After 1.5 hours of printing quality degraded

Question

Testing my new Wanhao i3+. PLA plastic(Wanhao), basic normal quality settings in Cura (I guess 0.1 mm layer, 40 mm/s speed, 60c bed temp, 200c extruder temp). After 1.5 hours of printing quality degraded, it makes some loose structure.

Edit: After finish I noticed that problem exists only in layers where it cycles printing/no printing. There is no problem on layers where it print continuously.

What is the reason can be and how can I fix that?

If the problem occurs most when you are doing the most advance/retract cycles, the problem is likely with your advance/retract settings. — Davo, Jul 13 '17 at 12:27

score 3 · Answer 1 · answered Jul 17 '17 at 14:21

This is very likely under extrusion caused by your feeder pressing down too hard onto the filament. If the feeder presses the filament very hard it then gets squished a bit, this is not causing much issues when you're only feeding in one direction as the drive gear is still pulling on fresh filament and shoving the squished part down at a steady rate. BUT once you got retractions things get awful as the squished filament then gets retracted and fed again at the same pace but due to the elongation at a smaller rate of material causing underextrusion.

You can either trade it in to some overextrusion by adjusting the extra length on restart setting, retract a shorter piece of filament (like only retract half a mm or something) or loosen the feeder so it doesn't squish down on the filament as hard.

Decreasing the retraction helped me in a simular situation – edosoft Jun 11 '19 at 14:45 — edosoft, Jun 11 '19 at 14:45

score 3 · Answer 2 · answered Jul 20 '17 at 16:33

3

If the problem occurs most when you are doing the most advance/retract cycles, the problem is likely with your advance/retract settings.

Have you tried cutting each of them in half and executing the same gcode?

answered Jul 20 '17 at 16:33

Davo

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markshancock · Answer 3 · 2017-07-20T16:08:20.397

It definitely looks like under extrusion.

First thing I would check is the filament feeder to make sure it has a good grip in the filament.
After that I would do another print to see if the problem is repeatable.

If it doesn't repeat, it may have been

A temporarily clogged nozzle
The filament was undersized in that segment and the filament feeder lost its grip.
The extruder got to cold for some reason in that segment and the feeder couldn't push the material through the extruder fast enough.

If it does repeat:

Re-inspect the filament feeder
Try increasing the the extruder temp to say, 225.
Try turning off retraction to see if it is related to those settings.

After 1.5 hours of printing quality degraded

3 Answers3