Crown problems?

[Pappy]

I usually leave them flat also, they make a snappy little bow. 
 Pappy

[simson]

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 ...

[JW_Halverson]

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!

[Del the cat]

Who said "Cats" ? Whaaa? I was havin' a nap
Del

[willie]

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.

[bradsmith2010]

osage bows are not likely to snap,, once shot in,, in my experience,,

[PlanB]

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.

[Springbuck]

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.

[willie]

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? 

[John Scifres]

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.

[Springbuck]

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.

[willie]

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

[Springbuck]

  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.

[willie]

inventive for sure, but you gotta go with what you got....

thanks for the tips, springbuck

[Eric Krewson]

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.