Hey everybody, I've been struggling trying to use posted gcode from Fusion 360 on a Mach 3 mill. It seem that occasionally I'll do a project that will work fine, probably 1 out of 50, The problem I'm having is that when I start to run the gcode in Mach 3 the Z axis will go up to a safe height and stop running. I figured it was the G28 that was causing this so I deleted the G28 in post. But when I run the gcode now the Z axis will raise up the come down but will be .25" above 0. It seem the the gcode will go properly from here but at the wrong Z height. Is there a setting I'm missing in Mach 3? I would appreciat any help I can get,It's very frustrating!

Bill

Hi Bill,

If you zip and post your Gcode file we could perhaps see where the problem lies.

Tweakie.

Thanks for responding Tweakie. I've zipped the file and will post it.
Thanks, Bill

Hi Bill,

Nothing really wrong with your Gcode except that Z zero is the top surface of your spoil board rather than the top surface of the workpiece.

Tweakie.

So if I use the spoilboard as zero then it should work? Everything that I've read said that zero should be the top of the work piece. I'll try changing that and see how things go.
Thanks, Tweakie. I'll let you know.

It's common practice to have Z zero as the top surface of the workpiece - at least that's what I do but somehow your Gcode file has been compiled differently.

That's what I thought, I even changed the parameters in 360 and tried it again but it did the same thing. I then set the Z zero to the bottom of the model and it worked fine. I just have to raise the Z a little before I run the Gcode. Ther was a couple of things though, the Gcode would stop and the error message was something like "The radius was not the same as the first" with a line of Gcode. Or something of that sort. I'll look it up in the manual, but if you have any ideas let me know.

Thanks, Bill

Hi Bill,

That error message refers to the IJ Mode being incorrect for the arc that is being produced - try changing the IJ Mode or better still add the G90.1 / G91.1 (as appropriate) to your Gcode file.

Tweakie.

Hi Tweakie,

I changed some settings in Fusion 360 and got the CNC to work properly. But I was still getting the radius error and an e stop just popping up. I just deactivated th pins for the estop and the limit switches and set the soft limits in Mach 3. Then everything worked as advertised. I even used shielded cable for the limit switched.

Thanks for all the help.

Bill

If you have separate home switches, your soft limits will work.
But if you use limit switches also for homing you can forget about soft limits, they will not be active.