Funny story about crushing fingers (Seth, remember this?)
When I was like 11 years old, my brothers and my dad were splitting wood with a hydraulic log splitter. It was owned by a friend of the family, Blake. Blake had the job of loading the logs into the splitter, because my dad didn't want one of us getting our hands caught or cut by the blade. I was the lucky SOB to operate the lever which started the pump and in turn pushed the piston causing the wood to press against the blade and split.
Blake is loading a log, Jeremy is off in La La Land, and I pull the lever while his hand is still between the backing plate and the log... in a panick, I didn't remember that to reverse the plate, one needed to release the lever and pull back on it... needless to say the poor guy's hand was crushed. I was lucky that he didn't file...
Moral of the story - don't let an 11 year old operate dangerous machinery, even if they "prove" to be responsible/reliable.