Extruder Motor Skipping and Inconsistent Layers
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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.
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Extruder tension problem?
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@phaedrux tried extruder tension in between all levels from very tight to minimal tension. Problem persists
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@phaedrux I'm running firmware version 3.4, any chance that either rolling back to a previous version or trying out 3.4.1 would affect things at all?
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Try disabling the print cooling fan in the slicer and see if the problem persists.
I'm using extruder acceleration of 3000 mm/sec, and extruder jerk speed of 50 mm/sec. You don't want either set too low because if the extruder can't keep up with the printing speed, the controller will limit the printing speed to values that the extruder can keep up with.
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It still seems like your temperatures are out of whack. Can you try increasing the temperature by 5 degrees at a time and testing the extrusion into free air? Keep upping the temp if it still isn't smooth. Stop after 50c or so if it still hasn't improved. The theory is that the hotend isn't actually as hot as it is reporting, so you're not actually melting the filament completely.
Also, how fast are you extruding when you test into free air? Is a slow 1mm/s smoother than a fast 5mm/s?
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@phaedrux Ok we're getting somewhere. I did as you asked, taking note of how much skipping occurred per each set temperature, from 205 to 250, as I extruded into the air. At 205 skipping was constant. Frequency of skipping began to reduce as temperature increased. At 250, skipping occurred noticeably less frequently than at any temperature below that. Though the skipping did still occur enough to mess up any print I would have done.
Also regarding feedrate, yes there is significant difference in skipping with feedrate. 1mm/s provides the least skipping, 2mm/s skipping is very much worse where extrusion barely happens at all, and at 5mm/s motor just vibrates in place with no rotation.
