PrusaSlicer - Prusa XL Multi - First Layer missing in various sections
 
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Revel
(@revel)
Eminent Member
PrusaSlicer - Prusa XL Multi - First Layer missing in various sections

This has been highly frustrating and i'm looking for solutions or things to try. This issue is all inside Prusa Slicer

I have various layers of filament printing on top of various layers of filament. Think of it like PLA Black for 6 layers with PLA translucent Red for 4 layers on top of it. Some might be green on top of red.  Almost like layering stained glass.

I bring these OBJ files in just how you would guess. But the problem is it feels at random with different configurations and things that the first layer is missing on random portions of the entire setup.  If I attach all the objects together in my DCC app its fine. But so long as it is a multi object setup this can (but not always) show up. 

Sinking does not help. I have tried heavy sinking to no avail.

Doing different configurations an moving objects around can help but also just move the problem to a new section.

This is only the very first layer every single time. Layers 2 and up are always fine.

This has been across quite a few different configurations and obj files.

In DCC all bottom faces are at exact points. On the same plane.  In DCC All layered objects are right on top of each other with no penetration.

I just tried one right now where it will print fine sideways. If I rotate it 90 it has the issue. If I leave it sideways its fine.  
Going to print this one like that, but still curious what this is about.

Posted : 05/11/2024 5:08 pm
Revel
(@revel)
Eminent Member
Topic starter answered:
RE: PrusaSlicer - Prusa XL Multi - First Layer missing in various sections

Currently my best workaround for this has been to rotate the print 90 degrees in Z.  Sometimes spinning it sideways makes it work, which is ofcourse super strange.

Doing 5 extruders on a large printer with layers of transparent filament has been a bit challenging.  One is that I have to keep my prints away from the front right (looking at the printer) corner because the extruder can knock right off during printing.   PETG oozing. 

 

Posted : 07/11/2024 4:40 pm
Diem
 Diem
(@diem)
Illustrious Member

Slice a print that shows the problem. Save your project as a .3mf file

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.  Include a picture to show the detail.

One is that I have to keep my prints away from the front right (looking at the printer) corner because the extruder can knock right off during printing.

Look (from the side) and check your nextruder docks are exactly in line.

PETG oozing.

What size nozzles are you using?  Unless they are large this is usually a sign that your filament is damp.

Cheerio,

Posted : 07/11/2024 6:02 pm
Brian liked
Revel
(@revel)
Eminent Member
Topic starter answered:
RE: PrusaSlicer - Prusa XL Multi - First Layer missing in various sections

Thanks!

Rar file attached which includes images.

I received the .6 setup and have been using that.  Actually now that you mention it, I had the printer at my friends shop for a long time and he was having to lower temps and wipe PETG a lot with a brush so it wouldn't mess up on first layer. I always suspected his (auto) shop (often the doors are open!) is a bit wet and I've brought it up to him before.

Now that its back at my place inside my house and the nozzles do ooze for a bit but I've never lowered the temps and I've not seen the issues he has to the level he has experienced it. I might have some first layer wackiness now and then but in his shop it would just print in the air if you didn't baby sit it.

Thanks! I will tell him about that. In my case its just PETG oozing for a bit when i first install it then i'm good.  I can get some stringing but its pretty minimal overall.

I am in a print but took pic of back, and this is what I'm thinking you are talking about. Looks like 1 and 2 are in the same position. 3 is pushed back a bit more and then 5 is quite further back than that.  

I'm not sure how this affects things or what it means.  How does this affect things and how do I fix it?

My friend experienced this the most at his shop and he said what happens is the extruder moves so far to the front left that it hits smacks the pins, releasing the extruder.   Also he believes that that corner has had first layer/leveling issues too and was trying to keep prints away from there if possible.

Thanks again!

 

Posted : 08/11/2024 6:03 pm
Diem
 Diem
(@diem)
Illustrious Member

The bottom layer of the part is not even, some areas are not actually touching the surface so no bottom layer is generated there, it's only 0.001 mm or so but enough to throw the slicer off.  Go back to your design software and ensure all the bottom shapes are dropped to the same level.

Oozing and stringing are signs of damp filament; dry it (and keep it dry) and many problems miraculously go away.

Looks like 1 and 2 are in the same position. 3 is pushed back a bit more and then 5 is quite further back than that.

When installing them the docks MUST be pulled all the way into position; it's easy to miss the last quarter turn as it comes tight. Even a millimetre out of place is enough to mess with the docking mechanism.  Tighten them, recalibrate, and try printing again.

Cheerio,

Posted : 09/11/2024 1:11 am
Brian liked
Revel
(@revel)
Eminent Member
Topic starter answered:
RE:

Huh, then why does it work if you rotate it 90 degrees in the slicer?

I tried moving the objects in DCC to 0.0.0 in 3d and set everything based on an exact vert locations in space. 
Also it would shift around what would disappear or not. Like it seemed to change on me. 
I know that some of these are done far away from 0.0.0 so i was thinking the accuracy of the vert locations are off. But I recall doing a test at 0.0.0.

Also please try sinking. as stated in my first post was saying heavy sinking doesn't work.  I just tried ir right now and it still doesn't work, regardless of level of sinking (pulling it down in to the plate)

I will check on the extruders.  Its funky because they all latch and pull out fine. I get great prints where things line up correctly across mult extursion prints. They click and unclick in with no issues across many prints we've done.  Its just in the far far corner where it has issues.  But I can definitely dig in to adjusting those, thanks!

 

This post was modified 1 month ago by Revel
Posted : 09/11/2024 1:27 am
Diem
 Diem
(@diem)
Illustrious Member

You might even be benefitting from the slightly loose toolhead ... where the print sheet is not perfectly level (they can never be perfect) the first layers are adjusted to correct - but sometimes a high point is high enough to catch on to the second layer.  This is not a tall print so the first layer adhesion is not tested.

Re sinking: An alternative in the slicer if you have no better way; use the cut function, manally enter the Z at 0.2mm and discard the trimmings.  Now the underside is level.

Cheerio, 

Posted : 09/11/2024 1:47 am
Brian liked
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