Newbie needs help getting my setup working

Got it moving correctly. The drivers have an annoying feature in that the microsteps are set by some DIP switches but the polarity is inverted (switch in position "ON" = 0). So I had the microstepping set at 200 instead of 2. With that straightened out and my steps/rev set to 200 (1.8 deg steppers), microstepping set at 2, and the 5mm pitch of the ballscrews plugged in it seems to be moving the appropriate distance in the test dialog. Good times.

The mill is a Grizzly G0704 benchtop mill. Very happy with it, glad to see it dancing finally .

Ok, started with my first program tonight. It's just a fake part I made up to do some testing. The first thing it does after some setup is go to Z0. This starts moving the head down past the material (I homed and touched off the material). I'm testing with a 2x4 and no cutter right now so no harm done, but I'm confused.

Here's the snippet of the gcode:

I generated this from Fusion 360. I've set the coordinate system origin in Fusion 360 to a top corner of the part and touched off that same corner.

I may be confused about things... my belief is that homing tells LinuxCNC that the machine is at its home location (as specified by the config) and touch off tells LinuxCNC the machine is at the origin of the part's program.

I've configured my Z axis to run from 0" to 11" with a home location of 11". So G0 Z0 taking it down makes sense.

Advice?

G53 tells the machine to use the G53 coordinate system (ignoring the touch off), That is the machine coordinates. in your case Z0 is the bottom of the Z travel.
If you touched off in G54 try changing the line to G54.

wiki.linuxcnc.org/cgi-bin/wiki.pl?CoordinateSystems
linuxcnc.org/docs/html/gcode/coordinates.html

Rick G

Hypnotoad wrote: N20 G53 G0 Z0.

Advice?

Set the Axis limits in the INI to 0 at the top and a negative number at the bottom.

CAM systems seem to assume that G53 Z0 will always take the machine to the the top of travel, and your machine is set up differently.

andypugh wrote:

Hypnotoad wrote: N20 G53 G0 Z0.

Advice?

Set the Axis limits in the INI to 0 at the top and a negative number at the bottom.

CAM systems seem to assume that G53 Z0 will always take the machine to the the top of travel, and your machine is set up differently.

Ok, so I've been playing with this all night and I'm confused. Which way should a positive jog move the milling machine head? Up? I set the Z axis up as below.

When I move the head to the top and press home on the Z axis and then issue a g0 z0 it takes the head down toward the table, as if HOME=-11.0. I'm super confused.

Well I sort of got things in working order and cut my test piece into a 2x4. Worked pretty well. I think what was confusing me before was I needed to enter G53 G0 Z0 to move in machine coordinate system -- I'm slowly picking up this stuff.

Something is still off about the coordinates. I think I need to flip both X and Y axes, I had to touch off on the wrong corner of the part. But that's for another night.