Baby stepping lower than first layer height increases z height

Phaedrux

Firmware and DWC version?

moth4017

@Phaedrux
Duet Web Control 3.4.5
Board: Duet 3 Mini 5+ (Mini5plus)
Firmware: RepRapFirmware for Duet 3 Mini 5+ 3.4.5 (2022-11-30)
Duet WiFi Server Version: 1.27

Phaedrux

Does the print head actually move up, or is it just a display thing?

moth4017

@Phaedrux yes the gap between the nozzle and the bed
jumps up to the reported z height

moth4017

@Phaedrux do you want to move this thread to issues, as it seems a very consistent issue .

gloomyandy

@moth4017 How did you install 3.4.5? If you used the zip file you may want to resinstall and test things again. See: https://forum.duet3d.com/topic/30814/homing-issues-with-rrf-3-4-5-on-duet-3-mini

moth4017

@gloomyandy just reinstall the new file issue still there

layer height was 0.3 , baby stepped to -0.35 z height jumped to 0.35

files here https://forum.duet3d.com/topic/30696/homing-issues/5

moth4017

@gloomyandy @Phaedrux

just install 3.5beta1 (2022-12-23)

the issue with baby stepping still there.

on the first layer of a print if the nozzel needs to be moved closer to the bed ( using bed baby stepping "-" negative,) it will go negative until the negative value = the first layer height
e.g if layer height = 0.3mm and you baby step -0.3mm the nozzzel will go closer to the bed

as soon as the negative baby stepping layer is grater than the print height (ignoring the -) e.g baby step = -0.35 the layer height z valve will also go to 0.35 and if you go more negative on the baby stepping the layer height z valve will increase.

If you then "Pause" the print, and baby step "-" the nozzle will th
en start going closer to the bed again, layer height z valve not changing.

gloomyandy

@moth4017 What is your M208 lower limit set to for Z? I suspect it is 0. By requesting a babystep of -0.3mm (when the current Z position is 0.3) you are asking the system to move outside of those limits. If you really want to be able to move below Z=0 then you probably need to change the M208 settings (but be aware that if you change this limit it may impact the homing position) or use M564 to allow movement outside of the limits. Probably the best solution is to correct your probe offsets so you don't need such a large babystep (or any at all).

moth4017

@gloomyandy

Hi Andy, yes my M208 Z0 , i only found this out when i had changed my tool head which has a different Z offset , I just found it strange that the Z head was increasing once passed the offset should it have just stopped at Z0 , not then changed the direction of the baby stepping?

thanks for the reply