Osage Sapling Sapwood - tillering check.

[Jim Davis]

I think you did push the stave to its limit. You did well to get to 27".  2" of set is not a failure. You may gain some draw weight with the toasting. In that case, you will need to approach the 27" draw very carefully, because the wood will be more stressed than it was before the heat treatment.

Jim

[bradsmith2010]

maybe consider drawing less than 27 if you heat treat,,
you may be able to get good cast at a lower draw without taking on more set
why compromise the set and cast to get to 27, when performance may not increase with the longer draw,,
maybe even have less cast per # if it takes on too much set or breaks
if you find a sweet spot as you re tiller,, let the bow dictate the draw,,,

[mwosborn]

I went ahead and "carefully" heat treated this bow.  It took quite a bit of set and was "sluggish" and I wanted to see how the rawhide would hold up to heating.  It came out of the heating looking pretty good - rawhide remained in good shape and the limbs back to straight.  I let is sit a few days and then strung it back up - tiller did not seem to change much, but it did gain some weight.  I gradually got it pulling to 25" and was removing some weight.  I decided to drop down to maybe 45# or so to take a little stress off the limbs in hopes of less set.  At this point the limbs were holding well with not much visible set.

It was looking good at 25" and pulling right at 45#.  The tips were still pretty rough and bulky so I decided to thin and shape them a little bit at this point.  After doing this, I strung it back up and gave a little pull to exercise the limbs a bit and I heard the dreaded "tick".  The back gave away about 8" from the top tip.  It did not break completely, it cracked though the first couple of rings of sapwood that had been damaged by the bugs.

I decided to "dissect" the bow and learn what I could.  I scraped the rawhide off and scraped down through the surface sapwood a bit.  Under the surface that I added originally added sawdust and titebond was not pretty!  See first picture.

I then went ahead and cut the limb in half at midlimb to see what the inside looked like (there was no sign of surface damage at the point I cut).  Lots of internal damage that could not be seen until it was cut in cross-section.  See second picture.

Lessons learned...

Osage (even "wormy") is some tough wood.
If there is insect damage on the surface, it is probably worse inside.
Select quality wood with no insect damage.
Heating osage sapwood will increase weight.
You can heat treat the belly without damaging the rawhide on the back.

I do have another sapwood sapling stave that is insect free - it is only 53" but I think I will try a bending handle bow out of it some time in the future.

Thanks for the help.

[burchett.donald]

 Dang it! The worms had that one from the start...I hate it man, A+ on effort and trying though...That's how bowyers are made...
                                                                             Don

[PatM]

No way that honeycomb was going to have any integrity.

[mwosborn]

You are correct Pat - glad it broke when it did.  It didn't "explode", it was actually only a small crack through the first ring or two of damaged sapwood.  Just goes to show how tuff wood can be. 

On second thought, it could have broke earlier in the process and saved me some time!

[Chadwick]

Oval was the correct term, and SO was ellipse. Ellipses are a subset of ovals, just like osage is a subset of 'tree'. All ellipses are ovals, but not all ovals are ellipses.
Brave effort on this stave -- Hard to know in advance when you're doomed.