taper, with the bend increasing as you progress along the limb (just a bit).
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A true pyramid would go to needle tips and that width taper would give you a true circular tiller.
The 'extra' width at your tips means that you will end up with a slight thickness taper, with the bend increasing as you progress along the limb (just a bit).
Well, I can live with that.
Thanks for the reply,
Mark
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I understand that 2" wide at the fades would be lots for my length and target weight.
could be if you have a straight grained dense boarded. TBB4 P115 has info for density vs width in that length and a simple method to determine density. making a few tests beforehand helps, or you could switch to side tillering some excess width if you see your limbs getting too thin.
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I imagine wider at the fades would work with a shorter bow for draw weight?
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What bownarra said.
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I make my pyramid Osage bows wide as the staves allow . Inter limb mass is not as critical as otter limb mass. Most are 67-69" long . The bowyers bible calls for 1-5/16" in width on the density chart I think. The extra with seems to help me in tillering low set bows. So 2-1/2 inches won't hurt you. Use 1" of limb for every inch of draw. It's a good recipe. Arvin
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I've made quite a few red oak pyramid board bows, and I like them. 2in wide tapering to .5in should work out pretty well. Just make sure its an actual 2in wide, and not the measurement listed on the board at the big box store, those are only 1.5in. Those still work, but I prefer a bit more width than that.
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you will end up with a slight thickness taper, with the bend increasing as you progress along the limb (just a bit).
so for a circular tiller you would need no taper or a slight reverse taper?
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So 2-1/2 inches won't hurt you. Use 1" of limb for every inch of draw. It's a good recipe. Arvin
You don't think I would end up with really thin limbs that way for a 35lb draw weight? The 30lb maple mollegabet bow I am finishing is only 1.5" wide and the working limbs are around 1/4" thick up near the levers. They look scary thin to me.
I've made quite a few red oak pyramid board bows, and I like them. 2in wide tapering to .5in should work out pretty well. Just make sure its an actual 2in wide, and not the measurement listed on the board at the big box store, those are only 1.5in. Those still work, but I prefer a bit more width than that.
It is a nominal 1x3, so is 0.75"x2.5" in reality. Maybe I will go with 2.25" near the handle just to be sure. The grain is not quite dead straight on this board and I plan to skew the centerline of the bow to better match the grain, so 2.25" is probably as wide as I can go anyway.
so for a circular tiller you would need no taper or a slight reverse taper?
If I understand him correctly it is the other way and it needs a bit thinner tips than at the base of the limb. Because the tip doesn't go to a point there is extra material out there and that makes it a bit stiffer than a theoretically perfect triangular limb profile.
Mark
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This post answers the questions about thickness taper :)
https://bowyersdiary.blogspot.com/2014/12/pyramid-taper-test.html (https://bowyersdiary.blogspot.com/2014/12/pyramid-taper-test.html)
Del
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I've made quite a few red oak pyramid board bows, and I like them. 2in wide tapering to .5in should work out pretty well. Just make sure its an actual 2in wide, and not the measurement listed on the board at the big box store, those are only 1.5in. Those still work, but I prefer a bit more width than that.
It is a nominal 1x3, so is 0.75"x2.5" in reality. Maybe I will go with 2.25" near the handle just to be sure. The grain is not quite dead straight on this board and I plan to skew the centerline of the bow to better match the grain, so 2.25" is probably as wide as I can go anyway.
I like your idea, I don't think you'd need to go wider than 2.25 anyways. I think you are setting yourseld up for success.
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Del that answers all the main question for sure
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This post answers the questions about thickness taper :)
https://bowyersdiary.blogspot.com/2014/12/pyramid-taper-test.html (https://bowyersdiary.blogspot.com/2014/12/pyramid-taper-test.html)
Del
Thanks for that, it is very helpful.
Del that answers all the main question for sure
It sure does, that clears the question up very well. I find it pretty surprising that it tillers semi-circular no matter the taper ratio or thickness as long as the taper is to a point and the thickness is constant. Math and mother nature are sometimes amazing that way.
I like your idea, I don't think you'd need to go wider than 2.25 anyways. I think you are setting yourself up for success.
I like to hear that, thanks.
Mark
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This post answers the questions about thickness taper :)
https://bowyersdiary.blogspot.com/2014/12/pyramid-taper-test.html (https://bowyersdiary.blogspot.com/2014/12/pyramid-taper-test.html)
Del
Thanks for that, it is very helpful.
Del that answers all the main question for sure
It sure does, that clears the question up very well. I find it pretty surprising that it tillers semi-circular no matter the taper ratio or thickness as long as the taper is to a point and the thickness is constant. Math and mother nature are sometimes amazing that way.
This is why I say that once you make a pyramid bow, you may see little reason to ever make anything else. I have seldom made another style in at least 20 years.
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This is why I say that once you make a pyramid bow, you may see little reason to ever make anything else. I have seldom made another style in at least 20 years.
I can understand that, the simplicity and ease of tillering are appealing. I like recurves, too, though. Ever made a recurve pyramid bow? High-Desert posted one last March with flipped tips that piqued my interest on that idea.
http://www.primitivearcher.com/smf/index.php/topic,65382
Mark
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This is why I say that once you make a pyramid bow, you may see little reason to ever make anything else. I have seldom made another style in at least 20 years.
One more question comes to mind - how do you get down to an even thickness for the full limb length on a pyramid bow? I am stuck with board bows for the foreseeable future and getting from 3/4" thick down to 1/2" or 7/16" is a lot of wood removal.
Mark
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Hi Mark, To my mind, Pyramids seem well suited to board bows, as a good table saw gets you almost there. However steaming recurves into boards will be a bit more problematic than steaming staves, but Marc has a technique I like.
http://www.primitivearcher.com/smf/index.php?topic=62668.15
The crown on staves makes getting a pyramid profile hard to rough out, but on the other hand I have seen tips "recurved" by both gluing on an exaggerated tip overlays, and by v splicing
Have you seen? http://www.primitivearcher.com/smf/index.php/topic,35312.0.html
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One more question comes to mind - how do you get down to an even thickness for the full limb length on a pyramid bow? I am stuck with board bows for the foreseeable future and getting from 3/4" thick down to 1/2" or 7/16" is a lot of wood removal.
Mark
It takes minutes with a band saw or a planer. I often use a block plane, but finish with a good goose-neck scraper. Long even strokes. Nice exercise with the last. Do try to wear a mask, please.
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Hi Mark, To my mind, Pyramids seem well suited to board bows, as a good table saw gets you almost there.
Yeah, I'm not complaining about the boards as the price isn't bad and I have access to maple, red oak and hickory locally. They do fit into the pyramid bow design very well and I do have a table saw.
Have you seen? http://www.primitivearcher.com/smf/index.php/topic,35312.0.html
I hadn't read that before. Hadn't thought about using the table saw to remove thickness like that but it would work better for that than my bandsaw, which doesn't like to cut really straight lines in thicker material. That may be the winner for the next bow.
Mark
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I hadn't read that before. Hadn't thought about using the table saw to remove thickness like that but it would work better for that than my bandsaw, which doesn't like to cut really straight lines in thicker material. That may be the winner for the next bow.
Mark
When I use a bandsaw to reduce the thickness of the bow from the belly, I first cut out the wood at a 45 degree angle from the side, from both side of the belly. Then I cut the belly almost, but not quite, to the intended thickness. After that I use a block plane, Farrier's rasp, or scraper. Good luck.
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I have had good luck cutting square sections off the edge of boards and flipping them 90 and regluing. I made some stock for backings this way that became "quartersawn" out of of a flatsawn board. Do you have hard maple available? in the US, maple species are graded hard and soft. Of course the hard is more difficult to find, but is commonly the desirable sugar maple often found in Canada. I suspect that it might get mixed up some, and a dense maple board is likely to produce a good performer even if it came from the soft pile.
Hadn't thought about using the table saw to remove thickness like that
I suppose if one derived a thickness that was reasonable, one could always tiller for weight by removing wood from the sides if the bow was too heavy or shortening (piking) the limbs to raise weight if the bow was coming in light.
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Do you have hard maple available? in the US, maple species are graded hard and soft. Of course the hard is more difficult to find, but is commonly the desirable sugar maple often found in Canada.
The mollegabet bow I am finishing up is from a maple board I got at the semi-local Home Despot. The big box stores aren't so sophisticated as to know what species of maple it is, but I will say this stuff is stupid hard to work. If it is the soft maple I don't ever want to try using the hard maple.
I suppose if one derived a thickness that was reasonable, one could always tiller for weight by removing wood from the sides if the bow was too heavy or shortening (piking) the limbs to raise weight if the bow was coming in light.
I don't ever expect to get so lucky as to hit the thickness that close on the first try, but I want to get reasonably close (on the thick side) with power tools and then just work it from there with hand tools.
Mark