Primitive Archer
Main Discussion Area => Bows => Topic started by: Academonicon on February 13, 2016, 10:44:00 pm
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Hey bowyers. I just bought a black locust board on a whim, and I'd like to turn it into something shootable. It's pretty short, about 50" of usable wood, but the grain's nice and straight with no apparent flaws or knots/pins. This is my first time working with locust, so any advice on design or other build-parameters would be welcome!
Thanks!
-Nick
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never tried a board for a locust bow. staves are nice because on the belly you can see the rings the way they fade as you tiller. and with b. locust tiller is everything.thats kind of short for anything with a handle and even a D bow best draw your gonna get is 25 inches without backing it.i bet you could make a sweet short D bow out of it. if you can get the tiller.Tony
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Take your board and rip it into 2" wide x 50" boards. Now finger splice them together and you can make a few bows up to 96" long. Locust is so-so in compression. Try backing it with maple. I'd bet that's a nice combo.
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Locust is so-so in compression. Try backing it with maple. I'd bet that's a nice combo.
I don't get why so many folks think BL isn't good in compression. Tension and compression tests indicate it's well above average in both. Granted, it shows when a bow is overstrained or badly tillered by fretting but that doesn't make it worse in compression than woods that don't show this so obviously. Heat-treated BL can sometimes overpower the back because it increases its compression strength even more (didn't Marc St Louis write this in TBB4 on heat-treatment?).
Anyway, I would also make two billets out of that board and splice them to a 65" or so bow.
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i agree, second only to osage and thats a close, very close second in my books. ive made shorter bows of black locust with crowned backs and rounded bellies {i call it lensticular tillering} that shoot fast even with 500 grain arrows.its all about tillering when it comes to black locust. if you get the tiller right you can do whatever you want as for style of bow. if you dont tiller good, well you get checks, frets, and breaks.its easy to make a bow from. just make it bend right :) Tony
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joachimM, I agree, and I think it's weaknesses get over stated sometimes. But, I think there is SOME truth to the conventional thinking. To me, it's NOT that BL doesn't have good compression STRENGTH, because it does. It's more like, for how stiff it is, and how dense, BL is slightly less compression ELASTIC than it feels like it SHOULD be. I hope that makes sense. It's less about how good it is, and more about overestimating it, just barely.
I don't have a lot of experience with osage, but some of the BL I have worked actually seems stiffer than the osage I have worked, but less tolerant of bending, and it will fret where some other woods just take a little set. My record of success with it is higher than other woods, too; I have finished nearly every BL bow I started, and only mulberry treats me as well.
From experience, all of this goes away completely, as you say, if you just make that limb a tiny bit thinner back to front. The guide in the TBB seems spot on to me here: making BL bows 1/8" wider than osage. I've made some (to me) fantastic 66-70" selfbows with BL that were 1-5/8"-1-3/4" and barely on the fat side of 3/8" at hunting weights. The fastest shooting bow I have ever made was a 64" bamboo-backed BL deflex-recurve, MAYBE 1-5/8" WIDE, with big recurves and rattan string bridges, at 52 lbs. That BL slat was some QUALITY wood, quarter sawn, beautiful and dense, a but only 1/4" thick when I started.
Its just great stuff.
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Locust is so-so in compression. Try backing it with maple. I'd bet that's a nice combo.
Granted, it shows when a bow is overstrained or badly tillered by fretting but that doesn't make it worse in compression than woods that don't show this so obviously.
How does that make any sense?
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I don't have a lot of experience with osage, but some of the BL I have worked actually seems stiffer than the osage I have worked, but less tolerant of bending, and it will fret where some other woods just take a little set.
Same question for you Mr Buck?
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I've worked a lot more locusts than anything,g else and it is my experience that it is indeed compression strong but overwhelmingly powerful in compression and also very stiff, most of it being stiffer than any Osage I've touched. It frets because any flaw in its bend takes on a whale of pressure from the unrelenting back. I've made every design I care to with this stuff and as long as my tiller is on point it gives me no trouble. I think a black locust back would go perfectly with some ipe if you could just get a clan chased ring, that'd be an experience and a half.
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That's just it Marc. If the belly cant take the backs strain without perfection or manipulation, then it isn't great in compression. Its so-so. I like locust, don't get me wrong here.
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Pretty straight forward. Locust performs right where it should, but get's overestimated. When designing a locust bow, the design should fit its S.G., rather than designing for it's strength and stiffness. The stiffness can fool you, and fools a lot of people into making the wrong bow. Locust can take less SET than, say, red mulberry, but still show those tiny surface compression fractures. If you compare the two on the basis of compression strength OR elasticity, the bow with with the most set is obviously the loser. Locust would lose to osage, but it isn't WEAK. Rather, osage is exceptional.
BAD or WEAK in compression, it is not. WEAK in compression would be cottonwood or poplar, mahogany, or paduak. It's stronger and more elastic than almost all common bow woods. Far better IMO than even the hardest elm, maple, ash, etc.... Lot's of people confuse compression strength with compressive elasticity. Locust has plenty of both, but not the elasticity osage or massaranduba do. But, it's a good step lighter, too. Osage runs in the 0.80's for SG, and locust runs in the 0.70's.
Several woods much lighter than locust seem to have better compression elasticity, like yew, ERC, other junipers, and lately I've been hearing a lot about plum. Plum is a good example of a LIGHTER wood that very elastic for it's weight.
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Comparing compression strength relative to other woods means taking tension out of the equation, so for instance a locust belly with a maple back will do better than a maple belly, but a maple belly with a locust back would probably have more problems than the locusts belly.
I really want to see this done with locusts and Osage, actually.
All this being said I've made very compression intensive designs with my locusts and it does just fine, a little snappier than Osage it seems but I think that's just the designs I've used for Osage so far, I should get a stave for a Mollie and a 1x50 r/d bow as those have been my two fastest shooters.
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Nobody said it was weak in compression but so so which by most of the statements made above kinda say that exact thing
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But it's not even that, it's a very strong wood in tension and compression but even more so in tension. I have to tiller it just right every time but so far it hasn't failed to pull off any design I've thrown at it and one of my favorites is anything but flat and wide. Its compression falls short of Osage and yew for sure but that leaves it at the third best compression wood In north America.
All this being said it's been my experience that a broken back ring will tear itself apart so definitely back your board.
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Nobody said it was weak in compression but so so which by most of the statements made above kinda say that exact thing
Your just spinning your tires off, Bub.
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Yup
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I'd be afraid of that board being kiln dried myself.
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Thanks for the advice, everybody. Didn't expect to stir up controversy! I'd like to do some kind of laminate backing as some people have suggested, but I've never done that before. Anyone have links to build-alongs or guides to doing a maple backing or something along those lines?
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No controversy. Some people just read what they want to read and not what is typed. Very typical on forums.
Search Google for "Perry reflex". I bet you find a million pictures and instructions.
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Oh, also for a first-time wood backer: Where does one come by wood backing strips (if, like me, you don't have equipment to make them yourself)? I know hickory and bamboo strips can be bought on line, but I don't know about other materials.
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I scored about 25 usable staves of BL off a lady on Craigslist who was downing some trees.
Some staves had 1/4" thick late wood rings and made awesome bows, while some staves
from the same tree felt like mush at floor tiller.
I designed a couple much like I would an Osage bow and I haven't seen a fret yet.
If you can find some clean hickory or maple, you can rip your own backing strips on a table saw
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Oh, also for a first-time wood backer: Where does one come by wood backing strips (if, like me, you don't have equipment to make them yourself)? I know hickory and bamboo strips can be bought on line, but I don't know about other materials.
Try to locate a local woodworker or cabinet shop. they wouldn't have a problem ripping up a few boards of black locust and maple into strips.
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Academicon, rip and splice it of you can, if it is wide enough (at least 3 inches). It's a board so the grain structure is paramount and will determine if a backing is required. Straight grained tip to tip is the ideal.
There's more info on my site.
Black locust is a very good bow wood. I cut my bow making teeth on it back in the late 80's early 90's. The BL that grows in my yard is not weak in compression.
traditionalarchery101.com
Jawge
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Okay, encountered an issue working on this bow: After splicing the billets, I managed to get a propeller twist due to an uneven splice. The splice itself is strong, but now that I've glued (with Titebond III), I obviously can't steam the handle to remove the twist from there. What should I do about this? The twist isn't super severe, but I worry that it'll cause problems down the line.
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Flatten each limb out and shift your handle centerline accordingly.
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Ever heard the saying that anyplace is within walking distance if you have enough time?
I have used a Japanese Pull saw to saw a hickory ax handle into backings. I smoothed it on a board glued with sandpaper.
I saw another guy chase rings on both sides of an ash shovel handle, and do the same.
You can do bamboo by splitting to size, clamping flat, and using a rasp and paper.
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"Granted, it shows when a bow is overstrained or badly tillered by fretting but that doesn't make it worse in compression than woods......"
This makes perfect sense to me. The first step is considering if something OTHER than compression strength is to blame.
About any wood can be made to fret if overstrained. If locust frets when poorly tillered, it may be out of compression being so-so, or it may be that it is simply so stiff that TINY thickness issues are magnified, making some spots much stiffer than others even when the thickness difference is TINY. Likewise, we know a lenticular cross section is technically thicker than it needs to be, and compression forces are concentrated on the belly crown, so of course it will show some marks.
But, I DO trap my locust bows, just like I do ash, elm, hickory, mulberry, maple, dogwood and almost everything else unless it's already crowned on the back, and I prefer flat bellies with locust. One "case in point" to me about it's properties is that I have been VERY successful with backed locust bows, regardless of whether I used hickory, ash, or bamboo. I attribute this to the more rectangular cross section and even, predictable geometry.
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I always looked at it in such that the compression is average where the strength and elasticity are good to exceptional. The compression isn't weak it just isn't as good as the other qualities of the wood.
According to the wood database, BL has a higher compression strength than osage(which was surprising). So it's more than just the one factor. It's how all the properties meld and react together.
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I think the biggest area locusts loses to Osage is its jenka hardness, which is related in part to density. Locust is stiffer per mass but fretty in the belly, more snappy but you can hurt it beating brush out of your way. If your bow is too fragile for a hunt you've done something wrong and locust isn't weak compared with most good bow woods but every mistake in the build is a bigger deal when compared to Osage.