Thc disable

For #1, I did it with a marker secured to the torch, and flat piece of material (cardboard, etc would probably work ok), just need to make sure it's at least as big as the square you have, and that it does not move:
1. Home the machine.
2. Draw a line in X.
3. Draw a line in Y. 90° to the line you just drew in X 
4. Use a square to validate how square the "L" you just drew is.
5. If it's not square, you have two options, adjust the position of your homing switches, or adjust the "HOME_OFFSET" in the INI file to suite.
6. Restart LinuxCNC.
7. GOTO Step 1, repeat until it's square

For #2:
1. Jog axis in the one direction only.
2. Set up dial indicator or some means of measurement on the axis and zero it. Make sure the indicator has enough travel to absorb movement from next step.
3. Open MDI and command a move in the direction you jogged in step 1.  Move it an easy to measure amount that is within the amount the indicator can measure.
4. Verify the indicator moved the amount you commanded.
5. If it did not, you can adjust your step scale in the INI for the axis you are verifying (more steps = further distance, less steps = less distance, the amount it changes depends on the mechanical components on your table).  Don't forget to change it for each Joint associated with the axis.
6. Restart LinuxCNC
7. GOTO Step 1, repeat until the commanded move length and the measured move length match.

Both of these processes assume that all of the mechanical connections are tight and sound and good to go.  If any thing is loose, or causing excessive backlash, you will also end up with holes that are not round.

Looking at your config, it looks to me like you do have 2 steppers for Y, and I saw two entries for inputs for Y MIN-HOME:

So I assumed you had two steppers and two limit switches on Y.  Yes, you need that to do what I described in process 1.

No, you are adjusting the Y axis to the X axis.  

By changing the position of the limit switch (or changing the offset in the .ini file), you are changing where the homed position is for each individual stepper in Y, which will cause it to square the gantry.  Once that happens, the Y axis becomes locked together, and the steppers are no longer independent.  

This will help you understand (although this is not linuxcnc, nor a plasma machine, the principle is the same):

I think you’re asking how far to move the switches?  If so I just did it with trial and error until it was square.  You can also change the offset value in the ini file if you didn’t want to physically move the switch.  I’ve not done the second one, but Tommy says it works, and I trust Tommy

did you check the movement distances?

I think there is a linuxcnc tool to do it for you but I’ve never used it.

for steps it’s (distance commanded/distance moved)*step scale = new step scape 

the squareness is trial and error 

snowgoer540 wrote:

 I’ve not done the second one, but Tommy says it works, and I trust Tommy

I have 3 machines in the shop, two more on client sites that i have built and use .INI squaring in use daily, and another 2 industrial retrofitted ones,one of them still on 2.8PRE since when that came out. Must have been very lucky on this last/first one as i edited the hal and ini by hand and got it working in about 10 minutes ... after dealing with the fear of "how do i do joints now?" Now takes even less, takes more time to measure and home the machine.
In general, mark the 4 corners on a plate/table/sheet/ply (using a laser makes this a breeze), measure the two diagonals, calculate the difference, figure out what side is best to move, edit ini by entering HALF of the difference to one joint, check again, chances are it will be spot on.