Bow explosion....

[AKmud]

Last night I was tillering a birch board bow and it was looking great.  I had used the long and short tillering strings and it had great shape and I was getting really good limb movement.  I went to brace the bow and without warning it came apart on me.  

I'm guessing I was just going a bit too fast and my string may have been too short for that initial brace, but I know I had more limb movement on the tillering tree than what that string was asking of it.     :confused:

What most likely went wrong?  Is white birch (paper birch) a decent wood for a bow?  It looked promising while I was working on it.  The wood was native Alaskan birch and was kiln dried.  I'm thinking about starting another, but if it is a problem with the wood, I won't waste my time.

[Pat B]

What method were you using to brace the bow? If the push/pull, you may have put uneven pressure and overstressed the bow. Birch isn't a very strong in tension wood so over stressing one area could result in a break.
  You have to educate the wood and early in the process, uneducated wood can cause problems if pushed.

[AKmud]

That is probably what happened.  I wasn't using my stringer since it was moving really well and I hadn't worked on the tips yet...Lessons learned.

I got another piece of the same board today to give it another try.  I usually flex the bow about 30 times every time I remove wood while tillering but I will definitely spend more time working the wood before I go to brace it.

[Pat B]

How is the grain on your board. You may want to back it as insurance. Silk, linen or rawhide will work for a backing.

[Roy Steele]

I say 98% of board bows need to be backed.

[George Tsoukalas]

A properly chosen, straight grained  board need not be backed because it is a board. A backing is suggested for beginners though and if the grain is  not good. It's about the angle of violations and the draw weight wanted.  There's more on my site. Jawge