Is Z offset limited?  

Re: Is Z offset limited?

First, a statement... I have no access to a powder coated build plate!, so no direct experience...

if I understand you correctly,

you are setting Live Z over a steel sheet, an adhesive sheet and a PEI sheet... which are the components of a sticker smooth sheet. and your results are satisfactory

you are then trying to correct the settings to work with a powder coated build plate which comprises a steel sheet and a layer of paint.

the Pinda probe senses the distance to the surface of the metal, It has no knowledge of the composition of any surface covering. you then run a live Z test and decide what offset to use from the original Pinda sense level...

if you set the live Z using the sticker sheet, I believe the nozzle will be correspondingly too high on the powder coated steel sheet.

if you try to use Gcode to instruct the printer to go lower, it will probably refuse...

so why don't you set Live Z on the powder coated build plate , and use G code to move the nozzle away from the build plate, for the sticker build plate?

that way the printer will not object!

regards Joan

Re: Is Z offset limited?

Hi and thanks for your response.
You are right, I just measured the textured and the smooth sheets, they are respectively about 0.75 and 1.15 mm
And your solution is just as easy as it could be! I will follow your advice.

I am still courious about why I can't set first layer to .25 and successfully add a Z offset in slic3r of -0.15. The printer, even if gcode tell it to, does not go to 0.10 but stays at 0.15.... (also tried to set first layer to 0.2 and add -0.10 offset with same results) Just wondering..

Thanks again Joan!

Just as a precisation... inductive distance sensors are affected by material thickness.

Re: Is Z offset limited?

Hi. I need some help to get a first layer.
I calibrated my mk3 with a smooth pei sheet, live adjust turned out 0.9 with PLA, prints are fine. Moved to PETG, first layer set to .25 and added a Z offset in slicer of .01 , prints are fine.
Changed the sheet to textured, first layer was way to high. I believe this is because the inductive pinda works differently on that. So I tried to add more Z offset, about 0.15 from my 0.25 first layer with PETG.
Now the printer in theory should go to 0.10 but it does not. Adding even more Z offset does not work either, the printer prints the first layer at 0.15 (or higher) no matter how much Z offset I add. I checked the gcode and looks fine.
How should I do?
How do you guys move from smooth sheet to textured sheet without recalibrating?

If I understand correctly, you want to create the G-code in the slicer and you could use both sheets without changing live from the correction.

It is impossible.

Calibrate both sheets, create print and refine live Z.

Example: PEI = live Z -0.25mm
            TEXT = live Z -0.6mm

When you know that you are printing on a PEI, the setting of the printer is set to live Z, there is changed to -0.25 and you are printing.
And when you print on TEXT, you set the live Z to -0.6 and you are printing.

I'm sorry for my english.

Re: Is Z offset limited?

Hi. I need some help to get a first layer.
I calibrated my mk3 with a smooth pei sheet, live adjust turned out 0.9 with PLA, prints are fine. Moved to PETG, first layer set to .25 and added a Z offset in slicer of .01 , prints are fine.
Changed the sheet to textured, first layer was way to high. I believe this is because the inductive pinda works differently on that. So I tried to add more Z offset, about 0.15 from my 0.25 first layer with PETG.
Now the printer in theory should go to 0.10 but it does not. Adding even more Z offset does not work either, the printer prints the first layer at 0.15 (or higher) no matter how much Z offset I add. I checked the gcode and looks fine.
How should I do?
How do you guys move from smooth sheet to textured sheet without recalibrating?

If I understand correctly, you want to create the G-code in the slicer and you could use both sheets without changing live from the correction.

It is impossible.

Calibrate both sheets, create print and refine live Z.

Example: PEI = live Z -0.25mm
            TEXT = live Z -0.6mm

When you know that you are printing on a PEI, the setting of the printer is set to live Z, there is changed to -0.25 and you are printing.
And when you print on TEXT, you set the live Z to -0.6 and you are printing.

I'm sorry for my english.

This is also a solution. But like Joan said is definitely possible. And also creating gcode for both cases, is quite easy, just add another printer profile and add Z offset. It didn't work before because probably I was hitting some firmware soft limit, but doing calibration on the lower sheet and raising with offset should be definitely possible. I don't know why but I don't really like fiddling with the live adjust more than is necessary.

Re: Is Z offset limited?

[...] I don't know why but I don't really like fiddling with the live adjust more Than is necessary.
I find it necessary on every nozzle change, and possibly when changing filament, so I'm doing it almost daily. I've got pre-generated "life adjust" squares saved off in a folder in my SD card, so the entire process takes minutes.

If swapping sheets, rather than generate gcode that only works with a certain sheet, I'll just dial in the measured difference after changing.

Re: Is Z offset limited?

[/quote]I find it necessary on every nozzle change, and possibly when changing filament, so I'm doing it almost daily. I've got pre-generated "life adjust" squares saved off in a folder in my SD card, so the entire process takes minutes.

If swapping sheets, rather than generate gcode that only works with a certain sheet, I'll just dial in the measured difference after changing.
[/quote]

How does that sd thing work? Is a setting you select saved in the sd or is just a filename you look at?

Re: Is Z offset limited?

[...] How does that sd thing work? Is a setting you select saved in the sd or is just a filename you look at?
Nothing magical. After finally appreciating how useful the "life adjust" procedure is in quickly calibrating Live-Z adjustments, I duplicated the same approach for a wider variety of nozzle sizes and materials. Right now, I've got top-level directories for different filaments:

Under each of these, I've got subdirectories for each of the 9 common nozzle sizes:

Under each nozzle directory, I've got a half-dozen or so calibration prints, including:

I've got a smattering of Linear Advance test prints as well. My process when swapping nozzles or beds is as follows:

Rather than spend the time to create each of these by hand, I've got Slic3rPE scripted so I can launch the build with a single command. Generating the 200+ prints takes about a minute. I then just sync them from my desktop to the SD card on insertion.

I've got PLA samples for various nozzle sizes available here. Let me know if you could use anything different.

Re: Is Z offset limited?

[...] How does that sd thing work? Is a setting you select saved in the sd or is just a filename you look at?
Nothing magical. After finally appreciating how useful the "life adjust"

I've got PLA samples for various nozzle sizes available here. Let me know if you could use anything different.

Wow! It looks Like the best practice...
I only print with .4 mm nozzle and PETG for now. I am also interested in printing with polycarbonate and nylon, but for now only PETG
Since it only is one nozzle and one material but two sheets, I also made a calibration square... 50x50, is certainly not as good as your way of calibrating though.

One question, if I may.

The first layer of PETG done with the calibration square or even a print, often leaves too much space between the solid infill and the perimeters. The measured height looks ok in the perimeters and a little extra height on the infill (a little overextruding possibly, which is fine for me. I increased in slic3r the perimeter to infill bond to 28% but still sometimes this happens. Also, is not on all 4 sides of the calibration square but mostly on two coincident sides... any idea?

To resume..
My speed an acceleration are low for first layer (10 and 300).
Extrusion height measured is .26mm vs .25mm settled (good enough..?)
Adhesion is good, overextruding a little, but infill does not touch perimeters on two coincident sides of calibration square....

Re: Is Z offset limited?

[...] The measured height looks ok in the perimeters and a little extra height on the infill (a little overextruding possibly, which is fine for me. I increased in slic3r the perimeter to infill bond to 28% but still sometimes this happens. Also, is not on all 4 sides of the calibration square but mostly on two coincident sides... any idea?Not sure on that. I have Print Settings->Advanced->Overlap->Infill/perimeters overlap set to 25%. If you've got it set to 28%, you're already doing more than I am. You could bump it up to see if it helps. It sounds like this is only a problem with PETG, correct?

Adhesion is good, overextruding a little, but infill does not touch perimeters on two coincident sides of calibration square....
You are using rectilinear infill pattern, correct?