Procedures for Setting Nozzle Gap for RepRap Firmware vs Marlin?

simonboydfoley

Just a quick one .... making sure I don't need to change my calibration techniques;

In Marlin with ABL I used to set my Z Axis offset initially calibrating at Z=0, (Nozzle on the bed) and and then reduce the actual Nozzle gap when the sensor was triggered (Absolute Z Offset) depending on my layer height.

I would set the Nozzle gap to be 80% of my layer height i'm printing at

Can I still do this with RepRap firmware ?
Is it like Marlin and does not attempt to auto account for your layer height ?

These are the settings i currently have on Config.h and I just un-comment the section relevant for the layer height i'm printing at

;G31 X-40 Y-10 Z0 P25 I1 ; Set Probe Offset and Z height to 0 ready for calibration
;G31 X-40 Y-10 Z0.809 P25 I1 ; Set Probe Offset and height for z = actual nozzle gap (so 0 nozzle gap?)
;G31 X-40 Y-10 Z0.629 P25 I1 ; Set Probe Offset and height for z = nozzle gap (0.18mm) for a layer height of 0.2mm
;G31 X-40 Y-10 Z0.689 P25 I1 ; Set Probe Offset and height for z = nozzle gap (0.12mm) for a layer height of 0.15mm
;G31 X-40 Y-10 Z0.729 P25 I1 ; Set Probe Offset and height for z = nozzle gap (0.08mm) for a layer height of 0.1mm

dc42

If you want to set the height at which the first layer is printed deliberately lower than the layer height, IMO that is best done in your slicer configuration. However, if you want to do it in firmware, then you need only increase the G31 Z parameter, as you have done.

simonboydfoley

Thanks @dc42 for confirming

yes sorry, I was not that clear .... I set the default in the firmware (I print at 0.2mm @ 110 C bed temp 99% of times) and then I override in the slicer

dc42

The G31 Z parameter should be set so that Z=0 corresponds to the nozzle just touching the bed or just gripping a sheet of thin paper. This does not depend on the layer height you want to print at. When your slicer wants to start a print with a first layer height of 0.2mm, it will send G1 Z0.2 at the start, before it starts extruding. If you actually want the nozzle to be at only 80% of 0.2mm at that point, that can be configured in the slicer.