Sinew delaminating yew sapwood

[Mesophilic]

I have a yew bow I've been working on from a pretty knotted stave, this is mostly an experiment.  I put one course of sinew down and at the time induced some reflex.  Turning out well and then I noticed several spots along both limbs where the sapwood is being pulled apart.

Is she a gonner?  Or would some sinew wraps hold everything together?

[Newindian]

That’s odd, some more pictures would help, I doubt it’s something that superglue and a wrap wouldn’t fix

[Weylin]

Huh, I've heard of that but never seen it happen. The conventional wisdom is to remove the sapwood and put the sinew on the heartwood for yew. Gordon Ferlitsch made a sinew backed yew bow a while back and he left the sapwood on with no ill effect. Curious to see what others say.

[Mesophilic]

We'll see if imgur will work.  Since photoobucket crapped out I haven't figured out the image sharing game.

The first pic I posted above shows the most detail, not sure if you can even see it that well in these following pics.

https://i.imgur.com/uCpC7lf.jpg
https://i.imgur.com/Ur36v0H.jpg
https://i.imgur.com/aYTSSyV.jpg

[Eric Krewson]

I was making a R/D sinew backed osage recurve, I used a stave that had some side checking that I was able to get out of when I laid out my bow. I thought the bow would be OK but I had problems with side checked wood in the past.

As the sinew cured it started delaminating the osage, both limbs. I tried to fill the cracks with urac and lamp everything back together but it was a no go, the bow was toast.

[PatM]

My Elm  sinew backed bow for the trade separated right on the neutral plane in a similar way.  The stave was unusually dense but also unusually non interlocked grain for Elm.

[wizardgoat]

I’ve seen this happen on wider juniper bows. If it were me I’d put some thin super glue in there and carry on. Is that all yew sapwood? Will be interesting to see how it holds up.

[DC]

How wide is the bow where it delaminated?  If Goat has seen this on wider juniper bows maybe that's the key. Is there is a limit as to how much shrinkage wood will take sideways?

[Pat B]

Years ago someone told me not to use ERC sapwood/heartwood for a sinew backed bow for this reason, I didn't but I've never seen it happen.
Could there have been unseen wind checks?

[High-Desert]

I had this occur on a wide Juniper, and a yew heartwood bow, but only once I moved to the desert, I just assumed it was drying too fast. Never had this happen when I lived where it was higher humidity on the west side of Oregon. The Juniper had cracks the full length of the limb down both sides of each limb, that where over a mm wide. I filled with CA glue to get deep in the cracks, then put TBIII in the cracks and let dry, then did that until the cracks where filled. I put rawhide on the back and wrapped over the side to cover the cracked area. Been shooting the bow for the last year. Maybe I got lucky and it just hasn't blown yet, but as of now, its a great shooter.

Eric

[Mesophilic]

It's 1.25 inches wide where thr first crack starts.

Overall stats are 1.5 inch at the fades tapering to 3/4 at the nocks.  65 inches nock to nock and pulling about 55 to 60 pounds at 28 inches.  End goal is 50 to 55 pounds.

It has a thin amount of heartwood on the belly.  It was mostly tillered before the sinew and added reflex, about 50 pounds.  Blew my mind how much draw weight this added and I've had to remove much more heartwood than I figured it would.