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General Mach Discussion / Z Axis will not go below about -1mm when running - but thinks its going deeper?
« on: December 30, 2016, 11:02:08 AM »
Hello.
Ive been having a problem with my diy built cnc router today and was wondering if anyone could help me?
It normally runs fine, and it cut the first panel fine this morning, i then re skimmed my vacuum bed and tried to cut the 2nd panel, the first operation is drill a load of screw holes but when i start the program the cutter stops just below the surface of the plywood, the DROs keep counting down to -15.5mm like it should then it retracts to what it now thinks is a safe z of +5 and gos too far and hits the limit switch.... So as it has not moved down when it should have done i have to re set the z zero to try again...
I have tried restarting mach 3 / the PC, resetting the driver boards etc and making new g code, (i have had this issue before about a year ago and this seemed to get rid of it, but today it just wont have it...) Sometimes by resetting i have managed to get it to drill 5-6 holes and then it just has the problem again... I dont think it is a mechanical issue with the machine, it was running for several hours yesterday with no issues, i know it will plunge cut fine at that speed, the issue seems to be with the control or the computer, or with mach 3.
The only thing i can think of that changed between cutting the first panel and the 2nd panel is i skimmed the bed, so when i came to set the zero point for the 2nd panel it was 1mm lower. I use work coordinates and dont really use the machine coordinates or soft limits, i rely on my limit switches, i increased the soft max and soft min anyway but it made no difference...
I really dont know what is causing this, like i said it does it pretty much all the time, sometimes it will drill a few holes then do it, i read in another thread about issues with the parallel port driver not driving the break out board with enough current, but i can jog about fine i have no issues going below -1mm...
I was thinking it could be an interference issue as its only happening when the spindle is running, but ive just tried running the program with the spindle and inverter switched off and it still has the same problem...
Can anyone help?
Many thanks
James
Ive been having a problem with my diy built cnc router today and was wondering if anyone could help me?
It normally runs fine, and it cut the first panel fine this morning, i then re skimmed my vacuum bed and tried to cut the 2nd panel, the first operation is drill a load of screw holes but when i start the program the cutter stops just below the surface of the plywood, the DROs keep counting down to -15.5mm like it should then it retracts to what it now thinks is a safe z of +5 and gos too far and hits the limit switch.... So as it has not moved down when it should have done i have to re set the z zero to try again...
I have tried restarting mach 3 / the PC, resetting the driver boards etc and making new g code, (i have had this issue before about a year ago and this seemed to get rid of it, but today it just wont have it...) Sometimes by resetting i have managed to get it to drill 5-6 holes and then it just has the problem again... I dont think it is a mechanical issue with the machine, it was running for several hours yesterday with no issues, i know it will plunge cut fine at that speed, the issue seems to be with the control or the computer, or with mach 3.
The only thing i can think of that changed between cutting the first panel and the 2nd panel is i skimmed the bed, so when i came to set the zero point for the 2nd panel it was 1mm lower. I use work coordinates and dont really use the machine coordinates or soft limits, i rely on my limit switches, i increased the soft max and soft min anyway but it made no difference...
I really dont know what is causing this, like i said it does it pretty much all the time, sometimes it will drill a few holes then do it, i read in another thread about issues with the parallel port driver not driving the break out board with enough current, but i can jog about fine i have no issues going below -1mm...
I was thinking it could be an interference issue as its only happening when the spindle is running, but ive just tried running the program with the spindle and inverter switched off and it still has the same problem...
Can anyone help?
Many thanks
James