G30 S-2 not working anymore?

Julek · 2 Nov 2018, 04:48

Can somebody confirm that "G30 S-2" for manual Z probing of the tool offset is still working? I am using the latest 1.22 release. The offset seems to be added with the wrong sign and does not produce the same results as:

Home all
Drive nozzle down to grab the piece of paper at x=0, y=0.
[For this example it happened at z=-15.5]
Send "G10 P0 Z15.5

described here set tool offset to current position

Julek · 2 Nov 2018, 12:57

I found a post here where @dc42 asked if the tool offset was set in the correct direction but it seems nobody responded. So maybe the implementation is incorrect and sets the offset in the wrong direction. This is also consistent with my observations, as when I manually touch the surface with "G30 S-2" at Z-50 and run G1 Z0 the head moves to the upper end stop instead of staying in place as is should. When running G1 Z-100 the head touches the bed again. This implies that the offset is added in the wrong direction.

dc42 · 2 Nov 2018, 13:04

I will check this before I do the 2.02RC4 release.

Julek · 2 Nov 2018, 15:27

Thank you. For now I found a workaround that also allows me to set X0 and Y0 as well when probing for the lower left corner of a milling workpiece.

Switch to the 1st coordinate system with "G54"
Move to the workpiece origin
Run a macro to set the workpiece origin:
G10 P1 L2 X0 Y0 Z0 ; Reset offsets
G10 P1 L20 X0 Y0 Z0 ; Set 1st coordinate system origin relative to current position
G1 X0 Y0 Z0 ; Update display

However this raised another bug. When I work with the workpiece coordinate system, move commands reaching outside the machine coordinate system trigger a unwanted negative Z movement. E.g. G1 X-60 when the machine axes minimum is at X-50, a negative Z movement is performed. I do not really want to start a milling job with this behavior ...

Am I on a completely wrong track here? I want to manually fix the origin of a workpiece and at the same time prevent movements outside the axis limits. It seems strange I am the first having problems with this.

dc42 · 3 Nov 2018, 11:26

I will check this too before the 2.02RC4 release.

dc42 · 11 Nov 2018, 10:52

There are two issues with G30 S-2. It sets the wrong sign for the tool Z offset, and it doesn't update the user position. I will fix these in 2.02RC4.

dc42 · 11 Nov 2018, 11:20

@julek said in G30 S-2 not working anymore?:

However this raised another bug. When I work with the workpiece coordinate system, move commands reaching outside the machine coordinate system trigger a unwanted negative Z movement. E.g. G1 X-60 when the machine axes minimum is at X-50, a negative Z movement is performed. I do not really want to start a milling job with this behavior ...
Am I on a completely wrong track here? I want to manually fix the origin of a workpiece and at the same time prevent movements outside the axis limits. It seems strange I am the first having problems with this.

I don't understand the issue. One of my machines has the origin at bed centre and X axis limits of -150 to +150mm. It behaves like this:

If I have no tool or workplace coordinate offset, then the firmware limits the movement to X values between -150 and +150mm.
If I now send G10 L20 X10 to set the origin 10mm right of bed centre, the allowed movement in user coordinates is -160mm to +140mm, so that the allowed movement in machine coordinates is the same -150 to +150mm as before.
If I reset the origin to be bed centre by sending G10 L20 X0, I am back to -150 to +150mm allowed movement in user coordinates
if I select a tool with an X offset of +10mm, then as the head reference point can move from -150 to +150mm, the tool can move from -140 to +160mm. So those are the limits applied to user coordinates.

I don't see what's wrong with this behaviour; however, I am not a CNC machine expert.

Julek · 22 Nov 2018, 21:46

@dc42
I updated to RC4 and everything works as expected now. Also the strange behaviour, when I was setting workpiece coordinates, is gone. I hope that I did not mix different firmware versions of duet web control and reprap when trying to resolve the G30 issue. I can tell it was there from two marks in the milling table

However everything works excellent now. Thank you very much!

jckray · 18 Jan 2019, 01:22

I'm currently working on a tool offset measuring script, but have an issue where the offset seems like it should be negative but is giving a positive value.

@dc42 can you confirm that this is fixed in 2.02(RTOS) (2018-12-24b1)?

@Julek would you be willing to share the script you had success with?

dc42 · 22 Jan 2019, 11:51

@jckray said in G30 S-2 not working anymore?:

@dc42 can you confirm that this is fixed in 2.02(RTOS) (2018-12-24b1)?

Yes.