Primitive Archer
Main Discussion Area => Bows => Topic started by: MulchMaker on January 20, 2017, 03:04:49 pm
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I love this stuff, black locust is easy to get the bark off in winter time, it grows everywhere and strait! It roughs out easier as well. I've seen beautiful heartwood bows on this site and I've seen beautiful heartwood/sapwood bows. You can use it if it's dead or alive. Cool wood. So black locust fans what are your tips and tricks? If doing a mostly sapwood with little heartwood sapling style bow what should I look out for? When doing full on ring chasing big stave style bow anything I should do different than say hickory? Can you do a green reduction to bow blank then fast dry? I just reduced a sapling down and took the bark off limbs are 1 1/4 inches wide half an inch thick and 6 foot 5 inches in length. I have 4 nice 8 foot staves drying bark on as I don't know if I should take it off. Thanks for taking the time to read/respond
Zach
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I will be interested to hear some replies, and hopefully you don't mind me adding a few more questions about this wood.
I have a log about 4 or 5 inches round by 6ft long drying at the moment, I cut it early last spring(feb 2016). I cant wait to start working on it when it dries. From what I read a while back, it is best to slow dry this wood... But I'm hoping someone with experience with quick dry chimes in.
Do you find the staves with bark rust work ok? I have a lot of black locust around here, but they are all covered in like a rusty color on the bark.
Do smaller 1 1/2" to 2" trees work ok for bows? I imagine these have a very rounded back?
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I've made a dozen or so locust bows. It seemed to work bestid to make them at least 2" wide at the fades in order to get a bow in the mid #40s. That's if you want to avoid as much set as possible. I always made pyramid bows, which gets you close to good tiller by just keeping the limb a little over 1/2 thick for the full length and only tapering the sides--from the fades to the tips.
I agree that locust has a very nice growth pattern and is often straight and without twist. Much better about that than Osage.
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I'm a huge fan of BL. Once I get my bows to floor tiller I heat heat heat those bellies on a caul and put 2" of reflex in them. Then start tillering. I o my use the heart wood. Don't like the sap.
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I love the stuff and have done all kinds of things to it and made all kinds of bows from it. It can take a high crown on the back. I have poor success with sapwood, but a sapwood back is fine. It can be tricky to chase a ring because it can wiggle and roller-coaster and have knots like osage, and while the ring texture is distinct, the colors often change, run out, or are all the same. Chasing down sapwood rings and leaving one sapwood ring or whatever, it is hard to see the early ring.
Locust warps less than a lot of other woods while drying, but can check if you try to dry it too fast.. I like staves from bigger trees with locust, like 6-8" in diameter, while I prefer white woods like elm to come from 3-5" saplings. I like thick growth rings and thin early rings, and dense wood. You can back it with bamboo or hickory. It takes heat treating well.
NOW, the endless jam you hear about BL is that it is weak in compression. I'm in the camp that says "no" to that, but with some caveat. Black locust (0.66-0.77 SG) is lighter than osage (0.76-0.86 SG). BUT it is slightly STIFFER (M.E. is 2,050,000 ft lbs/square inch for locust, 1,689,000 ft lbs/square inch for osage) and has higher crushing strength (10,200 ft lbs/square inch vs 9,380 for osage) BUT, BUT, BUT it's janka hardness is much lower (1700 vs 2760 to osage) and it is a tad less elastic.
All that adds up to a wood that feels extremely stiff and strong, but is STIFFER than it is ELASTIC. I can't call that "weak", but a locust bow will be thinner back to front than you expect and still be very stiff. If you bend it too much too early this stiffness WILL fret the belly. It's definitely less forgiving of being overstrained, and "overstrained" feels like a design should be able to get away with. It's not weak, but it is so stiff it'll feel like it should be treated like osage, and you can't do that. You must count on it being thinner when finished, and wider.
Osage doesn't grow where I live, and I've only used it a few times. Locust in my favorite locally available bow wood.
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...NOW, the endless jam you hear about BL is that it is weak in compression. I'm in the camp that says "no" to that, but with some caveat. Black locust (0.66-0.77 SG) is lighter than osage (0.76-0.86 SG). BUT it is slightly STIFFER (M.E. is 2,050,000 ft lbs/square inch for locust, 1,689,000 ft lbs/square inch for osage) and has higher crushing strength (10,200 ft lbs/square inch vs 9,380 for osage) BUT, BUT, BUT it's janka hardness is much lower (1700 vs 2760 to osage) and it is a tad less elastic.
All that adds up to a wood that feels extremely stiff and strong, but is STIFFER than it is ELASTIC. I can't call that "weak", but a locust bow will be thinner back to front than you expect and still be very stiff. If you bend it too much too early this stiffness WILL fret the belly. It's definitely less forgiving of being overstrained, and "overstrained" feels like a design should be able to get away with. It's not weak, but it is so stiff it'll feel like it should be treated like osage, and you can't do that. You must count on it being thinner when finished, and wider.
Osage doesn't grow where I live, and I've only used it a few times. Locust in my favorite locally available bow wood.
Springbuck, I agree with your conclusions 100%. I do want to point out, however, that every set of mechanical properties numbers for Osage available ANYWHERE is only the set for green samples. the Forest Products Laboratories did the only extensive tests on American woods and they did not record the numbers for oven-dry Osage, though they did for every other wood they tested. Numbers found anywhere else are merely copied from the FPL tests. Nobody has done any new tests, although some try to make it look as though THEY are the authority.
The result is, that it is impossible to make a realistic comparison between the numbers for Osage and those for any other wood. We are left to our experience. :(
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Have used it quite a bit. My favorite design is a 64"-66" R/D. I have not seen it neccesary to go more than 1 5/8" wide for locust. I have made some short bendy pyramids and have gone up to 2" wide. Heat bends well and likes to be heat treated. Good wood.
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It's many a bow makers' favorite type wood or at least right up there.Including me.Saplings make great flat bellied D bows.Flat bows make excellent bows too.A little wider than osage at the same lengths.No tricks just the basic rules of careful tillering.It's a very quick wood on it's own I'd say without any stressful design put on it.Takes heat treatment well but turns dark the quickest of any wood I've heat treated.
One of my favorite bows I've got is a BL bow puling 54#'s @ 28".63"TTT mild R/D stiff handled lever bow.Only weighed 13.00 ounces after heat treatment.A quick bow even without much set back of the limb tips. Not your usual handle pop off[fix & pics added][finish & pics added]
Many from the Pa love this wood.Just me but your staves I would chase a ring and shellac the back and ends.It'll dry faster for ya too.
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I love black locust. Like everyone has said, it takes heat treat very well. After heat treat it usually set my tiller back by 5-6" at the same weight. I make most of mine 1.5" wide to about 55# unless I make the limbs short and high stress, then I bump up to 1.75". I've never done a fully sapwood backed bow, but I love going to to transition ring. Sometimes you'll get mostly heart wood with streaks of lighter sapwood.. Might be worth trying a flat bellied ELB style with your narrow stave.
Kyle
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I learned on BL. It is a very good bow wood and one of my favorites.
As a side note it also heat treats well.
Jawge
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Thanks for your replies, should I urathane the back of the mostly sapwood bow or since it's reduced enough just let it dry?
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A light coat won't hurt a thing.
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A light coat won't hurt a thing.
Always better safe than sorry. Slower drying prevents SOME warping, as well as checking.
Asharrrow, I did not know that, or had forgotten it. Thanks. That would change the hardness and crush strengths a LOT, along with everything else. I'm shocked that the US government data base folks couldn't get their hands on a dry sample, when they have so many woods from all over the world.
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Thanks guys, hopefully soon I'lll have some beautiful bows to show you, love this locust so far, sure easy to split. Thanks again and good luck on all your endeavors.
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Ah ha I found it!!! Jimmy made it and now I want one too! I thought the thread was on another site but it is right here http://www.primitivearcher.com/smf/index.php?topic=35601.0 this was my whole idea for the sapling bow
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Asharrrow, I did not know that, or had forgotten it. Thanks. That would change the hardness and crush strengths a LOT, along with everything else. I'm shocked that the US government data base folks couldn't get their hands on a dry sample, when they have so many woods from all over the world.
Oh. I'm sure they had dry samples, did the tests, then LOST the results before they could be entered in the database. It's ironic that the wood we would most want to see numbers for is the one they don't have. There are some hacks there now who are less interested in the science of wood than in making a pretty website. One of them told me some years ago that the numbers for dry Osage wouldn't be much different from those for green Osage! A dolt, I think.
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"One of them told me some years ago that the numbers for dry Osage wouldn't be much different from those for green Osage!"
Yeah, I ain't buyin' it either.....
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So if we don't have good numbers for Osage do we have good numbers for yew or are we comparing because of similar kind of tree?
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I was comparing them because they are both commonly used, fairly heavy, and are often treated much the same, being on the upper end for wood strengths and density, at least for native North American hardwoods.
The website has specs on a ton of woods, and I always assumed their testing was somewhat standardized. They measure what it takes to bend a bunch of samples, what it takes to break a bunch of samples, physical weight per cubic foot, side hardness, longitudinal crushing resistance, specific gravity, etc... they even rate woods for different applications if you search for spmething like "bows" or "eating utensils" or "tool handles", but they don't cover everything, and some of their conclusions, esp about bow woods are suspect to me, as if they were done from behind a desk, you know?
But, if the testing isn't careful and standardized, then it's all partially out the window at least.
http://www.wood-database.com/ they do have specs on yew.
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It's my understanding that the Wood Data Base ( http://www.wood-database.com/ ) has only copied the data from the Forest Products Laboratories https://www.fpl.fs.fed.us/research/centers/woodanatomy/index.php (https://www.fpl.fs.fed.us/research/centers/woodanatomy/index.php) which did it's testing beginning in the 1930s. I like to see credit given to the agency that did the work.
FPL did test many samples of each variety of wood with a high degree of scientific diligence. WDB is just capitalizing on FPL's work.
Bookmark https://www.fpl.fs.fed.us/research/centers/woodanatomy/index.php (https://www.fpl.fs.fed.us/research/centers/woodanatomy/index.php)
Jim Davis
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This is a lot of info to process. Lol, newbie experience is probably the reason. I guess im trying to wrap my head around the uses for these numbers. So a heavy wood like black locust or Osage is more Versatel than say a lighter wood like chokecherry. Is that what the numbers are for? I won't use the term better because I'm guessing that has a lot of different variables on why one chose the particular wood in the first place. Although I am still new every time some one asks "what is the best bow wood in my area" the smart Alec in me always wants to reply "the one that is most abundant that you can identify that will make a bow" for me that is 1 black locust 2 buckthorn 3 chokecherry 4 hickory. I'm glad I got one at least with a heavy numbers. I'll have to look up the other woods I have close by, I'm guessing the other numbers have a lot to do with design as well.
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Jim, that's the site I used to use, and they did have more extensive write-ups. Good catch.
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... Although I am still new every time some one asks "what is the best bow wood in my area" the smart Alec in me always wants to reply "the one that is most abundant that you can identify that will make a bow" for me that is 1 black locust 2 buckthorn 3 chokecherry 4 hickory. I'm glad I got one at least with a heavy numbers. I'll have to look up the other woods I have close by, I'm guessing the other numbers have a lot to do with design as well.
MM, your last sentence tells the whole story as related to the mechanical properties of wood. The numbers tell us how to design the bow. Stiffer wood can be thinner and or narrower. Woods that have a high WML (work to maximum load) number can be thicker. Wood that is denser can also be thinner and or narrower.
The properties work together so that, for instance, a wood that has high WML but is not as stiff will have to be wider than a bow that has a lower WML but higher modulus of elasticity.
We are better off learning what designs have worked with a given wood and follow that example. After making a few bows, then the numbers can start to be useful in planning a different design or a modification.
I think only a mechanical engineer would start out with the numbers and design a bow. But don't turn up you nose at the engineers. Paul Kolpsteg was one and contributed mightily to the sport as well as being a bowhunter.
From my time poring over the numbers, of American woods, I would rate them from best, Osage, Yew, cherry bark oak, hickory (pig nut, mockernut, and shagbark in that order), black locust, persimmon and downhill from there.
Jim Davis
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"I think only a mechanical engineer would start out with the numbers and design a bow."
I started doing this, poring over numbers, while at work on the night shift, while the ER was quiet, etc. Then I would see some numbers I liked and go get a piece. Then I'd say, this stuff is stiff and dense, but elastic and I'll back it with bamboo. So, I'd do it. Then I'd work it and say to myself, this stuff acts kinda like, "X" other wood, so maybe next time I'll.......
So, I found a few nice tropicals that were pretty and worked with a backing, etc........ Otherwise, I agree with your list pretty much completely, and it's nice to find out a lot of woods (like white woods as a whole) act pretty much the same, and need only minor changes that can be made during construction and tiller.
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At this stage of the learning curve I think I'll play it safe and keep it simple. I think since I have a lot of locust I'll stick with that and make a few bows before I start working others. The beauty about this wonderful hobby is that I can collect wood I wanna try later any time. The first goal is to be successful the second is to improve my work. I figure I've got some at least 2-3 bows to break if not 30 before I get a shooter. I may able to lessen the breaking if I don't drastically change my material every time. Wood has differences between trees, changing the type of tree will make the difference to different. Thanks for the help, and for helping me select a path.