Not woodworking but in industrial butchery.
Given the job of cleaning a sausage press, which is a vessel you put sausage meat into and a hydraulic ram forces it up and out a nozzle, on which you place the gut. Its a 415v bit of kit, about 5' high about 18" in circumference and made of thick stainless steel, with a thick(about 5 inches) lid. Basically a big pressure vessel.
To stop the water coming out the hole the nozzle screws into I hammer in a round nylon wedge.
I fill with boiling water, slide over the big lid which hydraulically seals itself, then operate the knee switch(which allows both hands free to tension the gut to fill the sausage casing)
It starts to make a whirring sound. Unfamiliar as i am with such a machine of this size i bump the knee switch a few more time, still get a whirring sound
very odd, so i press the knee switch fully on and BANG, the fking nylon wedge flys out the hole like a fking missile and goes right through a chiller wall which was about 20' away, missing my head by inches.
Lesson, dont fill a pressure vessel full of water, seal it than ramp up the pressure. Lesson truly learned
Finish cleaning it and wander off, not saying a word about the 8" hold in the wall. Nowt to do with me guv