I have a new LR4 build with Jackpot, just doing initial squaring and levelling, and following the docs, which suggests a ‘G38.2 Z0’ for Z probing
But this seems to send my Z platform up to home, and not down to the probe
It homes fine, so direction seems ok
The probe works - LED is off, and if I touch the probe it stops motion (and LED comes on)
My workaround is using ‘G38.2 Z-20’ to tell it specifically to move down to probe, but I wanted to check if I’m missing something or if it’s something to worry about?
Just my two cents. I believe the reason for the Z0 in the example is to make sure that the Z axis does not move. No one knows where the end user’s axis is at the time of testing. Most all examples I have seen use a 0 for this reason. Or they explain each line of code in detail as shown in Jason’s reply.
My understanding is that it is “Probe towards Z=0” since the LR firmware sets the Z to a value of 200, this will mean downwards more than the axis is actually capable of travelling after homing. Personally, I have my probe macro set to Z-200 which definitely is lower than where it currently is.
I try to always remember that not everyone who reads this content will be using this particular machine/firmware combo nor may they have 14 years of playing with manual gcode programming. Z=0 of course is not a fool proof way of protecting a “new” user from perhaps ruining a “new” machine when he does not actually understand the operation of said machine. Imagine for a moment, machine not using homing, probe plate not positioned, a small tool diameter. z=-200 or z=0 in this case “might” have very unintended results. IMHO I just believe that a z=0 or perhaps z=-2mm/.080in would be a safe place to start, just to see that the probe command is entered and operates correctly .