Lessons Learned Along the Path to The Break of #4

[gables]

I spent the weekend building a fourth bow with my good friend.

The first long bow we made was from a Bingham design and a Bingham Kit with back and belly glass. Second one was of our own design, 62" reflex deflex, (same form for bows 2,3,4) and a Bingham kit with back and belly glass. It is a bit heavy for us but shoots great. The third bow was the first bow where we ground our own lams and it came in at 22# when we were shooting for 50#. We built that bow similar to Byron Ferguson's description in Become the Arrow of a bow where he builds in a center strip of .030 uniweft glass for stability.  

We built the #4 bow the same way but increased the thickness of our lam bundle. We used a back of tapered ipe, parallel osage, .030 uniweft glass, parallel osage and an ipe belly.

We drew the bow several times and were close to our weight when I decided to full draw it and it snapped. The break occured at the uniweft layer but there is glass on both halfs of the break. It is as if the glass was torn apart. We were using smooth on.

I am thinking that my long draw length also contributed and that I am going to need a 66-70" bow if we continue to use mostly wood rather than a wood core trapped between glass.

Your thoughts for bow #5?

 

[Sam Harper]

Ipe does not make a good backing.  You would've been much better off with glass, hickory, or bamboo.  If you're going to use wood on the back of a bow, the grain has to be almost perfectly straight.