Random Movements

I have a prusa i3 with marlin development 1.0.3 and I'm having an issue with random movements. I've attached some videos to show whats going on. Pretty standard setup, no special features implemented other than the auto bed level setup. Ive used Mattercontrol, Slic3r and simplify 3d to create gcodes for printing all with the same issue. It appears to be random, Nothing seems to be in the code that I can tell. Videos are only of it moving to the y max but thats all I was lucky enough to catch before I got mad and cancelled the print. It will only go to y max or x min. I was going to switch to the current version of Marlin but it keeps throwing back errors when i try to verify or upload with more than 1 extruder. I've downloaded the 1.1 RC that I'm setting up to try that as I'm thinking its a firmware issue due to the multiple gcode generators all have the same issue. Any thoughts? Its really driving my nuts and making my prints look like crap.

[youtu.be]

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Gcode file was too large so i had to separate into 2 files.

The release candidates are still too buggy for general use, I would instead go to older releases rather than newer in case of unexpected behavior.

Are those y moves in the gcode? I can't open the txt files, maybe it's my tablet. If it's in gcode I'd check the slicer gcode for layer changes etc for any code. maybe you've enabled wiping?

If the problem is regardless of slicer, maybe it's due to a weak usb cable, or baudrats is set too high or there's a groundloop. Use a differen outlet, psu or distribution block. Use usb cable with ferrite bead.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

I couldn't find anything in the gcode file and I'm fairly certain its not in there as I've run the same code twice and it didn't do these random moves as the same times. First run it did it 3 times within the first few layers and the second time it waited until it was 10-15 layers before it decided to piss me off. I've gone from the 1.0.3 dev version to 1.1 RC and its doing the same thing only it seemed to do it less. Using the same gcodes as before as well as new ones.

One thing is I am using the 12864 LCD with SD to control the machine without a computer. I haven't printed anything through the computer but I will be tomorrow when I get back to my lab. I did hear that the big LCDS can actually cause problems but I haven't found any definitive posts or more thorough explanations, just speculation on various posts. I do have a the smaller LCD I can swap the big lcd out for to test, however my enclosure has the layout for the big LCD cut into it and I'd rather now switch if I dont have to, hah.

I can produce random moves to one endstop and back every time I "want".
This behaviour is happening here if I manually slow doen the print speed through the override - like in S3D.
Small parts with short lines are usually no problem, but bigger parts with long infill lines will cause trouble.
I can set the overall print speed to 100mm/2, first layer to 40% and if I slow the print during the first infill more than 20%manually the thing get's it's own mind in terms of print moves.

@Downunder35m: I've never seen it do that with my printer. So if I understand correctly it's only doing random stuff if it's running really slow using the feedrate function? So 40% from 100mm/s2 is 40mm/s2, 20% of this is 8mm/s2? I think mine will just run really slow.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

Adjustment of speed doesnt change the presence of the random movements on my machine.

I'll try to explain it better.
Using S3D here.
If I set a print speed for the first layer that is about 50% lower than the normal speed AND during the print lower the speed even more manually - that is when it happens.
Only for the first layer, never after that, but I never slowed the print down that much after the first layer.
Mind you it only happens with long lines, so small object of let's say 5x5cm never get the problem here.

I tried to track it down and so far it seems to be communication problem.
I did see through a serial monitor that S3D tried to send new commands long before the current print move was done.
If that happens again or the printer does not confirm the start of this new line it goes haywire.

I just had this problem, and just solved it. It's noise getting into the SD card ribbon cables.

I put a ferrite ring around the both the ribbon cables (together), and the problem vanished.

Good idea, I'll order some and try that out.

I hooked the printer up to my laptop and it's been printing for about 25 mins with no random movements so I'm think it's gonna be either interference or that LCD. I really hope I don't have to find another autonomous printing option because I can't leave my laptop tethered to this thing. Anyone ever use that MKS TFT28?

I am having exactly same issue while printing from SD card.. If I print through USB it prints fine.

I'll report back when my ferrite magnets arrive. I bought 5 for around $7 on ebay.

Sitrep:
Threw a clamp on ferrite magnet on each line to the LCD and have made 3 models without any issue.

[www.ebay.com]