Why the need to keep reseting Z Zero with zero plate

OK, i have noticed when I do a carve, using the Z plate, Z always starts a 19mm, after the carve, X&Y go to Zero, Z ends up at 20.32mm.

The question is why?

If I am doing multiple carves on the same piece, why not back to 19mm? rather than needing to reset zero on the z axis?

Maybe I’m not following correctly but from what you described are you sure that Z zero has changed? I ask because you never mention actually going to Z zero in your post. I’ve never paid that much attention to the height that I start and stop at and I have done multiples with a jig and not resetting any axis to zero.

I guess what I’m asking is if the machine just goes a little higher up from the work piece at the end and still has the correct zero?

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@Bill , maybe what you are seeing is where the tool goes after the zeroing, then you may also see the safe height the tool will go to when toolpath is finished with the cut.

yes, that’s what I am saying, When I use the z plate after finding zero it goes to a I guess safe height of 19 mm. When it finishes a carve and returns to zero it reads 23 mm. I guess the Z is no longer Zero, so I get the plate and zero it again.

Just to clarify I am talking about work coordinates (the big numbers in gSender) not the machine/absolute coordinates (the little numbers in gSender).

Just did a test on my machine, probed XYZ and the machine went to 31mm after the probe. Ran the job and the machine was at 20mm when it stopped. Z zero was still the same it just was at a different height from the work piece when it ended. This is how it should work. When I hit goto Z zero button it lands right on top of the work piece even thought the start and end heights are different.

If your actual Z zero has changed then something is wrong but you can’t tell that from the start and stop heights being different. The next time this happens what I would do is move the machine so the bit is not on top of the work piece anymore and hit goto Z zero. It “should” go to the right spot even if the start and end heights were different. I say move the machine off the work piece and put a hand on the E-Stop just in case, don’t want you to break a bit if your machine has a problem.

Edit: I’m running gSender 1.1.7

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@_Michael I will just reset the Z each time, that’s what I’ve been doing to date. I just thought that at the end of job, say I run three tool paths, X & Y return to zero, Z changes.

Instead of guessing, just check it. Jog down to Z-zero (not all at once), and see if it is correct.


@Bill - Michael described it perfectly. My machine operates exactly the same as he described. Whatever Z height your router ends up at the end of a cut is immaterial. It does not matter. If you click on “Go to” and “Zero Z” in gSender at the end of a cut, you will see that the router returns exactly to the 0" position. There is no need for you to reset Zero Z each time before running the next toolpath.