The details make perfect sense… fixture failure. Sigh, it happens to all of us…
The 2.2 KW spindle puts a lot more torque on the stock than a 600-800W spindle. Your tabs not being sufficient explanation makes double sense with the new spindle. Your work flow expectation wasn’t calibrated to the new reality. You need bigger/better tabs.
Ever wonder why machining vises are so expensive? $2K is not uncommon. Now you know. Massive overkill prevents this kind of thing.
I glad to hear the damage wasn’t so bad. As I said earlier, I’ve seen things go REALLY BAD with costs about US $10K. Tool destroyed, spindle shot, vise bent, stock wasted, machine out out of square…
Just a reminder to everyone. Do not leave a CNC machine running unattended. They are a fire hazard. I know someone who burned down his detached garage leaving his CNC machine running when he walked away. Alway stay without ear and eye shot.