When my machine is cold in the morning I have to reset most the home limit switch positions and then latter in the day put them back when it warms up.  I have XYZ fixtures to position a dial indicator to see this error.

My question is...  I can't find the command or a procedure to set the axis to home/zero manually using the error amount I know from the indicator.  I can put the axis where they should be but I can't make it reset (call it home or machine zero) to this position??

Or......  I have X when set with the limit switch, it is .006 off, can I make the machine reference .006 from this position, Thanks

You can enter a "Home Offset".
 When the homing sequence is finished, this value will be automatically entered into the Machine Coordinates DRO.

Or, you can disable the HOME switches in INPUT SIGNALS and all axis will be homed and zeroed in there current position when REF ALL  is hit.


edit: forgot to post the prepared pic 

Thanks for the help

Worked Great, Spent the day working within .002 instead of .005+ (multiple large 2 sided 3d carvings with parting lines). I move to my measure location, noted the error with a dial indicator, moved to home, nudged the axis and hit ref all.

For now I'll just leave the home switches disabled and manual home at startup, then reference as above.  I thought my machine was sloppy or very temperature sensitive, but it was just flaky proximity sensors. How close can you get with a good 12mm barrel sensor? The drawback I see is not being to do a G28.1 within the G code to pick up lost steps (30,000 line code)  Thanks again Edward

Not flaky, just not nearly accurate enough for that purpose.  Does your machine have dials on each axis? If it does home it then look at the dials and write down the values on a post-it.  To get the machine back exactly on location after a fail of some sort just put it back to the dial settings hit zero, and you'll be right there to within a couple of tenths if your eye is finely calibrated to interpolate between lines!

I have sharp marks at home but try to turn off the machine at home each night and then reference all. Then I move to a dedicated G position that is fitted with fixtures to accept a metal block with an indicator attached to read the blocks. When there I can read and note the error, go to home, nudge as needed and hit reference.  When I go back to my dedicated G all are dead on. I keep checking this position threw out the day. If I crash I set to my home marks by eye (I only need to get close enough to prevent misreading the indicator by 1/10 inch.

Eventually I want to place the measure point mid axis (all three) to halve the error and use the home position offsets in the Mach3 limits menu to eliminate  the go home step and the note the error step. Then I could just go to my G position and hit reference. Note: UNTESTED