BUG Bizarre Z Position Glitch of Some Sort

[CCLMakerSpace 2]

Hi Folks,

 

I have this dual extrusion print where one object is encased entirely inside of another. It has printed very well several times so far, so I know there's nothing wrong with the object itself. However, on the most recent print of it, I switched the infill from Triangle to Cubic Subdivision. It caused the strangest behavior, I can't for the life of me understand it...

 

Basically, It starts out fine, but over time the Z position slowly starts drifting. It starts grinding the nozzle against the surface of the print. By a handful of layers later, the printhead is smacking against the sides of the object when it moves. If you let it keep going it errors out, and then smashes the printhead into the wall and the bed into the floor, like it has no idea where anything is. Then it throws an error about the endstops.

 

It took me several tries to figure out that it ONLY does this when I use Cubic Subdivision. And what's weirder, I've never had trouble using that infill pattern for other objects. It's something specific about the duel extrusion nature of this print, plus that infill pattern. I haven't tried other patterns, but I'm guessing it's related to whether or not a pattern changes in the Z direction.

 

Is this a known issue?

 

Thanks,

Remy

Edited October 27, 2022 by CCLMakerSpace

[MariMakes 198]

Hey @CCLMakerSpace,

 

Thanks for your report 👍
That's super interesting and I can imagine quite frustrating. 

Do you have pictures of your zseam?

A project file would also really help. It contains the printer and settings we need for troubleshooting. 
To save a project file go to File -> Save project.

[CCLMakerSpace 2]

I didn't bother, since switching to a different infill pattern fixes it. Maybe if I get a chance, I'll recreate the problem and upload those for you.

[CCLMakerSpace 2]

Ok, I finally got around to at least grabbing the program file. Attached here.

UMS5_Jigglypuff_in_Pokeball.3mf

[MariMakes 198]

Hey @CCLMakerSpace,

This looks like an enormously tricky challenge 🥴

I've been trying to see what you mean with trailing Zseam because mine looks like this in Cura 5.2.1:

Do you have a picture of how your printjob fails? Or how your zseam looks like? 

If I were you I would switch to lightning infill for this printjob, depending on how seethrough your PVA walls are. 
 

[CCLMakerSpace 2]

It has nothing to do with the zseam and I never said it did, sorry, I think you're misunderstanding the problem. It's hard to explain. Basically as the print goes on, the z POSITION drifts. As in, it's printing too low in the Z direction. It gets worse over time, until the nozzle is like several mm lower than the actual current height of the object, and keeps slamming into it. You can't see the problem from the project file.

Edited November 10, 2022 by CCLMakerSpace
Added more info

[MariMakes 198]

Ohhhhh, I think I understand what you mean.

During your printjob the sphere starts curling up.
The warped material starts pushing against the nozzle and is limiting extrusion.
It's quite common in spherical shapes like this. 
 


In that case, temperature control is super important! 
You want to prevent that the printjob cools down to fast, and if it does cool, it does so evenly. 

Can you limit the airflow around this printer? Move it away from a door, walking path, attach an airmanager or place a box over the printer? 

Personally I would start experimenting with increasing the temperature of the bed, nozzle, and find ways to decrease the cooling. Maybe consider adding more walls or enable support. I would start looking for remedies against Warping and Delamination. 
 

[CCLMakerSpace 2]

That's not the case. There's no warping visible at all, and it's happening even in the interior of the object. The difference in level is wayyyyy beyond what could happen with warping anyway. And it only happens on one specific infill pattern.

Edited November 10, 2022 by CCLMakerSpace

[CCLMakerSpace 2]

Hopefully this crude MS Paint diagram will explain better. The pattern you see in Example 1 and Example 2 just keeps getting worse and worse if you let it, and then it eventually fails and exhibits the strange behavior I mentioned in the original post, about slamming the print head into the wall, and slamming the bed into the floor.