Weird Z axes movement from - to +

MortenMod

@jay_s_uk Ahh I see. Changed the homez but still does not solve my problem. As said I can move G1 Z-30 or Z-40 etc. This works fine. But every time I do a move in the opposite direction It just go to endstop no matter what I am typing

jay_s_uk

Theres nothing I can see what would cause that.
Are you using the ooznest DWC version?
And are you just using the jog buttons to make the movements?

MortenMod

@jay_s_uk I am typing in the g-code command. If using the buttons it work fine.
Need to check the other question. Will Come back later.

jay_s_uk

What are you typing in?

MortenMod

@jay_s_uk just in the command line in Web duet control. But I have the feeling that it this also provoke an error in offset probing.

jay_s_uk

I meant what commands are you typing in
Just purely G1 Z5?

MortenMod

@jay_s_uk Yes. Purely G1 Z-10 and then another one eg. G1 Z5

jay_s_uk

Very strange on why its going back to home. I'm afraid I've not seen this happen on the CNC i've used with RRF. Maybe someone else can chip in?

droftarts

@MortenMod Are you confusing relative and absolute positioning? The G90 in your config.g sets 'Absolute coordinates'. So, assuming you are starting at Z110 after homing, you send G1 Z-30, it moves to position Z-30mm (or at least tries to, but it will generally stop at Z0). But it's moving from point Z110 to point Z-30, ie 140mm, not moving -30mm. If you sent G1 Z-30 again, it would not move, because it is already at Z-30. So when you send G1 Z5, it moves to Z5, which is 35mm away from Z=-30.

If you want G1 Z-30 to move down 30mm from it's current position (say Z110 after homing), you need to send G91 first, which switches to relative coordinates; ie if you send G91, G1 Z-30, G1 Z-30, it will move down 30 (to Z80), then another 30mm (to Z50).

(I'm not sure I've explained this very well, but hopefully you get the idea!)

Ian

MortenMod

@droftarts Aahhhhhh
Thanks a lot. It helped!