First layer issues when using Complete Individual Objects on subsequent parts.

[bluerider098]

Printer model

XL

Firmware version

6.1.2

Upgrades and modifications

None

Printing from...

USB

Describe the bug

Using the Complete Individual Objects I often get first layer issues on some of the parts printed after the first one. I believe the issue is related to the fact that the shape of the bed changes over time as it heat soaks, and possibly from the adjacent completed objects possibly changing the shape of the bed, or possibly the bed mesh is not being applied to subsequent parts.

How to reproduce

Run any print where the 2nd part is 40 or so minutes after the first. The nozzle will be too far off the bed for the first layer.

Expected behavior

Not sure what the issue might be as I didn't know how the bed mesh is applied to these type of prints.

Possibly a new bed mesh is created in the area of the subsequent parts before it's started. I realize that oozing and the fact that the mesh area may need to be smaller to avoid hitting the already printed parts makes this solution far from ideal.

Another better option might be to apply a nozzle offset that's applied to any parts printed after the first.

I don't have a good answer, but it's only an issue when using Complete Individual Objects. If the parts are printed all at once the first layers are good.

I'm my particular case the parts that I am printing have a very tight tolerance and the parts come out different sizes when printing as an individual vs. printing a group of them. I have narrowed the issue down to the fact that the amount of cooling time between layers is much greater when printing multiple parts vs. a single part. So by using the Complete Individual Objects feature my problem is solved because the cooling between layers is always the same.

Files

No response

[danopernis]

@bluerider098 can you please provide minimal G-code which exhibits this behaviour and photos of the failed first layer?

[bluerider098]

I unfortunately don't have any pictures, but will rerun a print tonight and get some pictures as well as share the gcode.

[bluerider098]

@danopernis Attached are some pictures exhibiting the issue. You can see how the front sides of the parts did not adhere well to the bed. One of the objects

The other picture shows a 1st layer that I stopped that was not good. Here also is a link to a video as it was printing.

https://youtu.be/eTh87xrT6aE?si=GmFg8CvzWfxgB-fC

Now if I run this exact same group of parts, but turn off complete individual objects it'll print just fine.

[bluerider098]

[bluerider098]

@danopernis Is there any way to send you the gcode privately? I'd prefer not to share it publicly, or I can try to reproduce the error with something simple like a cube. Which would you prefer?

[CZDanol]

Hmm, there are different temperature settings for the nozzle and the bed for first and non-first layers. Do these differ for your profile? Could be that the first layer settings is not applied for subsequent objects, or that the nozzle/bed do not heat up/cool down fast enough for the further first layers.

[bluerider098]

Hmm, there are different temperature settings for the nozzle and the bed for first and non-first layers. Do these differ for your profile? Could be that the first layer settings is not applied for subsequent objects, or that the nozzle/bed do not heat up/cool down fast enough for the further first layers.

Yes I'm not really sure. The only thing I change in the slicer settings is the complete individual objects. That was my reason for starting this issue because I'm scratching my head on trying to figure out how to make this work. I've had some success by lowering the live Z while the first object is printing, but that's been hit or miss on completing good parts.

I think it's that the shape of the bed changes as parts are printed and everything warms up, but that's just a theory. I don't know enough about how the printer uses the bed mesh etc to analyze it any further.

[bluerider098]

@CZDanol I think you're onto something with the different bed and nozzle temperatures for the first layer.

I did more testing and made the heatbed temperature the same for the first layer as the rest of the print and did the same for the nozzle temperature. Doing this I've done 2 successful test prints. Tonight I'm going to run another test print, but much longer, approx 14 hour long print to see how that performs.

[CZDanol]

@bluerider098 thank you for your report. I'll await your conclusions and potentially forward the issue to the slicer team, because that would probably be their domain.