hy / if there would be a device, that would measure the distance between the part and the tool, than also there must be a "decisional process" within that device, that should take a decision
this "decisional process" will behave conditionally, and the "limit value" should vary from tool to tool, from operation to operation, thus that "device" should comunicate with the "program"
fact is that the "device" will always be one step behind the program, thus the machine will try to move, and the device will analyze that movement after it has begin
there already exist such "devices" that work one step before the program, that the device analyzes the potential movement, and if all is ok, than the program is allowed to continue
kindly
ps : 0:43 is wrong is terrible wrong - there are real situations that lead to cnc crash, without being the operator fault; in mass productions, stuff that happens only once at thousands (eq) of parts may lead to signifiant downtime, missalingments, etc ... there is always a 1st time for everything