After about a week of printing, I broke my bed plate. No big deal as it was inexpensive plate glass. The break was entirely my fault and resulted from applying prying force to remove a printed object. Don't think it was related to the heat at all.

What caught my attention, though, was that the crack initiated at the edge of the glass, under a corner of one of the bulldog clips (is that really what they are called??) holding the bed plate to the heater.

In addition to learning not to pry objects from the bed, I added a small piece of silicone self fusing tape below each clip. I already had a roll that I bought for another project. The tape protects the glass from the sharp edges of the hard steel in the clips. When I need to remove the glass, or adjust the clip positions, the pieces of tape easily peel off and then stick again when reapplied.

http://www.amazon.com/F4-Tape-Self-f...ne+fusion+tape

YMMV.

Jim