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Here is an extreme example of notches caused by the printer. They go along all sides but are the strongest on the Y faces. They also happen quite randomly sometimes they are tiny sometimes they are strong.

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I have tightened the belts already and while that reduced the ghosting on the X face a lot, it did nothing on the Y and actually never helped with the notches. This test cube has notches and ripples too but not that strong (the skirting on the bottom of that cube is my fault I set the bed level a little too low).

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All models have been sliced with Ultimaker Cura and printed on an Anet A8. Flow = 110 %, layer height of 0.1 mm for the first example and 0.2 mm for the cube, printing temperature = 195 °C, no change on jerking and acceleration from default settings. Cube size = 20x20x20 mm.

The printer has frame support https://www.thingiverse.com/thing:1672959 but no other upgrades yet.

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3 Answers 3

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I see two problems with your printer: your filament seems to overheat in some areas, and you overextrude a little. My suspicion is, that your heating behavior is not well tuned and it overshoots the target temperature, leading to an overcooked filament, then the temperature drops below the temperature you need, leading to a wavy pattern and brown lines.

fixing

I suggest running a PID-tune cycle to get better heating behavior and then recalibrating the printer's extruder.

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  • $\begingroup$ Does this happen with 195°C temperature too? I thought overcooking only happens on temperatures where PAL begins to boil which is beyond 210° Also I have underextrusion too sometimes. You can see it on the top of the Y frame, there is a deeper notch. Supportmaterial also often gets underextruded at the beginning of a layer line (I have retraction off btw for that reason). $\endgroup$
    – user6329530
    Commented Feb 23, 2019 at 18:26
  • $\begingroup$ @user6329530 no, but your thermistor is probably inconsistent, resulting in the temperature swaying between above 210 °C and below 190 °C most likely. $\endgroup$
    – Trish
    Commented Feb 23, 2019 at 20:07
  • $\begingroup$ OK I will monitor the temperature on that thing maybe that pid tune works $\endgroup$
    – user6329530
    Commented Feb 23, 2019 at 20:32
  • $\begingroup$ Also make sure the hotend cooling fan is functioning properly. $\endgroup$
    – Carl Witthoft
    Commented Feb 25, 2019 at 15:50
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I noticed that thermistors provided with Chinese kits are not up to specs. Do yourself a favor and go to mouser or digikey and order a proper thermistor that is rated for the temperature range in question.

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  • $\begingroup$ Hi, you make a good point, but we strongly urge answers to include a link to a part (or software, or whatever) which meets the requirements you propose. $\endgroup$
    – Carl Witthoft
    Commented Feb 25, 2019 at 15:49
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While you may very well be having temperature issues, I see two other issues:

First, I think the "notches" are z-wobble. Z-wobble is often caused by bent z-axis threaded rods.

I have a very similar Geeetech I3 printer. A lot of my z-wobble was cleaned up by removing the threaded rods and making them more straight. You can find videos to help you do that, just search for "threaded rod straightening".

The other thing I did was decouple the nut on the threaded rod from the x-carriage assembly, allowing it to float in the X-Y plane as it pushes the x-carriage up. The x-carriage ought to be guided up by the smooth rods/bearings. Unfortunately, if the nut is fixed to the x-carriage, the bent threaded rods are strong enough to over-power the smooth rods/bearings and make the whole assembly wobble.

The other problem I see is that your printer seems to be extruding too much filament. That is likely causing the little pyramid flair at the base of your print. If you tell the printer to extrude 100mm, it ought to extrude 100mm, not 110mm. Again, a search for "extruder calibration" will tell you how to do it. For me it involved extruding, measuring, a bit of math, adjusting some variables in Marlin, compiling and uploading the with Arduino IDE. Repeat until 100mm extrudes 100mm.

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    $\begingroup$ The resulting prints show more positional accuracy than Z-wobble, for Z-wobble it is too random and not in sync with pitch of the threads. But this can indeed cause a lot of problems for some 3D printers. $\endgroup$
    – 0scar ♦
    Commented Feb 25, 2019 at 7:26
  • $\begingroup$ @Oscar, I see what you're saying. It doesn't have the saw-tooth kind of thing, but there does appear to be a period of about 10 layers to the anomaly. If it does have anything to do with the threaded rods, it is easy to see by watching the rods while moving the z-axis 100mm. $\endgroup$
    – Barry Grumbine
    Commented Mar 7, 2019 at 0:57

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