Help with color change on layer
 
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ScoobyDoo27
(@scoobydoo27)
Active Member
Help with color change on layer

I do a lot of printing where I change the color on after a certain amount of layers. Sometimes this causes an issue because after the color swap the nozzle goes back to where it left off and the nozzle will leave a little blob of the new color on top of the 1st color I used. Is there a setting or some sort of custom g-code I can use so that the printer will always finish the 1st color layer where the 2nd color will always print over? I used to use a wipe tower when it was an issue but now in prusa slicer 2.6 the wipe towers are basically useless, they are super small and they have the same issue of the nozzle going back to my print and leaving a blob before the nozzle moves over the wipe tower.

I hope what I'm asking makes sense. Thanks in advance for the help.

Posted : 23/07/2023 2:32 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Help with color change on layer

I had this problem when using colour change by layer height to colour text on name badges, and found that if I printed the first layer of the text with the base colour,  the colour change process returned to the last point where it printed, which was under the new colour and that resolved the issue. 
Another option, if this is not possible, is to put a piece pf paper under the nozzle, when you do the colour change, so that when the printer re visits the last section end point, it blobs on the paper, BUT, you have to pull the paper out of the way, quickly. 

note, some Gcode information pages suggest that using the suffix ' N '

M600 N    
would prevent the printer returning to the last point, after a colour change, but that doesn't seem to work in Prusa Firmware,

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 24/07/2023 8:23 am
Chris Hill
(@chris-hill)
Estimable Member
RE:

I used to see the same problem when doing a manual colour change for different objects on the same layer.  Then I learned that I'd missed some settings for this 'Manual Multi-Material' approach.  There's some discussion of this in this thread.

It turned out that enabling the "Single Extruder Multi Material" option, in conjunction with the wipe tower, caused the nozzle to print a small part of the wipe tower BEFORE initiating the filament change.  This had the desired effect that after the filament swap the nozzle returned to the wipe tower, rather than the print, so any mess left over from the swap doesn't spoil the print.  This prevented the unwanted 'dob' of the new colour behind the old colour.

I've never experimented with colour changes by layer, but I can imagine that the 'Single Extruder Multi Material' option may not play the same role in your case.  But maybe selecting this option is enough to change the behaviour of the wipe tower - i.e. so that the point the nozzle returns to is the wipe tower, rather than your print.  Worth a try.

Posted : 24/07/2023 1:04 pm
ScoobyDoo27
(@scoobydoo27)
Active Member
Topic starter answered:
RE: Help with color change on layer

 

Posted by: @chris-hill

I used to see the same problem when doing a manual colour change for different objects on the same layer.  Then I learned that I'd missed some settings for this 'Manual Multi-Material' approach.  There's some discussion of this in this thread.

It turned out that enabling the "Single Extruder Multi Material" option, in conjunction with the wipe tower, caused the nozzle to print a small part of the wipe tower BEFORE initiating the filament change.  This had the desired effect that after the filament swap the nozzle returned to the wipe tower, rather than the print, so any mess left over from the swap doesn't spoil the print.  This prevented the unwanted 'dob' of the new colour behind the old colour.

I've never experimented with colour changes by layer, but I can imagine that the 'Single Extruder Multi Material' option may not play the same role in your case.  But maybe selecting this option is enough to change the behaviour of the wipe tower - i.e. so that the point the nozzle returns to is the wipe tower, rather than your print.  Worth a try.

I'm not seeing the 'single extruder multi material' option anywhere in the slicer. Where might that option be?

When I used wipe towers prior to PrusaSlicer 2.60, the printer used to print a small piece of the wipe tower prior to changing the color so the nozzle would always return to the wipe tower instead of my print. But they changed how the wipe towers function in 2.60 and the printer no longer does that.

Another option, if this is not possible, is to put a piece pf paper under the nozzle, when you do the colour change, so that when the printer re visits the last section end point, it blobs on the paper, BUT, you have to pull the paper out of the way, quickly. 

I will have to try the paper option. I don't know why I have never thought of doing that.

Posted : 28/07/2023 1:54 am
Chris Hill
(@chris-hill)
Estimable Member
RE:

 

Posted by: @scoobydoo27

 I'm not seeing the 'single extruder multi material' option anywhere in the slicer. Where might that option be?

When I used wipe towers prior to PrusaSlicer 2.60, the printer used to print a small piece of the wipe tower prior to changing the color so the nozzle would always return to the wipe tower instead of my print. But they changed how the wipe towers function in 2.60 and the printer no longer does that.

It's under 'Printer Settings' -> 'General' -> 'Capabilities'.  It's only available if you increase the number of extruders.

I only mentioned it because it changed the behaviour of the wipe tower for me when doing more than one colour on the first layer.  Without ticking that option the material swap would happen then the nozzle would return to the print before moving to the wipe tower.  After ticking that option it creates a small section of the wipe tower before doing the material swap, and then the nozzle returns to the wipe tower.  So even though you don't strictly need to define more than one extruder to do colour changes by layer (I think - never done that myself), I wondered if this option would modify the wipe tower to be more useful in your case.

By the way, there's a search facility in PrusaSlicer to help you locate specific settings - click on the magnifying glass at the top of the page, and just start typing the name of the option.

Posted : 28/07/2023 9:09 am
Chris Hill
(@chris-hill)
Estimable Member
RE: Help with color change on layer

I just did some quick tests.  Adding another extruder, enabling 'single extruder multi material', and enabling the wipe tower, make no difference if you just define a colour change at a specific layer.  The wipe tower doesn't seem to be used for simple colour changes (unless I've missed something).

But if you set up your printer to have 2 extruders, and then define an extruder change at a specific layer, the wipe tower will print, and you can take advantage of the effect of the 'single extruder multi material' setting, which is to make the filament swap happen during the wipe tower, not during your print.  No more blob.  In this case, the wipe tower serves the same function as the sacrificial object that was suggested in other threads (such as this one).

If you do go down the route of setting up a printer preset with 2 extruders, I'd recommend applying all the settings described in this thread.  Most of the settings are summarised in this post.

Posted : 28/07/2023 11:29 am
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