Need some help here.

[terry1956]

Hi, I converted a lathe to cnc. I am using centroid acorn c12 board and software. However I keep hitting the same problem.
I have homing switches on the lathe. When I start the lathe I home the machine. Then I enter the material for the part I wish to machine. I run the tool to the material face, set the z axis to zero and save, then not moving off the z position I set the tool on the x axis and set the material diameter in software. So at this point, the tool is at the starting point of the program. However when I start the program the tool just starts heading back along the z axis in the positive direction until I need to stop the machine.
I have tried a few g-code programs and at the start the tool just travels back in the z positive direction.
What have I over looked, and what is the answer?. Thanks

 

[IVGrbn]

It's a very common mistake when setting up G-code on a lathe, especially with a new control, and it's almost certainly the initial G-code block in your program. Your Z=0 and homing are likely correct. When you start the program, the first motion line is typically a rapid move, like G0 Z0.1 or G0 Z1.0. On a lathe, positive Z is away from the material, so the machine is simply moving to that safe, programmed starting position. I suggest that you run the program and watch the Z DRO. If the rapid move stops exactly at the programmed Z value, the code is fine. If it keeps traveling past that point, then we look at a deeper issue.

 

[terry1956]

Hi, yes it turned out to be the g-code. For some reason fusion360 added a command for a tool change at the beginning of the program. So the machine was sending the tool off to a location unknown along the Z+ axis. Thanks for your help.

 

[ClericSerena]

That “runaway in Z+” move usually means your G-code’s trying to go to machine zero, not part zero. Double-check your active offset like if the screen says G54 but you set zero in G92, the controller ignores it. Make sure you’re consistent about which offset you’re using before starting the run.