First layer help and advice on getting better than ok...
 
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First layer help and advice on getting better than ok...  

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Chris Mitchell
(@chris-mitchell)
New Member
First layer help and advice on getting better than ok...

I'm having a few first layer issues on my MK3S, especially after I did a little maintenance on it.  I've managed to get back to successful prints, but I'm becoming obsessive about getting a much better first layer. I am using a single layer print that prints 9 boxes along X and Y to help with bed leveling and also for reasoning over thinkness.

First, I have pictures of a using stock MK3s .15 settings with Prusa PLA (grey).  Since this is a 1 layer only print, it's .2 thick for first layer. Majority of boxes print pretty well, although I have 2 showed issues.  The center box (1,1) seems under extruded, while (0,2) upper left seems to have globs, suggesting head too close.  

For PETG, I've had massive problems with adhesion.  So I've used modified settings (first layer 85->90, first layer .2 -> .3, and first layer speed from 800 -> 500 mm/sec).  This has helped a ton and produced a relatively good good print.  Although in 0,0 I now see some 'waves'or ripples.  

I suspect I haven't nailed in the bed correction yet.  Are there other suggestions?  Again, I'm printable, but just trying to get even better.  

The current print takes nearly 90 minutes thanks to slower PETG first layer speed I've chosen...

Thanks!

Posted : 01/05/2019 10:27 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: First layer help and advice on getting better than ok...

hi Chris, 
are you using 3x3 mesh bed levelling or 7x7 mesh bed levelling?

the latest firmwear allows you to select 7x7 mesh bed levelling in the configuration menu, this gives more sample points and tends to lead to a better result. 

THEN...   work only on the centre of the bed, for Live Z!      
Jeff Jordan's

Life Adjust Z my way, is a threar with loads of information and sample gcode for PLA, PETG and ABS.

Link to Life Adjust Z My Way

Once you have the middle of the bed correct, change to adjusting Bed level Correction, to get the front, back, left and right sides correct...     if you need to adjust a corner, then adjust both adjacent edges, say front and right for the front right hand corner...   this should get you working well

rather than the  9 spot file, you might find a 200mm open square works quicker... see attachments. run the file for a couple of laps, stop the print,  and you should see which points need adjusting...   adjust them using bed level correction, in the configuration menu on the LCD. 
Cler the build plate, then re run the file, to see if you have improved matters...

 

like Live Z, going more negative, or less positive, reduces the gap between the extruder and the build plate, 
Similarly going less negative and more positive increases the gap between the buld plate and the extruder.

good luck,

regards Joan

So far I have never had to resort to the Nylock nut method...    of bed levelling. use search if you want to look into this...

Attachment removed

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 01/05/2019 10:48 pm
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(@)
Illustrious Member
RE: First layer help and advice on getting better than ok...

I did the full hard bed tweak, adding solid washers to adjust the nine points. And with all that effort to get the bed perfect, every time I measured I got different results.  Then I found this command:

M860 S35 ; wait for PINDA temp to stabilize

And my MK3 print world got better.  A little bit later found the 7x7 cal in a user built firmware, and literally haven't touched bed correction since.

Posted : 02/05/2019 12:23 am
Chris Mitchell
(@chris-mitchell)
New Member
Topic starter answered:
RE: First layer help and advice on getting better than ok...

Thank you so much Joan.  No, I had not been using 7x7, but 3x3.  Once I hunted that down things got better.  However, I just went ahead and did the nyloc nut leveling.  Now my level is within .06 across my bed.  I think I can do a bit better, but this is already MUCH better.  I'm making my first test print (like above) right now.  My first layer calibration print showed .19 to .20 consitently with digital calipers.  I'll let you know the outcome, but your pointers helped a lot!

Posted : 02/05/2019 6:23 pm
Chris Mitchell
(@chris-mitchell)
New Member
Topic starter answered:
RE: First layer help and advice on getting better than ok...

So, here is my bed level after all of this:

Recv: 0.15750 0.13333 0.14750 0.15917 0.17000 0.15667 0.14750
Recv: 0.15083 0.15167 0.14417 0.13750 0.16250 0.17833 0.14583
Recv: 0.15583 0.15250 0.14167 0.14854 0.15917 0.18500 0.15917
Recv: 0.15167 0.13917 0.15500 0.15583 0.16875 0.17833 0.15667
Recv: 0.16333 0.16500 0.18917 0.16854 0.18167 0.20167 0.15833
Recv: 0.17583 0.18333 0.18667 0.14750 0.17417 0.19750 0.15333
Recv: 0.14917 0.16583 0.17917 0.15500 0.20000 0.20417 0.15500

PLA at 225/55 showed an impressive print  This was a MK2 file (and temps).  Printing at 230/60 per MK3S required a small dial bit of dial in from there and got an equally good print (all be it with .22-.23 layer height on calipers) that got a little nudge of refinement.  

Thanks again for your help.

Posted : 02/05/2019 9:44 pm
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