Primitive Archer
Main Discussion Area => Bows => Topic started by: Rob W. on February 28, 2016, 11:39:20 am
-
I don't have any experience building bows out of smaller trees. I'm just wondering if I'm going to have problems with this smaller piece and what should kind of layout I should shoot for? I have plenty of length. Thanks guys!
(http://i1225.photobucket.com/albums/ee391/rjwalton8/20160228_112023.jpg) (http://s1225.photobucket.com/user/rjwalton8/media/20160228_112023.jpg.html)
-
If that is osage you shouldn't have any problems with the crown. Do be sure you have a pristine back and a flat belly. I've built a few osage "pole" bows, about 2" diameter, that pulled between 40# and 55# and all shot very well. I've even made them with sapwood on the back.
-
Do be sure you have a pristine back and a flat belly.
I would like to know why you advocate a flat belly here. My advice would actually be to round the belly a bit too, to make sure not all the forces are concentrated on the back. A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back. That may be safer with this extreme crown. Don't round the belly as much as the back, but just a little bit.
-
Which wood?
-
DS, I've only used a flat belly on this type of bow but will try a rounded belly next time.
-
I have done both round and flat,, both shot fine,, and have heard advocates in favor of both for one reason of the other,,, I still don't have any idea which one would be better or why,, :)
-
Yeah it's osage. I would like to build something around 64" but I can go longer if you guys think I should.
-
If you dont like the high crown just decrown it, simple as that.
If you leave make sure the top of the crown has no irregularities, like minute pins.
Joachim
-
A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back.
I would think the neutral plane would shift toward the belly.
Anyhow as someone said, "Compression failure results in set, but bows with set still shoot. Tension failure makes for broken bows." It would be wiser to start with a rounded belly and flatten it if warranted, as we progress.
-
I like to leave sapling bows a few inches longer for safety's sake because tension is concentrated right down the middle of the bow. Jawge
-
Your draw length and weight desired?
-
I would like to know why you advocate a flat belly here. My advice would actually be to round the belly a bit too, to make sure not all the forces are concentrated on the back. A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back. That may be safer with this extreme crown. Don't round the belly as much as the back, but just a little bit.
probley because some folks cant tiller is what im thinking. i do it all the time. never had a problem yet.
-
Riverrat, I'm sorry but I don't get it. What does tillering have to do with a round or flat belly design?
-
A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back.
I would think the neutral plane would shift toward the belly.
Anyhow as someone said, "Compression failure results in set, but bows with set still shoot. Tension failure makes for broken bows." It would be wiser to start with a rounded belly and flatten it if warranted, as we progress.
Indeed, the neutral plane of a crowned or trapped bow moves towards the widest surface. Crowned bows make for safer bellies but weaker backs. Since nearly all woods are stronger in tension than compression (at least above 6% MC), a crowned bow is less prone to set. The only wood I know of that isn't is Erica arborea, a mediterranean shrub.
Moisture control is key to keeping a crowned back in one piece.
Rather than having two crowned surfaces (back and belly), I'd decrown the back a bit and keep a flat belly.
-
it shifts the neutral plain. as well as reduces weight in the lims. if you take it off, its off.
-
I usually leave them flat also, they make a snappy little bow. :)
Pappy
-
I'm always searching for stave like this, the best candidate for a HLD.
Don't know how experienced you are, but a secure way is leave it a bit longer than usual and make her a dead flat belly. I personally would never decrown a stave, but that's just me ...
-
I am enjoying the back-and-forth on this subject. Courteous, respectful, offering explanations instead of excuses or insults. And it looks like we'd run out of cats before we ran out of ways to skin 'em!
Whatever route you choose on this stick, keep posting pics and your observations, win/lose/draw!
-
Who said "Cats" ? Whaaa? I was havin' a nap ::)
Del
-
I cannot understand where a slight crowning of the belly would change the neutral plane of the stave much at all. To keep the same weight bow, the crown on the belly would have to be a little "deeper" than the flat belly it replaces. This would be necessary to account for the reduction in thickness along the edges of the belly. The strain at the center of the belly crown would in fact be a bit higher, but the average stress across the belly as a whole would not change much. Of course if you took a bow with a flat belly and then reduced the edges of the belly to create a crown, the neutral plane would move up, but you would have a different (reduced weight) bow. As Joachim pointed out, the best way to modify the strain profile of the stave, would be to significantly alter the high crown if one does not want to have concentrated stress at the center of the back. If the high crown back can take the extra strain, then it might be advantageous to leave the crown as is for performance, but if you need a bow that won't snap when you least expect it, a flatter crown on the back might be the way to go.
-
osage bows are not likely to snap,, once shot in,, in my experience,, :)
-
This isn't the "which is better " part, but sometimes you just don't have room to choose if the sapling is too narrow someplace or for some flaw reason. We only see one end of the stave.
On a high crowned narrow stave, split in half roughly, rounding the belly narrows the bow. Maybe there's enough meat, it being osage, and the rest of the stave is as wide or better. But if there's a real narrow spot, keeping the belly flat will give you the greatest width out of that stave shape. You'll be rounding the corners some anyway, and that also cuts width. crowning the belly might not be possible someplace. You'll know because you can see the whole thing. This is much more of a concern with white wood saplings, which need more width.
-
This isn't the "which is better " part, but sometimes you just don't have room to choose if the sapling is too narrow someplace or for some flaw reason. This is much more of a concern with white wood saplings, which need more width.
This, to me, is actually the crux of the decision making, if not the theoretical discussion. The first consideration to making a sapling bow is chosing a high tensile strength wood........elm, osage, hickory....
An osage bow, even with sap wood, is not likely to just snap, as some have mentioned, since you can make a pretty narrow design from osage as it is, like an ELB. Likewise, I make elm sapling bows more than anything else, and all with flat bellies, because elm is "ok" in compression and great in tension. I can cut a hard little elm sapling with thick rings 2" across and make a pretty good bow, same for plum, same for white mulberry. I won't cut an ash unless it is 4" at least. Elm can take the tension, needs the width for compression. Ash needs a tiny bit more help on the tension side.
I don't know nearly as much about osage as most of you, but I have seen a few with an almost round, or rounded front and belly, narrow and thick. Just cuz you can get away with it. I think it would take either.
-
but if you need a bow that won't snap when you least expect it,
sorry if I implied attributes to osage or any other particular wood. My post above was generalizing about neutral planes and crowns.
btw, springbuck, I wish I had some elm around here, as it's liked by many for it's tension qualities.
Have you used it with different (more dense woods?) for bellys?
-
If you can find a good clean piece, small trees make great bows. Personally, I would go for something in the 60" range, 1-1/8" wide, bend in the handle and maybe a sinew back. The narrower you make the bow, the less apparent the crown will be.
All my bows have pretty flat bellies nowadays but if I were to make a bow out of that piece, it would have a fairly radiused belly. It wouldn't quite be like you get with the Torges' faceted tillering style but almost.
-
btw, springbuck, I wish I had some elm around here, as it's liked by many for it's tension qualities.
Have you used it with different (more dense woods?) for bellys?
I have, but I didn't have a bandsaw so it was a lot of work. I had heard that the best thing to do is take elm backings off the outside of the trunk, just like selfbows, so USUALLY if that part looks good enough for a backing, it looks good enough for a selfbow. But, I went ahead and did it a couple times when I had tear-out and ruined a bow as I was roughing it out. It works fine, but it's more trouble than hickory or white oak. It looks cool. I think I did a couple goncalo alves, and some locust I had to saw into blanks because of bugs in the outer layers. Been a long time.
I'm surprised elm doesn't grow around there. I find it everywhere, as it blows it's little seeds all over. Vacant lots, river bottoms, fence rows, etc. The city comes and cuts it out of fences along the roads, but they can never kill the stumps it seems, and in 4-5 years I have coppicced little shoots about 3" across all over the place. I could cut a backing on my way home today, if I felt like splicing.
-
Springbuck
Actually I am in Alaska, but I might have some access to some from the lower 48. In fact, tension strong woods are not found here at all.
Were the woods you used as belly wood quite a bit heavier? Those sapling backs seem like a good use for something so proliferous, and often culled, at least better than whacking a nice hickory.
willie
-
Well, hickory doesn't grow wild in Utah, and I do make selfbows more than backed anymore, but why not? If you got it, use it! Getting the thickness right, since it is still the outside of a living tree, is the hard part, and red elms like to grow little tiny branches in rows up the trunk until they are quite big, resulting in little pin knots with small raised bumps. However, various scrubby red elms are the kind you see most, and they aren't great compression woods, but are stringy, scruffy and hard to split cleanly, so, yeah, backings......
I would say, albeit from limited experience, that a good elm backing sawn from the outside of a tree is probably just as good as a sawn hickory backing. Plus or Minus. I mentioned I used locust and a tropical hardwood.
BTW, if you are hard up for backings, I also remember on this site, or Paleoplanet, I don't remember which, where a guy chased rings on both sides of an shovel handle, and sawed it down the middle to make a backing with a chased ring. Kinda cool.
-
inventive for sure, but you gotta go with what you got....
thanks for the tips, springbuck
-
This another case of people overthinking bow making.
How many of you guys concerned about the "neutral plane" have actually made a bow out of a similar osage sprout? Opinions don't count, only actual experience. List all your neutral plane failures from the different belly configurations that you have used. Inquiring minds want to know.......
I have only made one high crowned sprout stave bow that I remember, 64", slightly rounded belly. It shot OK but I didn't like the "look", all back and no belly. I have several more similar staves under the house that I will try sometime, perfect early to late ring ratio, 3-4" diameter if I remember correctly.
-
This another case of people overthinking bow making.
How many of you guys concerned about the "neutral plane" have actually made a bow out of a similar osage sprout? Opinions don't count, only actual experience. List all your neutral plane failures from the different belly configurations that you have used. Inquiring minds want to know.......
Since I'm the one that started the 'neutral plane' issue here...
I have never worked with osage. It doesn't grow in my country, so it's very hard to get for me. But I don't see why pondering over theoretical things such as the neutral plane, makes bow making 'overthinking'. I personally think that my remark of the neutral plane, and the benefits of a crowned belly, have sparked a great discussion. Springbuck's remark "The first consideration to making a sapling bow is choosing a high tensile strength wood........elm, osage, hickory" has hit the nail on the head for me. This osage sapling 'gets away' with the flat belly, because osage can take the extreme tensile strength. So, if this sapling was ash or maple, it would have likely failed in tension. In my opinion, a crowned belly would have shifted the neutral plane enough to the back, as to not tear the crowned back itself apart. So, Eric, this "opinion" is for me very valuable, and I don't need personal experiences per se.
-
Since I'm the one that started the 'neutral plane' issue here...
In my opinion, a crowned belly would have shifted the neutral plane enough to the back, as to not tear the crowned back itself apart. So, Eric, this "opinion" is for me very valuable, and I don't need personal experiences per se.
Again, a crowned surface moves the neutral plane towards to widest surface, not the opposite as stated here.
So a crowned back moves the neutral plane closer to the belly, straining the back even more than with a flat non-crowned back.
Joachim
-
RobW.....I've made those sapling bows from hedge too.Just the way they are off the stump.Bend in the handle like Pappy said good snappy bows.Mine have lots and lots of knots on the belly.If thinking about heat to those knots I would'nt do that.As far as reflexing it a lot.Knots are hard enough the way they are.
-
Point well taken DarkSoul. I have to admit I have been on a personal quest to get folk to share more actual experiences and nothing based on opinions.
Its' like; which would you rather have for your next surgery, a Dr who had done the same surgery a dozen times or Dr who had never done the surgery but has strong opinions on how it should be done.
For a newbie who doesn't know a lot about bow making, all this discussion about "neural plane" just muddies the waters for them and makes something simple seem pretty lofty and beyond the scope of their ability. I want everyone to make a bow who is so inclined, make a bow, tiller it correctly and shoot it, don't worry about the mechanics of the process.
As for osage, I live in osage country and know the wood very well, I have been making bows out of it for 20 years.
I have a little osage put back for future use.
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/stavecollection1.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/stavecollection1.jpg.html)
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/stavecollection2.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/stavecollection2.jpg.html)
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/billetcollection.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/billetcollection.jpg.html)
Like I said I know the wood well, neutral plane is not a topic of contention when dealing with osage.
-
Honestly, I put some time into learning about neutral plane, etc... early on, but I don't think about it much in those terms when making bows. Somehow, I settled into making mostly bows from 5" dia. or smaller trees about 5 years ago, and all I ever think is "what can I get away with here...?"
And the woods I work with the most as saplings: elm, white mulberry, canyon maple, yellow locust, plum, and occasionally hickory, stuff like that, just hasn't had any issues breaking on the back. I tiller as well as I can, and most of them get heat-treated, too.