this post was submitted on 11 Nov 2023
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45
First mm always faulty? (feddit.de)
submitted 2 years ago* (last edited 2 years ago) by [email protected] to c/[email protected]
17 comments fedilink hide all child comments
 

IMG_20231111_205431

I cant get my Anycubic Kobra 2 with Klipper to print correct. The first mm of each layer are faulty, resulting in a bad tooth in gears.

I tried to slow down the print, tried to minimize/deactivate retraction, fiddled with z offset and first layer height, lowered bed temp, altered the extrusion rate. Nothing works. Everything else seems fine, slim z seam, nice walls, no over/underextrusion.

Anyone got a hint how i could fix that?

Edit: I cancelled that Print, the Problem is only in the first tooth:

IMG_20231111_212736_745

the tooth in the marking should look like the ones above it.

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[–] [email protected] 15 points 2 years ago (1 children)

Try adding a skirt to your print in your slicer. That should ensure that your nozzle is good and primed by the time your printer actually starts printing the first layer of your part.

I don't know in what order that layer was printed, but it looks to me that no material was leaving the nozzle throughout the 7:00 to 3:00 or so portion of it.

[–] [email protected] 2 points 2 years ago (1 children)

I canceled the print. Its only the first tooth thats not printed correctly.

IMG_20231111_212736_745

IMG_20231111_212741_084

[–] [email protected] 7 points 2 years ago (1 children)

I can see that your printer is doing some nozzle priming lines on the side of the bed before it starts the actual print.

Does it retract after finishing the priming lines? It may be retracting too far/not recovering far enough before it starts the print moves, and depending on the slicer and printer firmware specifics, that function might not be controlled by normal retraction settings.

[–] [email protected] 3 points 2 years ago (2 children)

I changed every retraction setting ive found. 2x in PrusaSlicer, 1x on Klipper, nothing changes. But with Cura Slicer the problem is gone. So i obviously f*ed up some setting in PrusaSlicer. Will test more today.

[–] [email protected] 2 points 2 years ago (1 children)

Are you printing internal or external perimeters first?

[–] [email protected] 1 points 2 years ago

In PrusaSlicer externals first, in cura outside to inside. Whats weird in cura, it prints the outter wall ls first half gears first, then the spokes from the second half.

[–] [email protected] 2 points 2 years ago (1 children)

That is interesting. Does CuraSlicer do the same priming lines? Have you tried the print with PrusaSlicer without the priming lines?

If you can figure out what Cura is doing differently in that section of the gcode you could put those lines in the custom gcode box in PrusaSlicer and get the same results.

[–] [email protected] 2 points 2 years ago (1 children)

It does the same priming lines, im using the same start gcode. Without it would miss the complete first half of the gears outter wall, oftem from the 5 lines only 3 get printed.

[–] [email protected] 1 points 2 years ago (1 children)

Right, ok, so I'm not particularly familiar with Cura... I use SuperSlicer which is a fork of Prusa (which is a fork of Slic3r). Neither slicer has a UI option for initial purge lines as far as I can tell.

So for both Prusa and Cura you are using a block of custom start gcode to define the purge lines? Exactly the same gcode in both slicers?

Could you please share the Cura gcode output in addition to the Prusa version you shared? I am curious what the difference is.

[–] [email protected] 1 points 2 years ago

https://filetransfer.io/data-package/Ag7tLgc5#link

yes, its the same gcode/lines. In Prusa its possible to alter Printer Gcodes, in Cura not. There might be differences.

[–] [email protected] 3 points 2 years ago (1 children)

Could be pressure advance related. Have you tried disabling it or retesting your value.

[–] [email protected] 2 points 2 years ago

Should be a slicer problem, with cura its gone...

[–] [email protected] 3 points 2 years ago (1 children)

My guess is that is a slicer error because it couldn’t make the shape with a combination of the tooth size on the gear and wall thickness settings. Does it look right in the slicer after it is sliced on the first layer?

[–] [email protected] 2 points 2 years ago

It looks correct in the slicer. I changed the slicer btw and with cura everything works fine. So its something in PrusaSlicer. Will test some more today.