60x60 pro, mach 4. I’m pretty new at this, but I have had about a dozen successful jobs on this machine. I’ve had this problem occasionally; After a tool change, after setting Z on the touch plate, the spindle rises 2”, and Z shows to be 2”. When I start the job I hear the “clunk” and Z now shows -198, with the error; “Z commanded over soft max”. Usually I just reset Z to 2” and try again and it works. Now, on a new job, after the tool change and re-setting Z, the spindle moves a few inches to the right, then “clunk”, Z jumps to -198”, “Z commanded over soft max. Resetting Z at that point has been problematic. I’ve tried a few times, with the same results each time, the spindle heads to the right a few inches, as it should, then clunk and -198”, “Z commanded over soft max”. Any helpful thoughts?
Sounds like you’re on Mach 4… I’d start by going through the troubleshooting steps here: Mach4 CRP800 Controller - Troubleshooting
Thanks Eric, I always appreciate your attentiveness to users needs. I could not find anything applicable in the troubleshooting guide, but it did remind me that I had originally wondered if the dust collector was the cause, and before I asked for help I had checked the hose grounding to the collector with a meter and found one section was indeed not grounded, yet still the problem persisted. Now with your reminder, I insulated between the hose and the control wire coming out of the spindle that the hose was laying against and tried the job again. Now Z jumped to -195.8415 instead of -198 as it always had previously. This was good news. Then I insulated between the hose and what I assume is the controller on the spindle, and tried again. Now Z jumped to -199.0157. Again, this seemed like good news. So then I disconnected the hose completely, almost giddy with the prospect of confirming that the hose was the issue. I ran it again. Z jumped, again to -199.0157… Poop. It was not the hose. Back to the “drawing board” I went and got rid of the 1/4” drill tool-path and changed it to a profile cut inside of a 1/4” circle with a 5/32” cutter, that would eliminate the tool change that the machine was not able to get past. Now, less giddy, but still hopeful, I ran it again. Z jumped to -198, my old friend. I tried a few times just to confirm consistency. Each time, from the cycle start, Z would jump to -198 and with a “clunk” progress was halted. This was an improvement from before when the spindle would move a few inches along X, even though Z had jumped from 2”. When I tried just punching in 2 to correct the errant Z value, after the x-ward travel, and let the cut continue, I found that the machine had lost track of X. But now that the clunk happened at cycle start, I decided to try my old standby of just punching in 2 to correct the -198… and it worked. Then I tried 3 times in a row and the machine consistently worked with no Z-jump. I hooked up the hose again, and still it worked. Using the scientific method I have determined that I have no idea why it does this Z-jump thing, but I know that if there is no movement before the clunk I can just punch in the correct Z height and carry on. If there is any movement first, I can not. Thanks for caring even if you have no answers for this anomaly.
It’s probably worth noting that controllers like this are a lot dumber than a lot of people realize…
The controller cannot tell at all where the motor is. All it does is send out step signals, and the motor moves. The controller never actually knows where the motors are, or if they got there.
I’m not sure if you’re in inches or MM, but if you’re at -198 inches that’s far outside what is physically possible for the machine to move. So the software “thinks” the motors are there, but clearly they are not.
Have you tried re-homing the machine and running this job? Because it sounds to me like the machine has lost it’s home position..
If you’ve already done that you might just want to re-install Mach fresh. Perhaps the software got corrupted here…