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Over the last two days I have tried everything I could come up with to fix the following issues.

It all started with bad bed adhesion.(pic.1) Solutions for these problems are readily available, so I calibrated my Z-axis (did the whole wizard from start to finish again) and started a calibration print over the whole buildplate, getting an interesting result.(pic.2) As you can see some area's are squashed nicely whilst others come off directly.

I then started looking for alternative Z-levelling solutions and came across an alternative calibration file (link1), at first glance the results seemed allright, -0,8mm seem to provide the best results (pic.3) however notice the darkened area to the left (could be the high temp of this test? 225c?).

To validate the number I did a full print on -0,8 and this is where it gets weird, the result shows a non uniform transparancy (pic.4) the mechanical properties are also a lot less. I used my caliper to check the printer and all seems to be well within expected ranges. The bed is also flat, checked with a ruler for deformaties.

Printing with the first spool of Prusa fillament, do notice some changes in the Z-level calibration print, the edges now bend upwards, this is done with the same Gcode and spool as previous (pic.5).

Any advice on what to do next? Printing on 210c with fan off for the first layer, test square on 225c, all PLA. Cleaned the bed with Acetone (99% pure) before each attempt.

Picture 1: enter image description here Picture 2: enter image description here Picture 3: enter image description here Picture 4: enter image description here Picture 5: enter image description here

EDIT: So Mick mentioned cleaning the nozzle which helped with the inconsistent first layer. In the end it was me being unaware that Aceton doesn't help with grease, a thorough scrubbing of the buildplate with soap and really hot water helped.

enter image description here

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  • $\begingroup$ have you cleaned your PEI sheet with some alcohol recently? Fingerprints ruin the adhesion, alcohols or acetone remove them nicely. $\endgroup$ – Trish Mar 11 '19 at 23:53
  • $\begingroup$ Hi Trish! My problem seemed to have been two-folded, first being (as Mick below mentioned) a partially clogged extruder. The second part was grease. I believe that my adhesion problem started by fingerprints but worsened after I tried the glue stick. Cleaning the bed with Acetone did not help. Cause, and I did not know this, acetone apparently is quite ineffective on the wax-like layer created by the glue stick. So a scrubbing with boiling hot water and some dishwasher soap did wonders :) Thanks you! $\endgroup$ – Paul V Mar 13 '19 at 8:01
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If you repeat a test and the problem occurs in the same location, then you probably have a problem with your bed or build plate. However, picture 3 suggests to me that you may have a partially clogged nozzle. Manually extrude some filament. It should fall straight down. If it curls as it comes out of the nozzle, then you have a partial clog. Brass nozzles do wear out, so if you've put some hours on your printer, it might be a good idea to fit a new one.

Edit: I meant picture 3, not picture 4.

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    $\begingroup$ Hi Mick, I cleaned the nozzle after reading your comments. The result of the square is a lot better! What helped more was to clean the buildplate. I used Aceton and was unaware that it doesn't help to get the grease of the plate, after a thorough scrub the PLA is sticking like never before. Thank you for your comment! $\endgroup$ – Paul V Mar 13 '19 at 7:45
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The Prusa i3 is coated with a PEI sheet. PEI and other build plates stick to the build but don't like to be dirty. Fingerprints can build up and create an interference layer of fats that lessen the adhesion to a point the pieces spontaneously pop off.

A good cleaning is often needed. For PEI Isopropylic Alcohol is a fast cleaner, but if you can remove the build plate soap and water work too - but take care not to go too hot as PEI can get damaged. For BuildTak and similar, Acetone also can do the job.

When using Gluestick to create a deliberate destroyable adhesion layer (for filaments fusing with PEI that can result in chipping out chunks) clean the surface afterward with a little water. In the choice of gluestick, make sure you get a PVA based one.

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  • $\begingroup$ Thank you Trish, as mentioned above the gluestick was part of the problem. Biggest issue was that I thought aceton would be a miracle solutions against the greasy buildplate. Assuming it was all clean I kept trying to print on gluestick residue. The stick itself came with the Prusa I3MK3 so am assuming it is the suitable kind ;) Will refrain from using it again with PLA, cleaning from time to time should be enough. $\endgroup$ – Paul V Mar 14 '19 at 15:37

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