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I have Prusa i3 derivative with MK8 extruder and Marlin 1.1RC8 as firmware. I already reduced the default speeds as well as the accelerations. But sometimes when trying to print with BQ PLA filament (220°C), mostly during filling areas, my extruder clicks. The below screenshot of Slic3rs Layers view shows the clicking "lines".

enter image description here

What settings I need to change to avoid the overextrusion in this case?

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    $\begingroup$ Are you sure it clicks exactly when retracting? Clicking mostly indicates extruder is unable to advance filament. In your case if it sounds when more filament is required (like filling areas), then you may try to reduce printing speed in such areas or increase nozzle temperature. $\endgroup$ – Mikhail Z Dec 13 '16 at 15:11
  • $\begingroup$ You are right. On a different object it becomes obvious that the clicking occurs when performing solid infill, even on a long "line". I'm using Slic3rs default values for the speed, so 20mm/s for solid infill (normal infill 50mm/s). $\endgroup$ – Thomas S. Dec 14 '16 at 19:33
  • $\begingroup$ If reducing speed won't help, then there is something else blocking smooth filament extrusion. With PLA you are most likely using cooler. Try reducing cooler speed for areas with 100% infill. Otherwise look at @rwinscot answer. $\endgroup$ – Mikhail Z Dec 14 '16 at 21:46
  • $\begingroup$ First 220c for PLA? You must be running at record speeds! But really a video would be a lot of help :-) $\endgroup$ – StarWind0 Dec 14 '16 at 22:41
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    $\begingroup$ @ThomasS, will the print continue fine afterwards? If it does, this may simply be the issue of a too large nozzle trying to squeeze infill into a gap smaller than itself - something many slicers struggle to handle elegantly. $\endgroup$ – Tormod Haugene Dec 16 '16 at 7:52
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Extruder 'clicking' is an audible indicator that the teeth on the hobbed gear are slipping... determining if this is a symptom or a problem is where things get tricky.

Not so sure about adjusting feed rate - as this will impact the entire print and may introduce other problems. Measuring the dimensions of a sample print with a set of calipers is a good way of identifying over/under extrusion.

General maintenance items perhaps?

  • Thermistor: Nozzle temperature measurement is dependent upon the precision of the thermistor and how well it is attached... 5% drift at 220 degrees may be as low as 210 degrees or as high as 230 degrees. Use a thermocouple on a multimeter, non-contact probe, etc. to verify your nozzle temperature.

  • Temperature: Nozzle temperature 'sag' of +/- 5 degrees is normal. Monitor nozzle temperature during a print to see if it stays within this range (see: Speed below).

  • Speed: Printing fast is awesome... when you have a hotend that can keep-up with the demands of melting incoming filament. Too fast, and the filament may not be properly melted; increasing the pressure needed to force it through the nozzle. Support material and infill typically print faster than the rest of the model - you mentioned hearing clicks "...mostly during filling areas."

  • Alignment: Make sure the hobbed gear, idler bearing, and filament are properly aligned. Filament that wanders around in the feed path is much more likely to slip and/or buckle.

  • Teeth: Make sure that the teeth of the hobbed gear are clean and clear of debris. 'Gunk' in hobbed gear teeth reduce grip on the filament.

  • Tension: Increase the tension between the hobbed gear and idler bearing if possible; worn hobbed gears may need a little extra help holding-on to the filament.

  • Stepper: Heat generated by the stepper motor can be passed down to the hobbed gear... softening the filament and causing it to slip. Stepper quality, capacity, and duty cycle can greatly effect how much heat is generated; 200+ degrees is entirely possible. Passive cooling (heatsink) is a good idea, active cooling (fan) is better.

A loose heat-break, nicks in the filament path, variations in filament width, etc. are all possibilities as well.

Also, Simplify3D created a great reference for solutions to common 3D printing problems (if you haven't seen it already).

https://www.simplify3d.com/support/print-quality-troubleshooting/

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    $\begingroup$ In my experience, the "clicking" isn't the gear slipping on the filament, it is the stepper motor not having enough torque to drive the filament. This is often caused by there not being enough space for the plastic to flow. Eventually something gives. Sometimes it is that the head is pushed away, but often it is that the stepper motor breaks torque, and jumps backward to the same driving phase position. $\endgroup$ – cmm Sep 18 '17 at 3:51
  • $\begingroup$ This is a very generic answer that is not specifically addressing the problem. Tormod and Davo are on the right track. The nozzle tries to squeeze in a line of infill in between two tightly placed perimeters, this causes extra friction as the molten filament does not fit in the left over space, hence the skipping. $\endgroup$ – 0scar Feb 25 at 22:17
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Try reducing to just two perimeters, and let that blue area be calculated as infill. This may give you a zig-zag infill instead of a straight, oversized bead.

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I've tried to reduce the "Extrusion multiplier" from 1 to 0.95, but that caused gaps. Now I've minimized the clicking by setting the Slic3r option "Infill before perimeters" on the "Print Settings > Infill" page.

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    $\begingroup$ PS: If the same amount of plastic still gets extruded - just in a different order - won't all parts will grow slightly in size? Also, I suspect that perimeters usually are printed first in order to get a smoother finish. Is this according to your experience? Thanks for sharing your answer. :-) $\endgroup$ – Tormod Haugene Jan 6 '17 at 10:16
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    $\begingroup$ Yes, I think, that the objects will slightly wider. I don't know why usually the perimeters are printed first - can't say they look worse now. $\endgroup$ – Thomas S. Jan 6 '17 at 15:06
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    $\begingroup$ so, here is my theory: There is the slic3r setting "Combine Infill every: X layers". What this will do if it's set to 3 for example is first print three regular sized layers of perimeters, and after that print one fat infill layer that is 3 times the layer height (that's a speed optimization). Of course this is more filament that must be pressed through the nozzle and may cause clicking. However, if you FIRST print the infill, then this optimization cannot be performed (so infill will always be printed at the set layer height rather than at a multpile of it) $\endgroup$ – user1282931 May 21 at 12:48
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One trap I've seen that causes the extruder to click, and over or underextrude is that the extruder control is in the wrong mode.

The extruder can be set into relative or absolute mode. If absolute extrusion values are sent while in relative mode, then the system will be trying to push more through than the nozzle or hot end can handle. You'll get blobs, clicking, ooze and it will damage the extruder and hot end.

Have a look at the G-code - and see what the "E" numbers look like - it they look relative (the same or close numbers repeatedly) or absolute (numbers slowly incrementing). Cura defaults to absolute - but initially was NOT sending the G-code to put my controller into absolute extruder positioning.

Note also - this is separate from the XYZ absolute/relative positioning modes.

  • M82 will put the extruder in absolute mode.
  • M83 will put it back into relative mode.
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The only time that I've observed clicking from the extruder on my Anet-A8 is on the first layers when I have the head height set too low - the nozzle is unable to extrude at a high enough rate to allow the filament to progress as requested.

If you have a somewhat repeatable scenario, you could try reducing the filament feed rate to 90% or so, and see what effect that has. I have already observed with one of my reels of filament that 90% feed rate gives me a less over-filled solid area, so maybe the default feed rates are a little on the high side (or this filament is of excessive diameter).

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I had this issue and it turned out to be the extruder cog rubbing on the inside of the hole in the heatsink, causing the stepper to slip.

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