Hi all,
Not much on the forums for posting.. mostly perusing existing problem solving :-) An interesting phenomena happens from time to time on my Bot - an ancient PRT, running from an updated control box. My machine sits on a concrete floor (well, the leg posts) and I have a 12 gauge copper wire running from one corner bolt of the rail out through the wall and onto a metal stake driven into the ground as my "ground". 99% of the time the machine runs flawlessly.. until that 1% that happened today. Much of my machine work is with Duna or Signfoam HDU board which can build up some static, but not as much as pvc. I do not use a dust collection system - I'm still working on a system that I like and I prefer to see the cutting bit while it's working. Anyway, many items I do involved cutting .stl files, which are the 2.5D dimensional images which can take hours to carve. Today, I was finishing an 18 hour job (cut 12 - hit pause, let the spindle cool down and restart next morning) which involved two passes of the cutting bit. I was there when it hit the 50% mark which is when the spindle etc would normally go back to the starting mark on the job and do the second part of the carve (depth) when the machine paused at 50%, started to make it's move back to the zero mark and stopped dead in a odd buzzing sound. No errors on the computer screen showed. But the machine started the second part of the carve where it came to a halt - obviously not in the right spot. Since I was there I was able to E-stop it and keep it from destroying a very expensive piece of material.
So, my though is that it is not nearly grounded enough, especially in times of high humidity like we've been seeing for weeks here. I've read on here that at least one member has ground straps from the spindle to carriage; Z carriage to Y carriage; Y gantry to X rails and each leg individually grounded to the table/rails. And then all that tied to a common ground plate somewhere. Seems excessive, but I get it. Does anyone have even a sketch on proper grounding - where everything should be grounded, if there is such a thing? I know metal to metal is paramount; I just don't quite know what would be considered the best way to get everything to earth.
Thanks!
Rick