Extrusion problems at seams

[justus2342]

Hi,
I have a extrusion problem with my big delta printer. It seems that the end or the start (or both) of an extrusion is problematic. My current print project are assortment-boxes for drawers.

My first approach was to align all seams, but it did not went well. At the seams, excess filament built up a blob of plastic. The print nozzes stumbled over this blob and my tower axes skipped steps, what resulted in a shifted XYZ-Positioning and I have to cancel the print.

At first I took a look in the curling-corners section of the Simlify 3D Print Quality Troubleshooting Guide. It said overheating might be the problem. Thus I reduced the nozzle temp from 230°C to 215°C and turned my nozzle fans to 100% from layer 3 on. At least all no-seam-Corners came out well now. They were a little curly before. How ever, the problem with the seam-edge persisted.

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Next approach was to randomly distribute the seams. Finally I did not have to cancel the print, but it came out really ugly.

Next I took a look at the Blobs and Zits section of the Simplify3D guide. It did not help, because it was all about retraction. As far as I can see my extrusion problems are not about retraction, at least the problematic seam-edge had none.

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I use:

Printer: Tevo little Monster with:

• duet2 board (running RRF 3.4.4)
• linear rails, magballarms
• duet smart effector
• dual drive flying extruder (20cm bowden tube)
• e3d volcano hot end with 0.4mm NozzleX

Filament: Prusament PLA Galaxy Black

Slicer: PrusaSlicer 2.5.0

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However. To me my problem seems more slicer-setting-related (or maybe hotend-related) than Duet- or RRF-related. There are many many tuning knobs in the slicer. I do not know where to start.

I hope this is a common error pattern and you could maybe give me a hint, what I could try to change.

[Phaedrux]

Post your config.g and slicer settings. It looks like you're dwelling too long at layer change.

Do you have retract on layer change enabled?

[justus2342]

I am afraid the usual thing happened when someone is asked to give full details on printer- and slicer-settings. I went thoroughly through my settings to make sure everything is consistent and reasonable. I reduced the printing speed from 90mm/s to 80 mm/s and I lowered the line width from 0.6mm to 0.45mm.

Now my extrusion problem is gone. My best guess is, that there was a back pressure problem, because of the high flow.

The result is not perfect, but I can absolutely work with it and do not have to cancel prints anymore. However, I am little afraid that this problem might come as soon as I raise the print speed. But for now I am good.

@Phaedrux Thank you for being my Rubber Duck.