I've had the sme issue since always, but learnt to live with it. Basically I unplug my VFD whenever I needed to probe (mostly in the middle of jobs, changing bits)... which is cumbersome and feels unstable, because every once in a while my controller crashes when doing this ... until... I just tried my very same cnc/controller/vfd/probe setup, except this time with my laptop, unplugged from the AC mains and voila! Time to get a USB optoisolator then. edit: BTW, and this might help other diagnose the problem. I had another issue, the trackpad of my cnc computer was unstable too. Didn't give it much thought asuming it was just "airborne" EMI from the VFD. Well, I just changed the laptop power supply's cable to an unearthed one, and problem begone. Time to resucitate my intent of having home swithces too!
I had the same problem with my XYZ probe using an HP SFF PC. When I switched back to an old Surface Pro 3 it had no problems at all. Picked up a USB in-line isolator and everything has been problem-free ever since. Thanks to everyone that contributed to this thread, most of all to Peter for putting up with all of us.
I have an X32 Blackbox that has similar problems. I have been using it for a few months now and it was all working fine. Now my XYZ Plus probe has the green LEDS on any time the ground wire is touching the spindle. I have disconnected everything from the Blackbox except for the Power plug, the Probe plug and the Computer connection to my laptop. If I disconnect the computer cord then the green LEDS go out. Im believing there might be a short in the Blackbox. I have also completely replaced every wire including the wires from the VFD, all the motor wires, all the limit switch wires and the computer connection wire. I had changed nothing from when it was all working and when it started failing. Thanks for any help.
That rather indicates a short through the PC - try a different PC, or if the computer has 2-pin power plug - try flipping it around.
Spindle should be EARTHED DC GND should be a seperate domain Having a short between the two (thats supposed to be isolated from each other - high voltage mains vs low voltage DC) is dangerous. Unplug things one at a time until probe (good test, could use a multimeter too but probe is a quick indicator of a problem) until problem clears up. Could be endstops mounted incorrectly, failing PSU in a desktop PC or Monitor, etc
Unplugging the usb from my laptop turned the probe off. Unplugged each motor limits witch didn't change anything.
Then laptop PSU might have a short. Try on battery only. Try flipping 2-pin plug on laptop PSU in socket (Neutral Earth bonds exists, if plugged in wrong way round it might leak current)
It doesn't come apart at all. With it unplugged it still have the probe lights on. So I'm assuming a usb insulator would be needed. Now. With the vfd grounded to the outlet. Where would the proper place to ground the cnc it's self? Can I go to an outlet ground at well?
Issure resolved. Wasn't my usb. I had 2 limit switch grounding out through the bolt. Added a small plastic spacer and all is good
Am I understanding this correctly. The ground for the spindle should be an earth ground and not a ground to the ground lug on the vdf?
Confirm with your VFD and spindle vendor about specifics, but usually both spindle body and VFD has an Earth (connected to mains earth) Low voltage components has DC GND And DC GND should be perfectly isolated from Mains Earth
I see steel rails, Z axis not isolated from frame like wheels would be so you have a wider area to check for DC GND (from say a limit switch) shorting to the frame or some other AC EARTH to DC GND short.
After check everything I found that I had a bad wire on my Y limit switch. It had a very low ohms reading between the red and black wires, Replaced wire and the XYZ prob work just fine. Also all limit switches as well work. This is my second machine I have build with OpenBuild and I am still learning. Thanks Doug
I have this exact issue. Afer testing I found DC ground in the controller is connecting to Spindle Earth via the V- out from the CNC Controller (CNC4Newbie C4N controller, Openbuilds touch plate) to the ACM terminal (Analog Signal Reference: ACM acts as the common ground for analog inputs) on the Huanyang 2.2 KW spindle. This is wired as per instructions and works as it should, but please let me know if there is a better way to connect controller to VFD, see my connection below. The spindle is earthed back to the VFD so that completes the circuit and therefore the Probe PIN connects when the magnate is on the tool. (Edit: I think erroneous conclusion above). I swapped Signal and GND (blue with black) on the probe and now it works when the tool touches the plate, no need for the magnate. I have CNC Controller to VFD wired as follows. CNC Controller SP Relay + -------- FOR CNC Controller SP Relay - -------- DCM CNC Controller 0-10V + -------- VI CNC Controller 0-10V - -------- ACM The CNC Controller 0-10V terminal is continuous with the controller Probe - terminal
On VFDs the inputs like ACM is isolated from AC GND, so probably not via the ACM port Workaround fine, but there is still a short somewhere, i'd try fixing it before it causes damage
Thanks for the reply, I just doubled checked with the multimeter, on my Huanyang VFD ACM is not continuous (multimeter does not beep) with AC ground on the VFD. I'll investigate further.
I think I found it. Testing continuity between controller DC ground to Spindle Earth. 1: Controller Plugged in and VFD plugged in: I get Continuity, multimeter beeps. 2: Controller Plugged in, VFD not plugged in. No continuity. 3: Controller not Plugged in, VFD plugged in. No continuity. Is this a ground loop? Initially I thought impossible because my controller has no earth coming in, only the two 24V wires from the AC to 24 V DC power supply. The VFD is US/Canada (Three wires total, no neutral) 240 V with earth. I'm obviously missing something? Thanks for the help.
I solved the issue, my old power supply was connecting the DC Ground to AC Mains Earth, I connected a MEAN WELL LRS-350-24 350.4W 24V and the issue went away, I can now use the probe wired in the normal way.
