PETG Leaves Blobs While Printing...



  • ...with a CR-10 and Cura 4.8. Seems to print great but every once in a while, say 2 or 3 times during a 3 hour print, there will be this blob of material that appears randomly. Sometimes off the part and sometimes right in the middle creating all sorts of havoc. Any suggestions very welcome. Thank you



  • @lhawes You might have some PETG on your hotend where its not supposed to be and it heats and falls off. See if you have some filament between the heatsink and block or some around where the nozzle screws in - then you have a leak inside the hotend and it will get worse. You probably will either have to do a real good cleaning and reassembly job or replace it



  • @mpirringer said in PETG Leaves Blobs While Printing...:

    @lhawes You might have some PETG on your hotend where its not supposed to be and it heats and falls off. See if you have some filament between the heatsink and block or some around where the nozzle screws in - then you have a leak inside the hotend and it will get worse. You probably will either have to do a real good cleaning and reassembly job or replace it

    THANK YOU for the reply and I think I might have solved the problem with a little different approach. I checked all of the above and still had the problem. I didn't get a chance to watch each print because 'life' but it seems as though the blobs would occur early in the print, then settle down and print great later in the print.

    My theory was that the bed was just a little too high and was over extruding for the bed height leaving excess material around the hot end and pushing that built up material around until it reached the point where it had to drop off. It's printing now with a slightly lower bed height and a reduced first layer down to 85% and there's no perceptible build up. Life is going to happen again not allowing me to watch the entire print but it looks very good so far.

    I'll post after the print is done and report the outcome. Fingers crossed and either way I hope this might help someone else.



  • @lhawes On PETG compared to PLA you need to back off a bit on the first layer .



  • @mpirringer said in PETG Leaves Blobs While Printing...:

    @lhawes On PETG compared to PLA you need to back off a bit on the first layer .

    VERY helpful... and the print was a success. I've got the extrusion mult. down to 95% and may try just a little lower in future prints or even test to see how low I can go before the print fails.

    THANK YOU again for the response and happy printing...



  • @lhawes To dial in extrusion multiplier I use this

    https://grabcad.com/library/frc1989-filament-dial-in-1

    and Then measure with a caliper. The walls are 1, 1.25, 1.5, 2, 3mm respectively it also can show some slicing problems like if there are gaps and/or lets say the 1 mm is dead on but the 2mm one is way off. It has enabled us to tune the printers to a point where we can print stuff in HIPS (which we pick up for $10 or less / kg and get all the problems worked out and then print it in Taulman 910 and expect dimensional accuracy to the point. So I can print a planetary in a mix of HIPS. ABS, PETG and Nylon and expect it to mesh - not that I wanted to do that as a practical thing


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