crack--help!

[jeffp51]

This was supposed to be a trade bow.  Pyramid layout with stiff handle.  There was a recurve on one side that I heat matched on the second.  I did a light heat treating that did not significantly change the color.  The wood is siberian elm with heartwood on the belly and sapwood on the back--which was just below the bark--no rings chased.  the stave was 66" nock to nock. and 2" wide at the fades. It cracked during an attempt to bring to low brace. I had heard a small tick beforehand, but since I couldn't find any damage, I kept going. one the side picture I put a pencil mark (left side) where the crack is.  There was no visible damage or knot at that point prior to the crack.  Can anyone tell me what may have happened?

[turtle]

I have had the same experience with elm before. Its just a bad stave. I think its caused by a fungus.

[Badger]

  My first guess without seeing anything is that you may have a hinge at that spot and possibly the bow was too strong when you tried to brace it. I like to know how heavy a bow is when I am bracing it. Most of the time I can tell by feel but if not you can simply measure it on the long string. Doesn't change very much when the bow is braced.

[sleek]

I dont see any excessive set there so id be hard pressed to say there was a hinge. Its possible the ring is trying to delaminate. I have had an elm do that. Other woods also but since its elm we are talking about... How long after heat did you brace? Did you make any new guy mistakes like puttin a knee into the limb instead of the handle to brace it?

The profile looks good and those dimensions should work well. Was the stave stored properly and not allowed to degrade before being built? What does the end grain look like?

[jeffp51]

if anything, that area was a little stiffer.  I was not pressing on the limb, and it had been more than a week since the heat treating.  the sapwood rings are a little thin, and the heartwood plenty thick. when I scrape, though, I get more powdery dust, instead of shavings as I did with the other woods I have worked with.  The stave has been inside for most of the time since I cut it--and off the ground and under cover for the whole time.

[E. Jensen]

Dang thats tough luck!  I can't tell why it did that.  I wonder if that didn't have my name on it, with my luck


 

[sleek]

Powdery dust you say? Thats odd. Sounds like you are into the early wood. Scrape below the crack, chase a ring really but elm doesnt require perfection. You may be surprised to find you still have a bow. Try to decrown the bow while you scrape. That will relieve back tension. If its only at a low brace you could still have a shooter when you are done.

[jeffp51]

Nope.  The crack goes through several rings. Nearly to the heartwood.  This bow is finished.

[E. Jensen]

That's odd.  My trade bow is also siberian elm.

[PatM]

Siberian elm is said to be brittle and very weak.

[George Tsoukalas]

Looks like the crack is knot related.

Knots need to be left a bit wider than the rest of the limb. Let the knot swirl around the width portion of the limb.

Imagine what a brook (creek...for you none New Englanders)  does as it goes around a rock.

Similarly, let the knot swirl.

Moreover, knots are weak spots. Therefore, the knotted portion needs to appear slightly stiff and not bend as much as the rest of the limb.

Working and tillering a bow with a knot takes practice and  maybe a bit of trial and error.

Also, resist the temptation to aim for that picture perfect tiller. Like I said tiller the knot slightly stiff.

Jawge

[bushboy]

That sucks man!been working with elm(white/american)alot lately and never had a tension failure yet.maybe the tree was dying when cut,fungus damage?doesn't make sense for it to fail early on in the build.where the rings paper thin?

[Josh B]

I agree with turtle.  I've also had elm do that and the scraper produced powder.  There was no discolor or any other indicators that the wood was compromised other than the wood didn't "feel" right while working it.  I also think it's fungus that caused it.  Sorry man.  That's a bummer.  Josh

[Badger]

  The straight across break and the powdery scrapings really do point to fungus.

[PEARL DRUMS]

I to agree with turtle and Josh. Hickory will even do that at times. That's a clean shear in tension, and it sucks. Sorry.