[Poll] Do you have layer shifts when printing multiple PETG objects?  

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

i manually changed the z-hop from 0.2 to 0.4mm. I think this fixes the issue, dont have any layershifts after a couple of prints.

Thanks to point at this really easy solution. Its kind of obvious when you think about it, didnt know you can adjust the Z-hop hight. Thanks for the tip!

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

That's great news.  Have your PETG IS enabled prints been working well now?

RE:

It happened to me once, after I heard a *bang* and I suspect the nozzle collided with one of the parts and the Y-axis motor jumped steps.

This has also happened to me with an Ender 3 at work printing PLA, so I suspect a bug in the slicer sometimes rears its ugly head. Or if variable layer height is being used, perhaps it doesn't always keep clear of other instances of the part when moving from one to another.

Increasing the Z-hop distance will probably fix this as suggested.

If someone attaches a tiny camera and flex cable to the carriage looking at the nozzle, a lot of these issues will be made visible and sorted once and for all!

John Dom

RE:

Yes, I have when printing pla. Brand new kit, prints great, beautiful first layers. But layer shifts! What can i do? Do I have to disable IS? One of the main reasons for buying the expensive machine with lots of equal competitors. I´m not happy

RE:

Still observed with Slicer 2.8. In 2.7.4, I had repeated layer shifts with Prusament PETG when using Input Shaper, printing the same object without Input Shaper (yes, it takes twice as long) worked perfectly. First two attempts with IS in 2.8 failed again, no IS test is on the printer right now.

Since there are no non-IS profiles for the Mk4 with MMU3 - is there any way to disable the IS?

The usual causes of this sort of thing are warping and poor first layer adhesion.  Have any of you checked the underside of failed prints?

Cheerio,

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

checking the ten or so failed prints in my wastebasket - nope, bed adhesion and print undersides are perfect. using the satin sheet, so any issues here would be quite obvious. same argumentation applies : why would IS prints fail reproduceably (but always at a different layer) while non-IS prints succeed?

going to run another attempt this afternoon - I'm using an obxidian nozzle, could be that what works for the slow speed is just not reliable any more at higher throughput. I'll try upping the temperature by a few degrees.

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

Yeah its getting pretty annoying, don't like input shaper due to failed prints but its the only option if you have an MMU

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

Posted by: @markus-6

checking the ten or so failed prints in my wastebasket - nope, bed adhesion and print undersides are perfect. using the satin sheet, so any issues here would be quite obvious. same argumentation applies : why would IS prints fail reproduceably (but always at a different layer) while non-IS prints succeed?

This seems somewhat logical (that it fails with IS more often):  IS results in faster speeds and more importantly faster acceleration on the X and Y axes, so any pulley (grub) screws that are marginal in their grip, or belt tensions that are marginal, will fail more often.  If your failures happen only in IS, that's the first place I'd look.

Once you've played with those (and I'd even adjust the belt tensions up and down from what appears to be the optimum, just to be sure), then you'd consider less obvious things like some kind of delays or non-linear behaviour of the filament being extruded (like maybe there's "filament momentum" when it's being extruded faster or something), or some other weird effect.   IS having bugs is also an option but many prints are succeeding and layer shifts would be exactly reproducible with the same gcode if that was the case.

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

I had just one. I could say that printing in PETG is more difficult than PLA, and the speed should be kept slow due to low volumetric speed. I have the same issue sometime on the FLSUN V400 at high speed with PETG. However I know in advance when it is about to happen, since it happens only in specific conditions:

• bad / humid PETG that has vapour or bubbles.
• wrong infill type for the speed used. Gyroid is the best that does not cause problems. Rectilinear is the worst and creates irregular lines.
• Strings that are present on the infill and on the perimeters.
• Nozzle that start scraping the perimeters and the infill.
• Material attached to the nozzle that starts scraping the just printed part, creating balls of material that enlarge themself and increase the material on the nozzle.

When those situation become true, you start hearing the nozzle scraping the infill, then the perimeters, and then you see the nozzle covered by plastic, until the plastic is big enough that it violently hit the object borders, since it could not move over the object any more, and then the layer could shift, or the object detaches from the bed.

Regards

RE: [Poll] Do you have layer shifts when printing multiple PETG objects?

I get this in PLA as well, it's very annoying to the point where I just use the "legacy" non-input profiles. I was hoping there would be a fix but I guess the input shaping just isn't there yet?

Maybe it will be working for more users with the S upgrade.