M2 Extruder Motor Jumping

[ednisley]

The temperature setting on the prints that failed were set to 240°C as I intended and the nozzle was at the same temperature when I was manually extruding/retracting in the video.

Forgive my nitpicking, but I think you have two problems that don't interact, even though they have similar symptoms.

There's a difference between the setting and the actual temperature during extrusion. If the cable to the hot end has broken, for whatever reason, the extruder will cool during prints as the connection makes-and-breaks while the extruder moves along the X axis.

Worse, the fault will be intermittent and, of course, won't happen with the extruder parked over on the side during manual extrusion.

Does the actual hot end temperature remain constant at 240 °C during the failing prints?

25mm/s indicated by the parameter 'Vmax e' on the screen

That's an inch of filament moving into the extruder and two feet of thread squirting out of the nozzle every second, which qualifies as crazy fast in my book. Back that down to 4 mm/s and the skipping during manual extrusion will definitely Go Away.

In round numbers, the hot end consumes 3 mm of filament per second during normal printing, so 25 mm/s is way out of line.

FWIW, I tried manual extrusion at 25 mm/s = 1500 mm/min and promptly stripped the filament, although that's with PETG in a V4 hot end.

[PcS]

On my viki under prepare ,then movement you select a movement amount usually 1mm per click of rotary dial. Then select extruder and you can manually jog the extruder for priming filament change....I may be a little off from memory but I know I once tried a too fast speed and my extruder did the exact same thing . I print in the worst place a cold damp basement and have to constantly run a lot higher extruder Temps to compensate. Maybe you are just too cold....I have done pid auto tune on hot end and have always ran around 240 for pla to work nicely for me .

[insta]

ed, just to argue for the sake of arguing, the MG hotend will keep up with that ridiculous speed on PLA with a 0.66 nozzle. You just have to run PLA @ 230C, 0.5 layers, and like 150mm/sec print speeds.

also the prints will look like crap.

[ednisley]

PLA with a 0.66 nozzle ... @ 230C, 0.5 layers, and like 150mm/sec

Talk about printing with a firehose: back of the envelope says that hot end gulps filament at 24 mm/s...

The hot zone for the V4 is a bit over 20 mm long, so it must get the plastic up to extrusion temperature in less than one second.

Yeah, that's crazy fast!

[insta]

https://www.youtube.com/watch?v=BGJska4xnyw

Look at the gear on the Greg's, then realize that's 3mm filament. Thing is hauling

[katmeg]

If it just started, I'd actually say your filament is too humid, and the moisture is preventing a good melting of the plastic...I'd suggest baking your filament.

I will hold off on baking the filament for now, just because my parts are printing all the way through and I don't have an oven available. The printer is in a temperature/humidity controlled lab so I don't think moisture is the main cause of the problem.

Does the actual hot end temperature remain constant at 240 °C during the failing prints?

Yes, the hot end temperature does remain constant at 240°C during the prints according to the LCD output.

In round numbers, the hot end consumes 3 mm of filament per second during normal printing, so 25 mm/s is way out of line.

Setting the print speed to a lower value (10mm/s) did certainly help to solve my problem, but is it possible we are discussing two different parameters? MakerGear's performance specifications include the following:

Typical print speeds: 80 - 200mm/s
Typical travel rate: 100 - 250mm/s
Extruder extrusion speed (manual): 300mm/min. Actual speed varies based on the object print settings

The print speed agrees with the default values in S3D (~53mm/s) and Cura (20mm/s), while the extrusion speed is near your suggested value of 250mm/min. I am not sure how I can find out exactly what speed my printer is extruding at, but I don't think it's equal to the print speed I am setting in my slicing program.

For the record, my last print turned out super well after all my attempted fixes and with the print speed set to 10mm/s and flow compensation equal to 95% (all other parameters the default value in Cura). I'm going to reprint a couple times and gradually increase the speed to see what I can get away with.

Thanks again for the support!

[ednisley]

the hot end temperature does remain constant at 240°C during the prints

OK, that rules out some mechanical problems, which suggests something has changed in the slicer settings.

Other things to check:

• Measured filament diameter vs. slicer setting
• Manual thread width setting? Try auto for all widths
• Manual flow override? The default 100% should be OK

Basically, you're looking for a setting that doesn't make sense. Whether it was inadvertently set to a nonsensical value, came from a mysteriously damaged profile (I've had that happen), or was left over from a previous experiment, it's time for a line-by-line examination. I don't use S3D, but if you post the config file we can take a look at it.

Have you done the thinwall box calibration to set the Extrusion Multiplier? If the measured thinwall box wall matches the slicer thread width, then it's correct.

I am not sure how I can find out exactly what speed my printer is extruding at, but I don't think it's equal to the print speed I am setting in my slicing program.

The terminology doesn't help much.

• Print speed is the nozzle speed across the XY plane
• Travel speed is the fastest possible non-printing speed in the XY plane
• Extrusion speed is how fast the filament passes through the filament drive

In round numbers:

• Print speeds range from 15 mm/s (on the first layer of my objects with PETG) to 150 mm/s (PLA infill)
• Travel speeds top out around 300 mm/s, after careful attention to XY acceleration
• Extrusion speeds depend on the XY printing speed

You can set the extrusion speed for manual extrusion (with the nozzle parked), but it's not a free variable during printing: the extruder must consume only the amount of plastic required to produce the thread. You can figure the actual extrusion speed by working backwards from the thread volume and XY printing speed.

Assuming a 0.4 x 0.2 mm thread extruded at 50 mm/s with Extrusion Multiplier = 1.0, the nozzle emits 4.0 mm³/s on the object. A 1.70 mm diameter filament has 2.3 mm² cross-section area, so it moves into the hot end at 4.0/2.3 = 1.7 mm/s = 100 mm/min.

If you increase the printing speed, the extruder drive will turn faster, but you can't print much faster than 150 mm/s, no matter which printer you have. At that speed, the filament moves three times faster, which is 5.3 mm/s = 300 mm/min.

Hotrod printers may have faster speeds, but make sure you know the nozzle diameter, thread width, layer thickness, and print quality before leaping to any conclusions.

If you specify a larger thread cross section (width x thickness), it will require more plastic and the extrusion speed will go up, but not by all that much.

So, dial back the manual extrusion speed to something sensible and we can chew on the config file to figure out what's happening during printing...