With Probe Why use Homing?

It seems to me that I might as well turn off homing if I am using a probe.
The probe sets the XYZ I need and changes the values just set by homing.
Or am I missing something important?

My understanding is that homing tells the machine where it is relative to… er, itself (where the spindle is with respect to the frame of the machine, in effect). Probing tells the machine where the spindle is with respect to the work. If you don’t home, the machine can think that it can move further than it really can, leading to crashes (or, on the other side, soft stops inside the actual range of motion).


home sets the machine start point, probe locates the workpiece, the rest is basically mathematical operations giving you a preditable outcome to each project.

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When all 3 axes have homed, the readout in Carbide Motion will be set to −5,−5,−5 (or 0,0,0, or some other set of values which shows the offset from the working zero) and your machine will be in the back right corner.
Then you rapid to the left front corner and run the Probe sequence.
After the probe finishes the XY are set to 0,0, and the Z to top of workpiece.
After running the gcode the spindle is moved up to mid-left position.
Going to JOG causes the machine to home once more.
The homing is a waste of time.

With homing off you just turn off the machine, move the spindle to your workpiece, turn it on and run probe. That is it. No homing required.

Anyone disagree with my thinking?
Please set me straight.

Homing the machine establishes an absolute reference point.
You can absolutely do what you say by running the machine without homing, but you lose that absolute reference.
Your homing switches are at MACHINE position 0,0,0. Your WORK origin (of which there can be many) is defined as some offset from that MACHINE origin.
A short list of reasons why I prefer using absolute, repeatable reference switches (others might add):
If I am running repeat programs or programs with the same work zero, I can just home and carve.
If something goes wrong, I can just home and re-carve.
If I am using 6 tools, I can home, set Z and carve.
I can use G28 & G30
I can use absolute machine positions (example: a stationary probe location off my work)
I can raise my Z to 1mm below the switch to get it out of the way on job completion
I can use soft limits.
I can carve away my original work zero and still recover the carve or change tools.
I can use fixturing jigs in specific locations in my work area.
More things maybe?


I would add to the list the very real possibility of crashing your machine.

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