will trapeziod help chrystals in black locust?

[bowberry]

this is for all you selfbow folks.i built a black locust selfwood bow. i really love the wood and the bow 52#@28.but. the belly is developing chrystals badly. (on my next bow)would the trapeziod shape ive read about help reduce stress on the belly ( assuming good tillering)?

[mikkekeswick]

If your back is flat (from a big tree) then yes for certain it will help. If however you make your next locust bow from a sapling then the back is already highly 'crowned' and won't need trapping - the crown giving the same effect of a narrower back.

Locust will teach you what you've done wrong on this one. Are the chrysals in one area or one whole limb or both limbs?
So for example if you made a bow, perfectly tillered but it was just a bit too narrow then the belly will develop chrysals everywhere. If you had one limb stronger than the other but still bending perfectly then only the weak limb would get chrysals. If you just had one weak spot then just that area would get them.
Locust is my favourite selfbow wood due to it ability as teacher and it makes super fast bows as it is very stiff per thickness.

[Black Mockingbird]

+1 mike...locust will tell you what you did wrong. Can u tell us more about it so we can narrow things down. Like bow length, limb widths,pics of bow unbraced,braced,n full draw?

[bowberry]

Thanks for your replies. No pictures at this time. This is a sapling bow.(i have enough growing in my yard to build an army, so I would like to figure this out)
Starting as a 2"-2.25" sapling,the finished bow is About 70" long.1" wide at handle,limbs are about 1.5" wide at the fades, pretty much straight for 2/3, then tapered to 3/4" at the nocks.
The top limb is about 1" longer than the bottom.
limb thickness is about 11/16" thick at the fades, tapering to about 3/8" at the nocks.

[bowberry]

All the checks are from the fades out to about mid limb on both top and bottom limb.I know it is not bending enough in the outer third of the limbs.This is only my forth bow, so Im a little nervous of taking off too much.

I thought it was getting close, so I started shooting it. OMG it was beautiful. Then I fell in love. After that I really,really didn't want to wreck it.I decided the tiller was good enough and it was a shooter.
 after a couple weeks of heavy shooting I noticed all the chrystals in the belly.


I started out with a half round back and a flat belly, like the letter  D.  I flattened the sides a tiny bit.Then I blended/radiused the sides into the belly and back. So I ended up with a eliptical cross section.

[mikkekeswick]

Sounds like you've got it - you just need to practise. Tiller is only one of two things - perfect or not good enough! Never say 'that's good enough' because if you bend it too far when there is a weak spot/stiff spot you have already done the damage to the wood cells and it will eventually break down.
With the width taper that you describe the tiller should be elliptical eg. as you move along the limb the bow should bend progressively further, little bend out of the handle, midlimb bending more and the most bend at the mid/outer limb section.

[mikkekeswick]

This is a different bow but this is an elliptical tiller.
Also take your nocks down to 1/2 inch wide. Stick with the same width taper on your next one too.

[bowberry]

Thank you for your help. One more question.Ive read that black locust is prone to chrystaling. If I can learn perfect tiller, is possible to have a black locust bow that doesnt chrystal? Or do they all crystal somewhere?

[mikkekeswick]

Yes most certainly it is possible and definitely achievable.
Just keep trying and never pull it further than needed to see a problem area.

[Pat B]

I cut my bow building teeth on black locust. I probably made a dozen or so bows from it in my early days. I stopped using it because of too much set and chrysals. That was before I knew about well seasoned wood or over stressing wood as you build a bow.
 Now, when I make a black locust bow I build it as if it were whitewood, longer and wider with a flat belly. I also temper the belly and trap the sides if appropriate.
 As said above, locust will teach you to be a bow builder if you let it...or make you quit all together if you aren't really serious about the craft.

[takefive]

I've never tried black locust, but have heard that it is prone to chrysal if your tiller isn't spot on.  A bowyer on Primitive Archer uses it almost exclusively and he really know his stuff.  Here's a pretty cool build along he did:

 http://www.primitivearcher.com/smf/index.php/topic,44858.0.html

[bowberry]

takefive; nice build along, thanks.

Pat B; If you temper the belly,does that reduce crysaling? also my wood was not necessarily "well seasoned"


In the end, I know my tiller was the culprit. My next one will be better. I just wanted to hear some ideas of what else would better my odds. thank you all so much for your help. Scott

[Pat B]

Tempering increases the compression strength. I've used it on the last two locust bows I built and neither fretted. Both staves were well seasoned and my tillering is a lot better then way back then. Well seasoned wood will always make a better bow...and tempering a bow with noticeable moisture in it is asking for checks in the back.
 Design should also be a consideration, design the bow for the draw weight and draw length. Locust was the #1 bow wood for the Cherokee and other Eastern Woodland Natives but many of their bows bent through the handle distributing the stresses even farther.