zlacker

>>ummonk+(OP)
Servo based systems are both incredibly power and incredibly fast. So fast that if you've never seen a servo based arm move at top speed and come to that top speed at top acceleration you'd be forgiven to think that I'm exaggerating.

Depending on the application there are different layers of safety surrounding these systems, including perimeter guards, optical barriers, limit switches, resistance based detection and so on. But when a system is broken someone has to go in and fix it, and you tend to do that with the robot powered up, some of the safety systems disabled so you can actually work on it and if you're really unlucky a motor will end up shorted against a + or - rail while you're within reach. This is obviously dangerous, and it is more dangerous because broken equipment can't be trusted to behave in a predictable way.

They won't stop. Not until whatever is obstructing has moved or the motor has burned out (or someone has the presence of mind to hit the e-stop). I've seen a 3" thick mount that must have weighed well over a ton sheared clear of its bolts (which themselves were an inch thick) by a malfunctioning servo on a very large lathe under construction (think 8 foot chuck for crane cable idler wheels). Do not fuck with servo systems unless you are 100% sure they are safe to approach or you may well end up dead or gravely injured.

>>jacque+65
I just want to echo the 'so fast you'd be forgiven to think that I'm exaggerating'. I work with industrial arms every day, but pretty much never with them running at full acceleration up to the speed limit between the extents of reach. Even when they bump you at a speed that would be like a mild shove from a person, the unyielding force is remarkable, and if you're ever near one and surprised by a sudden 'full send' motion, it's terrifying.

>>yakz+va
Terrifying is the proper term. The only time I've ever been really mad with a co-worker is when they decided to do a demo to potential customers with the newest (pre-release) firmware of a massive lathe without my very explicit permission. That could have well ended up with people seriously injured, as it was - of course - it happened to have a pretty bad bug in it but besides people getting scared it didn't cause any damage or injury.

My own process to ensure things were safe was to first run it in air without the spindle powered up, then on foam, chalk, and finally on aluminum in that order before progressing to steel.

And that saved my ass more than once.