Observations on print quality issues  

Observations on print quality issues

I am posting this in the MK4S area because that is the machine I am using – with a 0.4mm HS nozzle. I am posting it not so much that I want help but as a warning/information for others.

I was recently printing a model (a 3mm thick perforated disc) in PLA on a smooth PEI sheet and noticed that the top layer was quite rough in one area and promptly suspected that I was enjoying a bed adhesion issue, not that I could see evidence of the print separating from the sheet nor any first layer problems. My next move was to thoroughly clean the sheet and try again with exactly the same result down to the pattern of the roughness and area where it appeared. A change to a different spool of PLA at this stage made no difference. In order to pin down the problem I moved the model in slicer to another area of the sheet and printed it again and again the result was the same. Rotating the model in slicer produced the same result – the roughness was in the same area of the model irrespective of model position or orientation.

At this point I noted that the area in question was in a region where the was a lot of XY activity (short lines between two of the perforations on the disc) and closer inspection suggested that not enough material, rather than too much, was being deposited.

To cut a short story long I discovered that my problem was resolved by doing a couple of cold pulls, whereupon the problem was resolved. It would seem I had experienced a partial nozzle blockage and that the ‘Stuck filament detection’ option had failed to identify this. If there is a moral to this tale it is probably ‘don’t leap to conclusions about poor print issues and investigate them. Thoroughly.’

B