Spontaneous X Y shift mid print  

RE: Spontaneous X Y shift mid print

Hi,
this can be caused by a variety of things. The most likely is the nozzle hitting the objects. Maybe something in this thread will solve it:
https://forum.prusa3d.com/forum/prusa-core-one-how-do-i-print-this-printing-help/glitch-in-the-matrix-how-did-this-happen/

...and in turn the commonest cause is poor adhesion - we usually ask to see the underside of a failed print to check.

...the commonest causes of which are:

   A dirty print sheet, look up threads about cleaning.

   and warping, often due to drafts or a low ambient temperature causing thermal contraction.

Cheerio,

RE: Spontaneous X Y shift mid print

Hello

I too am experiencing the same problem. running the same file from the machine several times the problem seems to occur at random Z heights. belts tuned, no obstructions felt when sliding the XY gantry. First layer adhesion is also good. Very frustrating.

Show us the underside of a failed print.

Cheerio,

RE: Spontaneous X Y shift mid print

This is absolutely not a loss of bed adhesion.

Reasons:

-All the parts were still stuck to the bed when the print finished.

-All six parts had the exact same offset even though they are physically separated from each other. (If this had been a loss of adhesion, they would not have moved the exact same amount) You can see this clearly in my original photo.

-I cleaned the build plate right before I printed these parts. The settings that I use consistently result in good bed adhesion.

Since you asked for it, I'm including a photo of the bottoms of the prints.

The parts did not warp and they were printed with a brim.

RE: Spontaneous X Y shift mid print

here is what i am getting with my prints.

Not wishing to hijack the thread, just trying to help resolve the issue.

Nick

RE:

Can you two zip & attach your 3mf projects, so we can see the settings and G-code?

I only had layer shifts, when using "Avoid crossing perimeters", which leads to two things: 1. A massive amount of extra commands for tiny movements, which can overload the processor and 2. Direction changes at full travel speed, without slowing down.

I'm not sure which caused my layer shift, but it sounded pretty brutal.. 

The other most common issue is the nozzle hitting the object. "Steeper ramp before obstacles" should solve this. Without it, the nozzle only lifts on a 1° ramp. If you have the tiniest warping on an edge nearby, the nozzle will crash into it at already pretty high speeds.

RE: Spontaneous X Y shift mid print

XY Troubleshooting

Requested files attached*

*The G code file is the exact original, pulled off the flash drive, that I used for the ill fated print.

*The 3mf file is not the original, I did not save the workspace when I sliced the models. I have included a newly saved workspace with the exact same parameters that I used on the original.

Thanks for taking a look!

-Mark

RE: Spontaneous X Y shift mid print

Nick,

You are welcome to join in this thread. 

I'm happy to have other people sharing their same experiences of the same problem.

More data points make finding the correct cause/solution easier.

-Mark

RE: Spontaneous X Y shift mid print

@mark-25: Oops, sorry for the confusion, at that point I was replying to @nick-brett - in your case it would only need one of the parts on the bed to warp enough to cause a crash that would lead to layer shift - and it could be any of them.

@nick-brett: there is a pattern of poor adhesion on the underside of your prints that looks like fingerprint distribution.  A really thorough clean of the print sheet (look up threads on here) might be enough to prevent crashes.  There's no sign of this in @mark-25's pictures so you are probably looking at two different causes.

Cheerio,

RE: Spontaneous X Y shift mid print

Steep overhangs tends to curl up a little. In stealth mode the collision detection is off.

The airflow of the fan-shroud may not be even in all directions. Rotating a part might help. A test print with overhangs in all azimuths may show weaker directions. The hot bed will factor in too at low z.

It is essential that the filament is dry enough. You might consider a slightly reduced extrusion factor of, say, 0.98, especially with PETG.

RE: Spontaneous X Y shift mid print

Funny coincidence but this week I experienced my first layer shift on a Core One, which looks similar to what you're seeing. It's an object I've printed literally hundreds of times on that machine, only difference is the text that gets imprinted on its vertical wall. Tried three times, each time it failed at what looks like roughly the same height though hard to tell.  Tried a previous version with a different text imprint, no problem, so for me that excludes adhesion or belt issues.

I suspect it's what Raaz was referring to:

I only had layer shifts, when using "Avoid crossing perimeters", which leads to two things: 1. A massive amount of extra commands for tiny movements, which can overload the processor and 2. Direction changes at full travel speed, without slowing down.

Indeed "avoid crossing perimeters" is on in that profile, as it is in all my default profiles. For some reason that particular text imprint seems to be something the printer doesn't like. 

In the end I was able to print it on my Mk4S/MMU3 machine, so for me it's time to move on as I don't really have the time nor desire to troubleshoot this further. But peculiar it is, nonetheless.

RE: Spontaneous X Y shift mid print

In stealth mode the collision detection is off.

As far as I know, that was only the case for the trinamic stealth mode. The core one motors just use slower settings, that you can configure in the slicer. 

The crash detection isn't the best though (currently?) since u had some nozzle crashes and there was no crash detected (normal mode).