Catharsis

[3D Printing Tips and Tricks]

I've been experimenting with making color prints on the Prusa XL and it's taking a major toll on me.

Initially I was getting amazing results on a number of objects that I've been finding on Makerworld. The kind of objects I've always hunted for to really take advantage of multicolor FDM. I'll share these results in another post at a later time when the smoke stops coming out of my ears... but for now... Sorry... Gotta rant.

It all starts with the latest firmware update from Prusa. 

I suspect the way Prusa and Bambu do their testing is to have a bunch of machines, each with a video camera on them. The tester starts the test print and WALKS AWAY. Then later they review the vid. This has to explain why both BONEHEADED companies make the user stand there and wait and wait and wait at the start of every print. They are completely clueless about the user experience!

With this latest FW update Prusa heats up the first extruder to 170 and then homes the bed, then they have the extruder cool to 70 (!) and they clean the nozzle, then they heat it up again and home X and Y then they heat up the bed and then probe the bed EVERY TIME. At least 10 minutes of standing there! So to get to the start of a print is now a major PITA!!! Same for Bambu, but at least Bambu gives the user the option to not do a number of these startup routines for every print. They just do not get it. I get the impression that both companies do not have optimal people.

Moving slowly forward...  I start to get my first layer and right away I see a major problem. This time though it is caused by Prusa slicer and it's paint on color methiod which is the same for Bambu BTW... A surface color translates within the print as a triangular extension that extends into the center of the print. The depth of that extension is predetermined by the slicer and the user has no way to refine it. The result is you can easily get a very very fine point that extends into the print and the material paints over itself which makes a big BLOB that the nozzle crashes into. Thanks to the short sightedness of the people that wrote this crap there is no way to prevent this. As such I pause the print and use a nippy cutter to remove the blob... and Prusa has somehow broken their pause with the new FW update. You can't resume. Print ruined.

Its days like this I wonder just how viable FDM 3D Printing actually is.

[Bryan Eckert]

I believe Bambu has an indirect way in the "strength" tab. There is a setting in there called "color depth". Maybe poke around in Prusa Slicer and see if they have something similar added in.

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[Bryan Eckert]

Also, you can control the depth by using placed modifiers, which is certainly way less ideal than a setting but it can be done.

On Wed, Jan 7, 2026 at 2:57 PM 3D Printing Tips and Tricks <3d-printing-...@googlegroups.com> wrote:

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[Kurt A 3d]

My notes on coloring are in this writeup of mine: https://www.printables.com/article/kurt-as-non-obvious-to-him-at-least-prusa-slicer-s-YNYgb2d   (section 5 Color)  I find "slicer painting" to be the most labor intensive way and the last resort. 

I do lots of complex stuff, but I am willing to run the wipe tower.    Also, at this point for the doll bed, I don't stint on support material :-) 

Kurt-A

[3D Printing Tips and Tricks]

I don’t understand… there’s nothing in your write up that says anything about the problem I described.

The way it is right now facet painting is a sealed black box. The user can’t influence anything that the slicer generates. I note the extreme similarity between Bambu and Prusa’s facet paint functions which also looks exactly like the now defunct commercial product that was released years back… as such it would not surprise me if the two companies simply lifted code.

Simple coloring of cohesive shapes that are easily abstracted with discreet lines of facets are the only reliable thing that can be colored reliably with facet painting and that method is significantly inferior to the older approach of parting the object and have separate colors per part.

So… the bottom line is fdm color is still quite limited.

[3D Printing Tips and Tricks]

Yeah... modifiers... as other have written out there... it may be easier to simply redesign it in CAD...

BUT!!!

I cannot believe this! I actually found how to set the depth! I tried EVERY setting and sure enough... As in everything Prusa, their terminologies and language never makes any sense...

It's in Print settings, Advanced, Maximum Width of segmented Region AND Interlocking Depth of a segmented region.
Worked!

[Kurt A 3d]

I am not surprised at the similarity between the slicers. I mean Slic3r begat PrusaSlicer and Cura.   PrusaSlicer begat BambooSlicer.  BambooSlicer begat PrusaSlicer.  All the source is by licence agreement in the public domain and they all read each others code and 'share' features.  

Bamboo did change the way colors are represented in the 3mf file so you can't move coloration from one to the other.   (notes on this later in this message).

Anyway as Bryan says you can use modifiers carefully placed rather than painting to have a finer control of the depth in the model that the color is present.  Probably because of transparentish fillament they by default project the color as a slice into the model by default.   This 3mf file: https://www.dropbox.com/scl/fi/kdvd79qzze608typcnwfv/colorexamples.3mf?rlkey=9e4yyinl9xzwflfo9yejikybk&st=swz6vnah&dl=0 

 has 5 different paintings of the same dragon. 

The one on the back left:      Brush Sphere SplitTriangles

The one in the back middle: Brush Circle SplitTriangles

The one in the back right:     Brush  Triangles (SplitTriangles makes no sense with this brush)

The one in the front left:       I used Sphere shaped modifiers

The one in the front right:    I used cylinder shaped modifiers, had to rotate one

If you scroll through the sliced models you will see how the two modifier based versions only do the painting WITHIN the modifiers shape. 

This model had no Parts, if it did and you colored by choosing the parts then the colors would be confined to the parts in question.  Of course this is with the default "advanced" settings.  Some of these options have interesting impacts on all sorts of stuff: https://help.prusa3d.com/article/mutliple-extruders-settings-interlocking-advanced-bonding_867124

NOTES ON 3MF INCOMPATIBILITY:

The spec:

https://3mf.io

PRUSAS TAKE ON THIS:

https://github.com/prusa3d/PrusaSlicer/issues/12502 

"it might be interesting to first describe how the problem came to existence.

The reason why color painting is lost when loading 3MF files from BambuStudio is because BambuLab forked PrusaSlicer and for some reason changed the key under which the painting data are stored. PrusaSlicer saves them at each triangle using slic3rpe:mmu_segmentation attribute (as it always had), while BS changed the key to paint_color. The format of the data and its location is AFAIK the same. I have no idea why the change was necessary, it seems to be a completely unneeded compatibility-breaking change. My impression is that the incompatibility you "beg" us to fix is there simply because BambuLab decided it should be there and made it so.

It is also worth mentioning that adding an XML tag without a namespace prefix (the slic3rpe:) is not allowed by 3MF Core Specification (see here). I will not claim that PrusaSlicer is perfect when it comes to following 3MF specs, but this change actually made it worse. (Despite the claims about adhering to 3MF Core Spec in the BS 1.8.4 release notes.)

Technically, we can still load the data by looking for either paint_color or slic3rpe:mmu_segmentation and treat both attributes equally. We will probably do that in the next release. However, I don't exactly like the idea of implementing support for things that our forks deliberately break..."

OPEN SCADs take on this:

https://github.com/bambulab/BambuStudio/issues/4292.  Last comment is someone working on Blender (another tool)

TOOL THAT MAY KLUDGE/FIX THIS:

https://github.com/raistlinJ/3mf_bambu2prusa

[Kurt A 3d]

Ah I see while I was writing my reply you found the advanced settings. 

[3D Printing Tips and Tricks]

now... the absurd heat up cool down addition to the fw...

This time instead of skipping the "Absorbing Heat" cool down I watch it real carefully. It looks to me that someone came up with the idea that any material outside of the tip of the nozzle which could make cleaning and subsequent probing problematic is easier to remove if after heating the nozzle to 170 then letting it cool to 70 then heat it all up again (!) the material will come off during the cleaning. It seems to ... it would also be a heckalot more reliable if they ALWAYS retracted filament out of the melt zone whenever a tool is parked and park all tools at the end of a print and after a filament load.

Can you imagine how awesome an FDM printer could be if the brightest people were involved instead of those who are currently doing it?

[Kurt A 3d]

They HAVE increased the retraction in the supplied filament profiles similar to what you said they should long ago. 

Fillaments->Fillament Overides->Retraction when tool is disabled->Length-> 20mm

The reason they do this as part of the fillament profile is, I believe, so that they don't do it too much for TPU/PEBA etc.  While the default for Prusament PLA (and most other filaments I have looked at) is 20, when you look at Prusament TPU its "6".   This is most likely because retracting TPU leads to worse things than some stringing.  

They do improve things, though of course slower than one would like.   They have improved the sequential printing so it is somewhat less likely to collide :-), and also there has been some improvement when you use the NO SPARSE LAYERS wipe tower option so that it now tries to move to the maximum Z offset on error, though I wouldn't bet that they have all the cases handled. 

Also the TUNE menu now will let you, in theory, change the fillament in a tool other than the one that is currently printing.

I do wish that when you PAUSE a print they would move to maximum Z reached (or maximum Z) and move the tool to the FRONT instead of the BACK of the printer.  Sigh, maybe someday.    

This was my list of enhancements I wrote I wanted last May (They have done one of the 5 so far):

1) XL: The ability to add the MMU3 to toolhead #5, for those days when 5 colors are just not enough :-)

2) Prusaslicer:   Bracketing the WipeTower in the Gcode (I can almost see how to do this with a post processing script) so that it is a cancelable object. For those days when it’s the @#@! WipeTower that fell over, but the model would probably finish ok without it.

3) XL: The ability to “tune” a print to add a filament join.   For those days when you thought you had enough filament but now 15 hours later you see the end of the spool and you would just like to be able to go to bed and have it switch to that other spool

4) XL: The ability to “tune” a print and load filament onto an extruder you weren’t useing, or is not currently printing now (see above) - yes it will pause the current print and have to swap toolheads twice…. DONE !!!

5) XL: The ability to have different heat bed tiles at different temperatures. For those times your printing a dummy13 and want the PETG joints over here and the PLA armor over there - ok this is a silly ask 

I would add to this:

6) XL: The ability to assign a toolhead to be used as well as to be spooljoined to, also the ability to spool join from multiple toolheads to the same one.   Basically, lets say I have a 5 color Print, I would like to be able to say, OK, if Color 1 runs out, its ok to use toolhead 3 as both color 1 AND color 3 etc....   

Of course I have found out how to do the spool join over prusaconnect and not just at the printer, which is nice.   

Kurt-A

[Kurt A 3d]

Hey, I just found this guide on the Prusa Website: https://help.prusa3d.com/article/multi-material-painting_262620

It discusses the whys and how to control the painting

“Segmenting colors

During slicing, the painted regions are cleverly extended inwards, giving the different colors/polymers the best chance of binding together.

The object surface is segmented into patches of the same material and the patches are extended inwards. The regions painted at the top resp. bottom surfaces are extended by the number of top_solid_layers resp. bottom_solid_layers (configurable in Print Settings - Layers and Perimeters). The regions painted at the side walls are expanded inwards up to maximum mmu_segmented_region_max_width (which is a new configuration parameter accessible in Print Settings-> Multiple Extruders-> Advanced).

The painting only affects the slicing result, the model itself is not altered and the colored "parts" cannot be exported separately.”

I assume that the “resp.” In the above is a text processing typo for “/“.   

Kurt-A

[Bryan Eckert]

I didn't get to poke around in Bambu studio last night, I'll look around and see if they have a similar setting there.

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[Bryan Eckert]

Orca is the same as PrusaSlicer per your description. 

Bambu doesn't seem to have this enabled - they only have "interlocking depth".