[Solved] Can this First Layer issue be fixed?  

RE: Can this First Layer issue be fixed?

Are you using 7x7 bed mesh leveling? If not, that could help. 

RE: Can this First Layer issue be fixed?

Thanks for the reply have you had this issue?

Is 7x7 mesh leveling a setting on the Mk3S...

(I have successfully passed the calibration test and have been printing successfully with the printer for over 4 years)

RE: Can this First Layer issue be fixed?

Yes I have had this issue and the 7x7 helped. 

RE: Can this First Layer issue be fixed?

I switched bed leveling settings from 3x3 to 7x7.

No change.

RE: Can this First Layer issue be fixed?

@r

If the 7X7 doesn't solve your problem, there is a slight chance your idler screw might need a turn or half turn.

Regards

Swiss_Cheese

RE: Can this First Layer issue be fixed?

Very very unlikely as the issue happens at specific areas of the bed.

Adjusting my Z height for first layer is always responsive… indicative of great idler tension.

RE:

@r

To me based solely on your images, it looks like the faster parts of the first layer fill are under extruding, this can be caused by temps to low, blocked nozzle, or faster feed though the hot end, if the temps are good then it's possible that the idler is allowing the filament to slip as it's not melting as efficiently, creating more back pressure, But I have never suffered from this problem, what do I know?

Good Luck

Swiss_Cheese

RE: Can this First Layer issue be fixed?

Some possibilities to try:

• The plate has oils or something on it over there that IPA doesn't clean.  Try cleaning with dish soap.
• What speed is your first layer going down at -- 100% or 75%?  Try 75%
• I can't tell from the picture... are the lines not squished out enough, or is there not enough material?  I calibrated my extruder a few weeks ago and it was a bit off, so I wasn't getting as much material as I should have.  That wouldn't explain the variation you're seeing, but you could be slightly under-extruding. 
• What happens if you up the temp 5 deg?
• What happens if you use live-z adjust when it's on that part of the print?  If you can correct it there, what happens to the formerly good part of the print?

RE: Can this First Layer issue be fixed?

None of the above relates to my issue.

Do your first layers have absolute uniformity? Could you upload a picture of your first layer with a lighter color PLA.

Thanks

RE:

It seems that way… once again what is consistent is left side of the bed gets more 

“ squish” so but much less on the areas where there is no squish. I may just have a warped heat bed that the Prusa firmware can’t compensate for.

Coupd you snap a pic of your first layer with a light PLA with a print wide across your bed… you may have the same issue and just never knew…. You will need a light colored PLA to see it.

RE:

Ugh.  It looks like I'm having the same problem, and it looks like about 025 differences in the bed height.

This is the first layer of the first full-bed print I've ever done.  Up until yesterday, my prints have been smaller, never covering more than about a 2x3 rectangle (using the squares on the pei plate for counting).  I did have one 3x5 project.  I've moved them around the bed, but always tried to keep them in the middle 2x3 set of squares.  That middle area is where I've always done my z-offset tuning.  I've restricted prints to that area because early on I had trouble with things too close to the edges.  I've always assumed it was uneven heat distribution, but this seems to indicate that's not the issue.

I originally made the full print of this yesterday.  I think I had z set to -750, which hadn't worked great but the next layer spanned the gaps and I could use the print.  When this repeat print of just the first layer started, the rim and perimeters weren't sticking, as you can see.  When it started filling (lower right corner), I started lowering z from -750 to -800.  It started tearing a bit so I raised it to -775 and that seemed to be ok.  As you can see, it got worse as it approached the center -- the center of the bed is clearly lower than the lower right.  Then as it heads from the center toward the upper left, it starts improving.  Looks like when it's correct for the center, it's off in the corners, and if it's correct in the center it will tear things up in the corners.  I've got 7x7 leveling on.  I don't know if it's possible to super-fine tune this somehow or not.  The tears at the edges are, I think, a result of the perimeters not being present.

RE: Can this First Layer issue be fixed?

100% solved! 

Always make sure you wipe with IPA (and optionally Distilled water after IPA wipe)... this wasn't my issue.

The issue was a bed leveling one.... Removing your bed sheet will undo the precision of the last calibration.

1. Re-run the XYZ calibration. (3x3 completely fine).

2. Get a good Z height with the live adjust .... It needs to be good enough for a stick and not perfect as you will be adjusting it next step.

Follow https://help.prusa3d.com/en/article/bed-level-correction_2267

Included in the link is first layer calibration model that will help with Bed Level Correction... A "pseudo bed tilt" settings.

Basically my issue was rear and right was lower hence my infill had gaps on first layer.

I've learnt now to try not to remove the bed sheet unless changing to the rough PEI one... Let the bed cool down to remove your print on following prints after this.

How consistent has your adjustment been?

I'm curious as to how consistent your bed has been since adjusting.  When I first adjusted mine, it came out perfect.  But on the next print the right side was up about 10 um; then another 5 um after that, and another 5 um on the third print.  As nearly as I could tell there was nothing between the PEI sheet and the heatbed, but I did remove the PEI sheet in between prints because what I was printing was only 1.5mm thick and covered the whole sheet; I couldn't get it up without taking the sheet off and bending it.