If an axe could detect your thumb was in the way, it would no longer be useful. There's a balance. Sometimes it really is up to the operator to maintain safety

If an axe could detect your thumb was in the way, it would no longer be useful. There's a balance. Sometimes it really is up to the operator to maintain safety. Sometimes the machine can handle it. IMHO, other than reliably finding zero, everything else is up the the operator. The tool doesn't REALLY know how big it is or how fast it's going (just what it was told), and even if it did know, some operator would screw it up assuming that the tool was smart enough to adjust itself.