Extruder Motor Skipping and Inconsistent Layers
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Looks like you've tried the likely suspects. The symptoms sound like an under-powered motor.
Maybe double check the motor current setting in your M906 command (the E parameter) It seems unusual to me that the extruder motor has higher current than the X,Y, and Z motors.
One thing you didn't mention (or I missed) is the extruder temperature setting. I'd recommend watching the temperature on the DWC while the failing extrusion is happening. It's possible the heater is not running enough to keep the filament melted after a short amount of extrusion.
Related to this is your M308 command for the thermistor. If the B value is wrong it might be reporting a temperature that's higher than it really is resulting in cold-ish extrusion.
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An off the wall thought - if the under extrusion is happening at a regular interval, could there be a rough spot or some other mechanical issue in the extruder? You said you replaced the motor but you said nothing about the mechanics that the motor connects to. 10 mm (or so) could very well be the circumference of one of the gears in the extruder.
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@jens55 I would say the under extrusions are happening at semi - regular intervals.
However, this same issue is happening across multiple extruder motors and multiple hotends. That is to say I've replaced the stock E3d v6 hotend that came with the machine with a brand new hotend of the same model. The entire hotend, from heatbreak, to thermistor, to nozzle. All of it. The issue still persists, so its not to do with the hotend unfortunately. But thanks for input.
EDIT: I misunderstood you, you're talking about the gear the extruder is connected to not the hotend, yea it could be possible something is up with that. I'll have to take it off the extruder motor and give it a real good look and cleaning.
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@mikeabuilder So I neglected to mention that when I replaced the hotend I had run a PID tune at the same time and input the M308 value it gave me when tuning was complete. Any chance the values it gave me were wrong? I like your theory that I could be extruding at a cooler temperature than reported on DWC, any ways I can go about testing that theory further?
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Are you using the E3D thermistor, or something else?
M308 S1 P"e0_temp" Y"thermistor" T100000 B4725 R4700This isn't correct for the E3D thermistor.
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@phaedrux I am using the E3D thermistor, Honestly I've been learning as I go with this duet board, I'm pretty new to tuning and tweaking a 3D printer and used the default given thermistor value from the firmware configuration tool. I absolutely could have entered incorrectly.
I am using a 30W E3D 12v thermistor, what would be the appropriate M308 Value to input for that given thermistor?
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Try this instead
M308 S1 P"e0temp" Y"thermistor" T100000 B4725 C7.06e-8 -
@Secretasianman7, I think Phaedrux has you on a good track, but the typical way to test a thermistor is to put it somewhere at a known temperature. The classic method is an ice bath and boiling water. This gives two points to test at a wide temperature separation. But you can also look at the temperature reported when the printer is just turned on and neither the bed or hot end heating has started. The reported temperatures should be the same.
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The jerk and acceleration settings for the extruder look pretty low to me. I don't think that's causing your problem, but it will lead to other problems.
Is the print cooling fan turning on during the print and cooling off the heater block or nozzle?
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@secretasianman7 Check if the filament is feeding from the spool easily.
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@mrehorstdmd Thanks! What kinds of jerk and acceleration settings should I be looking at entering instead? Very new to tuning and tweaking a 3D printer, so I'm very much learning as I go.
Both the hot-end cooling fan and part cooling fan are turning on during printing.
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@phaedrux Just tried the new thermistor M308 parameter, and ran another pid tune, still having the same issue. If I put my fingers on the filament as Its being fed, I can feel almost like a bump or a jolt every time it skips and doesn't lay down filament. Could it be something in my slicer profile? I'm using PrusaSlicer with the MK2S profile. I've attached a few pics to show what's happening.
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Does it extrude cleanly into free air if you just use DWC to heat the hotend and use the extrude buttons?
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@phaedrux Just tested, it does not extrude cleanly into air when extruding from DWC. Also, when extruding into air, as the motor skips, I can make it skip a bit less by pushing on the filament with my fingers, but that doesn't cure the problem entirely.
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Looking at the print sample, it looks like the gap between bed and nozzle is excessive. This can cause exactly the kind of horrible mess you see here. Of course the 'not extruding cleanly into air' also doesn't help.
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@jens55 Nozzle height could definitely do with an adjustment, but I'd like to see good extrusion first.
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@secretasianman7, yeah, the bit about the motor still skipping and skipping less if you push on the filament is a great big red flag.
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@jens55 Agreed. Feeling very perplexed about the root cause as I've changed out nozzles multiple times, and swapped out the entire hotend, thermistor, heater cartridge and stepper motor to no effect. Quite a strange problem...
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@secretasianman7 said in Extruder Motor Skipping and Inconsistent Layers:
Swapped extruder motors to test if bad stepper. Also changed from a 1amp stepper to 1.5amp stepper to test if underpowered stepper.
So you had the problem before you swapped the extruder motor as well?
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@phaedrux Yes. The perplexing nature of this problem is that it has persisted across multiple motors, drivers, nozzles and hotends. Also across multiple filaments, all PLA.
