Filament specific Z offset  

this thread was hijacked -- the question wasn't whether you should adjust Z

I don't need any advice on whether Z should be adjusted.  As was asked in the OP, I also want to adjust Z by the filament, not the printer.  I am having problems with PETG sticking too much and I hate scraping the bed.  I want my sheet to last a while.  I know from experience that Z adjustment affects how strongly a filament adheres to the bed and I have verified this by adjusting Z for PETG.

Is it possible to adjust Z based on the filament?  It is a pain to change Z offset on every print, which I do often.

Yes, earlier in thread. Other options might work with other firmware.

Posted by: @mchahn

[...] Is it possible to adjust Z based on the filament?  It is a pain to change Z offset on every print, which I do often.

Assuming you mean you want to do it in filament or other custom gcode, yes. This was discussed at some length early on in this thread. G92 can be used to set the current position to any height you like. Essentially, you tell the printer to use the actual height of 1.02mm as 1.0mm for example.

Adjusting Live-Z directly in gcode is not something I've seen done on a Prusa. On other boards, you might be able to use M290 to make such adjustments, but I haven't tried doing so on a Prusa. It's not listed as supported, so I would not expect success.

On stock Marlin, babystepping (roughly the same as Live-Z) can be phased out over successive layers after the first. Here again, I am not aware of this being done in the Prusa firmware.

Available gcode commands listed in firmware source code

Anybody interested can look through the Prusa source code here. There's a summary starting at line 4101. 

How to add gcode based on filament?

Thanks, but how do I add gcode based on the filament selected?  I'm hoping to be able to just select a filament and have the Z-axis adjusted accordingly.

Create a custom filament preset or master script

Posted by: @mchahn

Thanks, but how do I add gcode based on the filament selected?  I'm hoping to be able to just select a filament and have the Z-axis adjusted accordingly.

Ah, sorry. You need to insert the appropriate gcode commands somewhere. To make an adjustment for a specific filament, using the custom start gcode option under Filament Settings is a good place. Add the gcode and save your settings in a custom preset.

One challenge is that this is only for that one specific filament preset. You could instead write some custom gcode that you would use for every print to detect types of filament (e.g., PETG versus PLA) and put your adjustments there. This could go in your custom start gcode under Printer Settings. (All assuming you're using PrusaSlicer.) A series of if and elif gcode statements could be used to add as many "flavors"as you like. This takes a bit of thought and discipline as the "coding" options in most slicers are very limited.

Thanks Illustrious Member

I'm pretty sure you've given me what I need.  I should have noticed the g-code in filament settings.  It should work for me.

RE:

Posted by: @haevaristo

humm... sorry but I am not following it entirely... I currently have, e.g. -0.6 on my Z live adjust. If I want the print to go to -0.9 for a specific filament.

So I do:

G1 Z0.3 F500;
G92 Z1;

?

 

This is what .02 difference looks like. Ripples on the right, perfect on the left. Much more obvious in person, not the best of photos.

RE: Filament specific Z offset

@bobstro - helpful suggestions as always.

Definitely still would vote for being an adjustment in filament settings if devs ever decide to add that as an option.  I adjust daily by 0.02 or 0.01 for certain brands of PLA. As @anda showed the result on solid bottom infill of a 0.02 z height can be perfect vs waves.  When you sell cosmetic pieces that can be the difference between increasing amazon inventory by +1 vs increasing trash can inventory by +1.

Beyond being able to do filament specific z adjustments I personally would love the option to make first layer adjustments by FEATURE.  A -0.02 for perimeters, for example, or +0.02 for bottom infill.  The minus 0.02 on perimeters can make a huge difference when you have a custom name embedded on the bottom but are trying to avoid the "waves" on bottom infill.  Corners don't lift as much.  Would make for more consistent results for me.  Still would watch first layer but when you have 5 machines going and are easily distracted.......SQUIRREL......  can save the quality of a print now and then.

RE: Filament specific Z offset

I would have made a forum account if I hadn't gotten one already from Printables, just to add my opinion on this discussion: different filaments materials may need different Z-Offsets, this is why I personally need it to be in the filament tab.