If I press the Z- button on the control screen, does that simply lower the Z position by the set amount, or does it redefine Z-zero? I can’t just lower it with Z- and set the new Z-zero on my screen since the machine is in clearance mode as it returns to home. I’m running g-code over and over to slowly flatten a board. I’m watching the progress with a camera and my PC in another room. I’d like to be able to re-zero my Z after each run and then run the g-code again without touching the machine. Is this possible?
Once you zero xyz you never need to rezero. That zero is set until you change it.
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In this case I’m trying to run the same g-code each time to take off more of the piece. Each time I run the flattening program the piece has a new zero unless I modify my toolpath to start at a lower depth each time. What I’ve been doing is setting a new zero after each pass. I was hoping to find a better/easier way.
Hey Mark,
Either you create a G-code toolpath that uses multiple passes subsequently, or, if you strictly want a one-pass toolpath, I would use the 3-Axis Touch probe on top of the workpiece and probe Z, instead of lowering Z manually with -Z on Jog Pane.
No, it just moves Z. If you want to make the new position the new workpiece zero, you’ll have to click on the zeroing button for that axis, or enter
G92 Z0
into the MDI.
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There is a very simple solution:
After each cut the tool lifts by a certain amount off the material. That amount is set in your CAM software. Add the amount you want to remove with your next surfacing pass to that number and enter it in the box that displays your Z height.
Example: after the cut the tool lifts 20mm off the material or machine bed surface, 20 will be displayed in the z box. Add the amount you want to remove (for example 1mm) to that number and type it (21) in the box. That will set the Z height to 21mm. Then press rewind and cycle start and the flattening toolpath will run again and remove 1more mm.
Hey Tom,
not if the toolpath contains a Z position in absolute distance mode. In this case, if the previous coordinate system offset (workpiece Z zero) is still in effect, the machine will mill at the height where it milled the previous pass, which will be milling air. It’s the manually setting Z zero/probing Z on workpiece top/G92 Z0 that makes that it will mill the next pass at a lower height than before.
EDIT: I think you mean entering into the Z axis position value (small gear wheel button). Yes, this would change the Z workpiece zero like G92 does. This will work if you have a Z position command in the toolpath, and it will take the new Z workpiece zero when moving to the milling height. Otherwise it will have no effect, because setting a different workpiece zero value does not trigger a motion. Only subsequent motion commands for the corresponding axis will.
By the way, lowering Z means entering a smaller value. Z=19 is lower than Z=20 and Z=−51 is lower than Z=−50.
– Source: here
Your post contains a few errors, I will only correct one:
If the Z height displays 20 mm after the cut and you enter 21 in that box (you will actually reset the Z in both buildbotics as well as Masso controller by doing this), the controller will now move 21 mm downwards and remove one more mm from the material if you rerun the file.
If you enter 19 mm it will move 19 mm downwards and cut air, because the tool was actually 20mm above the material.
My post is 100% correct, I invite you to try it out yourself if you don’t believe it, I have used this method many times.
Hey Tom,
EDIT: Oh man, please excuse me. I had this so often, but this happens before breakfast before coffee and when you do too many things at one time. Tomorrow is Karfreitag, where all stores are closed, and I have so much to do today.
I could show you posts of mine where I explain it correctly.
Of course my statement is true that to enter a motion command that lowers Z has to be a value smaller than where you are. But we were not talking about the absolute position, but about entering the offset. Of course it would be bigger if you want to get the Z lower. There is an expression in German that says: I was standing on the hose. 
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