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Mach4 General Discussion / Z-Axis Overshooting
« on: March 30, 2017, 09:27:31 AM »
I've cut my first parts on my Chinese 6040!! :)) The X and Y dimensions of my parts are dead-on, but I'm having some trouble with the Z-Axis.
I'm using the stock stepper motor drivers that came with the 6040. I'm running a licensed copy of the current version of Mach4 Hobby on a PC with Windows10 and a PMDX-SmartBob-411 USB interface (approved for Mach4). The 411 is also at the current version. My CAM software is EstlCAM.
I'm cutting plexiglas sheet with a 4-flute, 5mm end mill. I set the top surface of my material to 0. The thickness of the plex is 6mm, so for insurance I set my cut depth to -6.25mm. I've checked the G-Code and there are no blocks with Z-values deeper than -6.25, so my CAM software appears to be working correctly.
But the Z-Axis is cutting deeper than it should. The holes in my spoiler board are 4-4.5mm deep instead of 0.25mm as they should be. I've stepped through the G-Code using "Single Block" mode, and the actual Depth per Pass of the end mill is 3mm instead of 2mm as my CAM software, the G-Code, and the DRO ALL indicate. The Z-Axis is set to +5mm before G-Code begins execution, and both the DRO and the actual Z-Axis position after the G-Code executes, return to +5mm.
However, in Jog Mode the DRO values match the actual movement of the Z-Axis. In Jog Mode the Z-Axis stepper motor rotates 1/4 turn for each mm. The Motor Configuration for the Z-Axis (Motor 2) has "Counts per Unit" set to 400. So the motor parameters appear to be set correctly for micro-stepping, at least when jogging.
My plunge rate is 600mm/min, and that is the value in the G-Code. I thought maybe that the velocity or acceleration values in the Motor Configuration might be excessive, but I figured that would cause me to lose steps and be too shallow, not gain them and be too deep.
Everything appears to be working correctly when jogging, but not when executing G-Code. Is there a parameter somewhere in the configuration that makes jogging operate differently than G-Code execution? It seems to me that the "Counts per Unit" for the Z-Axis is incorrect somewhere, but I don't know where it might be.
Any thoughts would be appreciated.
Thanks.
I'm using the stock stepper motor drivers that came with the 6040. I'm running a licensed copy of the current version of Mach4 Hobby on a PC with Windows10 and a PMDX-SmartBob-411 USB interface (approved for Mach4). The 411 is also at the current version. My CAM software is EstlCAM.
I'm cutting plexiglas sheet with a 4-flute, 5mm end mill. I set the top surface of my material to 0. The thickness of the plex is 6mm, so for insurance I set my cut depth to -6.25mm. I've checked the G-Code and there are no blocks with Z-values deeper than -6.25, so my CAM software appears to be working correctly.
But the Z-Axis is cutting deeper than it should. The holes in my spoiler board are 4-4.5mm deep instead of 0.25mm as they should be. I've stepped through the G-Code using "Single Block" mode, and the actual Depth per Pass of the end mill is 3mm instead of 2mm as my CAM software, the G-Code, and the DRO ALL indicate. The Z-Axis is set to +5mm before G-Code begins execution, and both the DRO and the actual Z-Axis position after the G-Code executes, return to +5mm.
However, in Jog Mode the DRO values match the actual movement of the Z-Axis. In Jog Mode the Z-Axis stepper motor rotates 1/4 turn for each mm. The Motor Configuration for the Z-Axis (Motor 2) has "Counts per Unit" set to 400. So the motor parameters appear to be set correctly for micro-stepping, at least when jogging.
My plunge rate is 600mm/min, and that is the value in the G-Code. I thought maybe that the velocity or acceleration values in the Motor Configuration might be excessive, but I figured that would cause me to lose steps and be too shallow, not gain them and be too deep.
Everything appears to be working correctly when jogging, but not when executing G-Code. Is there a parameter somewhere in the configuration that makes jogging operate differently than G-Code execution? It seems to me that the "Counts per Unit" for the Z-Axis is incorrect somewhere, but I don't know where it might be.
Any thoughts would be appreciated.
Thanks.