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Is there a specific name for that problem? What causes this, and is there a way how to solve it?

Printed with PLA, 2 mm nozzle diameter, 0.2 mm layer height, 20-60 mm/s, 200 °C extruder, 60 °C bed.

Top

Bottom

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  • $\begingroup$ Welcome to 3dPrinting.SE! What does the bed side look like? Is it as you'd expect? You state the print speed is 20-60mm/s ... It looks like to my untrained eye the travel speed is too fast. If the base is printing at 20mm/s and looks fine, then goes to 60mm/s after the base layer, you may need to slow the other-than-base-layer down to 40mm/s and see if it helps. $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Jul 6 '19 at 15:08
  • $\begingroup$ Bottom looks nice, pretty smooth (img attached). Will try to print non-first layers with slower speed. thx $\endgroup$ – user236012 Jul 6 '19 at 15:15
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    $\begingroup$ @PerryWebb - I'm not seeing that at all. The first layer is flat and smooth. How did you come to that conclusion? $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Jul 6 '19 at 18:24
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    $\begingroup$ That looks to me like overextrusion $\endgroup$ – Trish Jul 6 '19 at 19:12
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    $\begingroup$ A 2 mm nozzle diameter is quite large, what filament diameter are you using 1.75 mm or 2.85 mm filament? I expect this is a typo. $\endgroup$ – 0scar Jul 6 '19 at 20:45
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I have experienced this problem. This picture is one that I could have taken.

It has always been because I was putting too much plastic into the available space.

This has been caused two things: overextrusion -- squirting out too much plastic for the intended layer height, and the bed being too "high" so that the gap between the nozzle and the bed is too thin.

In both cases, too much plastic is trying to be placed in too small a volume. The plastic has to go somewhere, and ripples follow. Because the nozzle rubs against the adjacent lines which have already been deposited, an up-bump pushes up the nozzle on the line beside the bump, and a coherent pattern of ripples can form.

The "bump up" is a real effect from the elasticity of the Z-axis, including all the resulting strains of twisting and lifting the nozzle.

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  • $\begingroup$ @Oscar's thought about belts could be part of the problem. Measure the X-Y size of the object you printed and compare that with the design. Adjust the steps/mm for X and Y until that is right. If the object is printing too small, that would also create the "too much plastic in the volume" problem. $\endgroup$ – cmm Jul 11 '19 at 12:50
  • $\begingroup$ Thanks for the thorough explanation! I was looking for an explanation as I was having the same issues on my Ender 3. I lowered the bed just a little bit (thus increasing the distance between nozzle and bed) and the first test print comes out waaays better. $\endgroup$ – Andy Sep 30 at 9:59
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This could be a number of things, I personally think it could be either over extrusion or an issue with one of the belts. Depending on the printer, you may need to manually go in and adjust your steps per millimeter, which you should be able to find a guide on. If that doesn't work, then look into belt tension adjustment. Hope this is able to help! I like to use the Simplify3D Print Quality Guide for situations like this, it tends to be very useful.

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