I don't want to derail Joe's thread, but I did want to point out that stuff happens sometimes.
I've been promoting my Black Walnut shafts locally as good break shafts. Black Walnut is lighter, stronger (usually), and stiffer than Maple and I feel it transmits the force of the break to the cueball very well. In addition, with the relaxing of the BCA rule against phenolic tips, it can become a formidable weapon for those that prefer a lighter break cue when paired up with a single piece phenolic ferrule and tip combination.
So a local medium skill player asked me to put a one-piece phenolic ferrule/tip on an old McDermott shaft that he had to use as a break shaft. I measured the tip and it's at 13mm - not real fat, so I cautioned him that it might not hold up and I couldn't guarantee it, but he wants to try it out anyway. Last Friday I got to league early to practice, he was there and brought me the shaft that he wants tipped. Since I use 3/8-10 pins, I gave him my personal break shaft to try out on his butt. I had been breaking with that shaft for 3-4 months. He has a much harder break than mine, but I saw no problem with giving him a demo. He came back 20 minutes later with my shaft in 2 pieces. It broke the second time he hit with it! He felt REALLY bad and wanted to pay for it, but I assured him I would simply make another as I gave him that shaft to demo - I also asked that he keep it quiet that he broke it or I'll never sell another!!! LOL
Another player was watching and assured me he didn't do anything but break with it - not even that hard. Oh yeah, 3 balls went down on that break!!! :grin: So this is not a completely apples to apples comparison with Joe's experience, but in this case, I know there was no malice or anger involved.
Looking at the break, there really isn't any grain in that part of the shaft, so it probably should never have been selected for shaft wood - live and learn.
Gary