Defective z-axis or PID needs calibration?

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BBID
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Defective z-axis or PID needs calibration?

Post by BBID » Sat Jul 08, 2017 8:48 pm

IMG_1855.JPG
IMG_1856.JPG
Using a M2 Rev. E (completely stock)) w/ Hatchbox PLA (Silver) and eSUN PLA+ (Orange) to print 20mm calibration cubes 40-80mm/s @ 200-220C. I'm seeing these lines in the walls of my prints no matter the print speed or print temp. The pattern seems a little too consistent to be a z-axis defect, but I'm not sure. The other cause may be PID values that are off (not calibrated), which results in extrusion temps that vary more than 1-2C. I'm assuming Makergear has set these PID values in the firmware, and is not tuning each M2 at the factory. Either way, I'd be surprised if M2 users needed to run PID autotune with the stock hardware right off the bat. If I changed extruders, I could see that it would be much more likely that PID would be the culprit, but I'm using the stock V4 hot end.

Does anyone know how to figure out which issue is causing the lines?

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Tim
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Re: Defective z-axis or PID needs calibration?

Post by Tim » Wed Jul 12, 2017 1:17 pm

Try changing the layer height to see if it's related to the Z-stepper.

BBID
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Re: Defective z-axis or PID needs calibration?

Post by BBID » Sat Jul 15, 2017 6:43 am

PID Tuning Results.jpg
So, I did exactly that. I re-ran the calibration cube print at 0.100 mm layer height and the results seemed to confirm a PID tuning issue. I then re-ran the calibration cube print at 0.200 mm layer height after running PID autotune on BOTH the extruder and the bed. I confirmed the PID values had been changed successfully after an M301/M304/M500 command by restarting the M2 and checking the new PID values were in place via the attached LCD. The PID tuning did absolutely NOTHING to fix this problem. I've already notified Makergear Support about this issue, but they've yet to give me any options to resolve this. I was hoping some of the forum members have ran into this issue before with their M2 and could give some advice....

Note: I did run the PID autotune with the bed cooling fan OFF, which may explain why the lines still show up when actively printing PLA with the fan ON. I'm guessing this may be the issue since the PID autotune isn't running under exact printing conditions???

BBID
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Re: Defective z-axis or PID needs calibration?

Post by BBID » Sat Jul 15, 2017 10:57 pm

PostPIDFanOFF.jpg
I suspected the cooling fan blowing on the hot end may be causing the temperature to fluctuate, so I did another test with the bed cooling fan off. To my surprise, the lines are still there and there is some obvious warping from a lack of cooling!!! Not really the print quality I was expecting from the M2. My Flashforge Creator Pro could print 20mm cal. cubes at 80mm/s with no warping or lines in the walls, albeit with a little more ringing, but that was to be expected with the smooth rods the printer was using. Super disappointed....I'll post back if Makergear offers a resolution.

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zemlin
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Re: Defective z-axis or PID needs calibration?

Post by zemlin » Sun Jul 16, 2017 8:03 pm

I have heard of waves on an M2 caused by inadequate pressure on the extruder drive roller. Might try snugging that up a bit to see if that makes any difference.

BBID
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Re: Defective z-axis or PID needs calibration?

Post by BBID » Sun Jul 16, 2017 11:06 pm

Infill Comparison.jpg
Filament tension (I'm assuming that's what you meant by filament drive roller) is actually the first thing I checked on my M2 when it arrived. I went so far as to retract the filament from the drive and put it under a microscope to measure the amount of "bite" the drive gear made in the filament. According to the guide floating around here on the forums, the filament tension was set perfect from the factory. I also tried changing the infill percentage and infill type, which also did nothing...the lines were still there.

I did notice however, whilst calibrating my extrusion multiplier, that when I print a calibration cube with 0% infill, no top or bottom layers, and only 1 perimeter, the lines finally go away (see photo). I have no idea what to make of this. THAT is how I expect walls to look...nice and smooth. Any other ideas on whats causing the lines?

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zemlin
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Re: Defective z-axis or PID needs calibration?

Post by zemlin » Sun Jul 16, 2017 11:36 pm

What are your infill settings?

BBID
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Re: Defective z-axis or PID needs calibration?

Post by BBID » Sun Jul 16, 2017 11:42 pm

What are your infill settings?
I'm using 20% rectilinear infill for the calibration cubes, all printed in PLA.

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zemlin
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Re: Defective z-axis or PID needs calibration?

Post by zemlin » Mon Jul 17, 2017 3:02 am

Looking at one of my parts and it exhibits similar waving. There were two parts in this build. A short, large part, and a taller, small part. The waviness only appears after the large part finished building and the printer was working only on the small part.

Try a build with 3 or 4 of your cubes on the build place at once. The larger parts I build are nice and even except for slight, random ribs which I attribute to filament diameter variation.

BBID
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Re: Defective z-axis or PID needs calibration?

Post by BBID » Tue Jul 18, 2017 12:22 am

No lines.jpg
Lines.jpg
I re-printed the same cube again, this time in Makergear PLA. The issue still shows up in the cube with infill. I sent Makergear the g-code I was using and they can't replicate the issue. The cubes need to be illuminated from the right angle to see the lines (see photos). I'm in the process of printing four cubes at once to see if the issue still shows up. Correct me if I'm wrong, but this really is looking like a PID controller issue. If the z-axis rod(s) were defective, we would see the issue in the perimeter-only prints as well, yes? If it is the PID controller, I'm not sure what to do about it, short of running autotune again...
Looking at one of my parts and it exhibits similar waving.
Zemlin, any chance you could post photos of the waving you are seeing? I can post my g-code here in case anyone wants to give this a try on their printer.

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