In an earlier post, I pointed out some maintenance I needed to do. Last week, I took off my crank as part of that, and it broke. I had probably over torqued it, and it finally let go when I removed it.
Discussion with friend Dave C suggested what the problems were; I'd probably been slightly overtorquing, but doing it over and over each time I replaced the crank, and I was probably also reading the wrench wrong.
I've got a new crank, and I'm being much more careful with the torque. I've also marked my instructions with the torque values, in foot-pounds, on the instructions I use. No more on-the-fly trying to convert newton-meters, or even inch-pounds.