I am upgrading an old Next Wave CNC Shark HD3 with an X32 Blackbox. I hope to use the existing 4-wire steppers but as I was about to start the process of changing to the connector for the black box (the Shark has what appears to be a 9 pin RS232 connector for each stepper). I noticed that it has a 5th wire that is connected to one of the bolts that connects the stepper to the machine as in an earth. Not sure if this was just extra protection or if the steppers that Next Wave used require that. Is it perhaps for RFI noise? Anyone ever seen or used a ground/ earth done this way on a stepper? Note that the Next wave machines uses HDPE aluminum stiffeners for some of the supports so you cannot simply ground the machine in a single point so perhaps they did that as an extra safety measure. When I continuity test between the stepper body and the ground on the plug from the old NW control box it does show continuity so it is definitely earthed which seems weird for what I assume is a DC stepper. Since the Blackbox is powered by 24v DC there is no no earth connection. One option is to connect these stepper grounds to the 24v power supply aluminum case. Another is to connect to the grounding bar I added when I wired my VFD for the spindle, though I am concerned about RFI noise. Any thoughts would be appreciated.
Can usually be left disconnected (BlackBox is quite filtered against EMI), but if you do want to earth them, a dedicated earth spike outside the shop, for all things CNC (shielded cables, dust hoses, dust collector, etc all starred to one central point (busbar) and then off to the earth rod) is the way to go for that
Thanks, Peter, Since the power supply case is earthed through its power cord (I checked), would it be okay to connect these earth wires to the case to achieve earthing or is that not a good idea?
In a sense, AC Mains "earth" is more of a neutral bond / "CPC" as its called in the EU. Ideally a separate spike as you want to conduct static from the dust hoses, EMI around DC components etc to GND - its not dealing with the mains side at all. IF you need it. I'd skip it at first, BlackBox is quite filtered against EMI
Thanks. For now at least, I do not plan to connect the ground wire. If I have problems for some reason, I will report back.
docs:blackbox-x32:faq-emi [OpenBuilds Documentation] will be more helpful, simply spacing noise sources away from affected devices is a far simpler solution for example.
