> A cordless handheld drill is hardly a tool that most people would call 'hazardous'. You turn the trigger, the thing rotates, grab the chuck and you can likely stall it. But that much energy in something driven by code is extremely dangerous, it's waiting for any of who knows how many conditions to take off, a common one is that putting your hands in/on something that seems to be not moving can 'make' a sensor and the machine will take off.

A friend needed a valve cover gasket changed on his Honda, and his wife needed to use the car for her Uber runs that night. He came over and instead of our usual hand tools I put a socket adapter on my 20V drill to speed up disassembly. I handed the drill to him and told him "start on the lowest torque setting, and move up in small steps."

I turned around to grab more tools from the toolbox. A minute later, I heard a loud noise. I turned to see the car's windshield cracked and a shocked look on my friend's face.

My friend was used to his renter's power drill. He hadn't anticipated how much torque a modern contractor's drill outputs and set the torque to the maximum setting. On the third valve cover bolt, the drill had caught on the bolt head and spun my friend around, smashing the battery into the windshield.

There's a piece of paper taped to me toolbox called "List of things <friend's name> may not attempt unsupervised." It gained a couple of entries that day...