Best practice for Z offset

[jaysenodell 18]

I'm turning to the community here to help me develop a solid set of habits. I'm still working out the basics with my setup:

• Ender 3 S1 Pro (2.0.8.28/1.0.8)
• Cura 5.6
• FreeCAD 0.21.1
• Inkscape 1.3.2
• OSX 14, Linux (varies), Windows 11

 

I've successfully managed to go from idea to usable PLA tool with, IMO, acceptable levels of waste and issues. Now I've torn everything apart, reset everything to factory defaults, and am starting from scratch in an effort to reduce the beginner's cruft in my configs and workflows. Which brings me to my hatred of Z offset and the Ender's inability to use continuity to detect proximity to the build plate. 

 

The S1 Pro auto level leaves about 3-4mm from the extruder nozzle to the plate. Fine. The Ender firmware has the ability to set a Z offset to account for this. But so does Cura. It seems to me that these Z offsets should not be seen as synonymous as I would need to update the Cura config and reslice all models every time I adust anything on the Ender.  It seems to me that Cura and the GCode should be ignorant of most hardware calibration making the GCode reusable over non-material changes. Exceptions being: filament change, nozzle diameter change, printer type change. 

 

Am I thinking about the "hardware vs software" configuration properly? 

 

Thank you in advance for keeping a NooB going in the right direction.

[GregValiant 1,351]

Natively, Cura does not use a Z-offset.  You can add one by enabling the "Z-Offset Plugin" from the Marketplace.

 

Cura always assumes that "0" means "0" because where the build plate actually is in space it is impossible to tell.  It's the users job to move the build plate into position so the "Z=0" (the bottom of the nozzle) exactly coincides with the top of the build plate.  People use the word "leveling" but that's a misnomer.  You are setting the "Initial Z" to zero.

I use a piece of parchment paper which means that if I had issues "adjusting the initial Z" then I could use the plugin to make an adjustment.  If you use ABL then the adjustment is the Z-offset setting in the printer and there is no need to adjust it in the gcode by using the plugin.  They are not "synonymous" but rather "mutually exclusive".  If you try to use both you'll end up chasing your tail.

 

[jaysenodell 18]

Thanks! I assumed I was seeing this incorrectly and that the hardware should manage the calibration of the build environment leaving Cura a "simple volume" of known dimensions in which to operate. I have been playing with subtractive manu (CNC gcode) a bit before additive and there have been enough "that isn't the same" hiccups that I wasn't sure about this one. 

 

Thanks again!

[Slashee_the_Cow 429]

3 hours ago, jaysenodell said:

Thanks! I assumed I was seeing this incorrectly and that the hardware should manage the calibration of the build environment leaving Cura a "simple volume" of known dimensions in which to operate

Some newer models (like the Ender-3 V3 SE) completely auto-calibrate the bed level and Z offset for you (there aren't even knobs to manually level the bed). The dimensions of the build volume come from a printer's definition file in Cura.

[rimbo 0]

What if one faces a case like mine - the bed is level to "piece of paper tight between the nozzle and the bed" yet printing always seems to start a whole layer too high?

[Slashee_the_Cow 429]

3 hours ago, rimbo said:

What if one faces a case like mine - the bed is level to "piece of paper tight between the nozzle and the bed" yet printing always seems to start a whole layer too high?

Did you also check that if you set the printer's position to Z0 that the nozzle is low enough?

[DivingDuck 105]

11 hours ago, rimbo said:

yet printing always seems to start a whole layer too high

This is the case @GregValiant described. My A4/80 g printing paper is around 0.1 mm thick. This is the offset you would like to compensate with a tool like Z-Offset.

Most people didn't compensate this that way back in the days and use a higher flow rate for the first layer instead.

[Slashee_the_Cow 429]

3 hours ago, DivingDuck said:

Most people didn't compensate this that way back in the days and use a higher flow rate for the first layer instead.

I hope (can't actually confirm, given the printer decided on it) my Z offset is right and I generally print a thicker first layer with wider lines and slightly higher flow just for adhesion reasons. If your Z offset is off enough it'll affect every layer (either by squishing into the filament as it prints - great recipe for a clogged nozzle - or by making it sort of drool down a bit instead of laying it down right under the nozzle).

  

3 hours ago, DivingDuck said:

My A4/80 g printing paper is around 0.1 mm thick. This is the offset you would like to compensate with a tool like Z-Offset.

Before I got the E3V3SE I usually used something a little thinner - a lot of receipt paper is about 0.08mm and I found that worked a bit better, at least in my case. And then because my OCD brain won't shut up about accuracy I actually bought a feeler gauge and used that to measure it.

Edited January 12 by Slashee_the_Cow