User error. A buffer has no mind of its own.
I think what happens is that the mind of the operator wanders.
That's the case in the majority of shop accidents.
Everything Salem said.
I forget for a number of people that knifemaking is their introduction to manufacturing, metalworking, or any industrial process. But every accident I've seen or investigated or had happen to me has been the direct result of someone, usually the person injured, not paying attention to what they are doing because they are either complacent, or unable to think critically about the process and avoid getting into danger.
Buffing is no different. A buff is a soft wheel. Soft wheels grab sharp edges directed against the rotation of the wheel. Therefore keep sharp edges pointed with the direction of the wheel. That's pretty simple algebra.
When I broke my finger drilling a hole, it was because I was drilling into an existing hole and did not use a clamp or a stop bolt, so the part helicoptered and took my ring finger with it. Contrary to popular belief here, drilling without clamping is not inherently dangerous, there are many things you can do to mitigate the danger, such as paying attention to when your drill is going to break through the material and reducing the force you're feeding with, or, in plastic materials, stoning the web of the drill flat. But drilling into an existing hole larger than the web of the drill is never ok without a solid setup because there is no inherent axial resistance on the web of the drill preventing it from corkscrewing in. I knew that and did it anyway because I was in a hurry.
When I broke and degloved my index finger in a brake press, it was because I was tired, the work was mind numbing, and I had checked out for the night. So I didn't even notice that my finger supporting the part in the fixture was under the part, between it and the fixture, when the ram came down. Nothing inherently dangerous about the fixture or the machine. Lots of inherent danger in not paying attention to what I'm doing.
People wail and gnash their teeth about dealing with long stringy chips from turning low carbon steel, as if simply looking at them will cut them to shreds. I remove them from parts, from chip beds, from anything that doesn't require much force by hand, without a glove, and never get cut, because I pay attention. Because I know they're sharp, and that if my grip slides, they will cut me no matter if I was wearing a glove or not. So if they take any force to remove, I use a pick or pliers.
I'm just using examples of myself here, but in nearly 20 years of working in foundries, machine shops, weld shops, factories, I've yet to see an accident caused because something was "inherently" dangerous. 100% user error.
