I'm sure this has been done before, in fact I've laughed over others misfortune many times, so I thought it was worth sharing. I regard myself as a decent home mechanic and can generally get everything I need done on my bikes.
I replaced the hose on my rear brake last night, it's a shimano m785, and had got it pretty much bled and feeling stif. So just a few more yanks on the brake lever to get every last little bubble out.... Gnnngh... Crack....psssss.....bugger!
Some how I've just cracked the ceramic piston with my own fair hand, mineral oil is now p1ssing out everywhere and the caliper looks proper broken.
Today I found out that shimano don't make spare parts for the caliper so I now need a new caliper, went for an SLX one in the end as they look the same and are compatible (and cheaper).
So what have you managed to destroy whilst spannering at home?