Colour change leaves extra dot of filement on your object
After you have loaded a new filament (of a different color) at a set color change, the MK4 will continue printing. But it first puts a little dot with the new colour. And sometimes it does that in a place where you don't want it. How can you prevent the printer from extruding that extra dot?
The MK3 did not have this behaviour.
Best Answer by jkavalik:
I believe it is a slicer issue, I see the same on my MK3 color changes. The slicer puts the color change command into the layer change block, meaning it is after the last move from previous color, but before the first move from the new color, meaning the head did not yet move to the part of the model that should have the new color.
By being one Gcode command, the color change starts and ends in the same position. It would be much better if it contained the X,Y(,Z) move too but that is not very gcode-y.
Checked and yes, it is already reported (since 4 years ago) - https://github.com/prusa3d/PrusaSlicer/issues/2672 and even has an unmerged PR with a fix.
RE: Colour change leaves extra dot of filement on your object
I'm also having this problem. I suspect that the mk4 is touching off on the last position to confirm the Z height. I think this needs an enhancement to do the touch in a place that the mk4 is going to print the next (new color) layer instead of the last position, or better retraction/wipe settings so we don't have a blob of filament after the color change.
Anyone know if this is an issue in firmware or the slicer?
RE: Colour change leaves extra dot of filement on your object
I believe it is a slicer issue, I see the same on my MK3 color changes. The slicer puts the color change command into the layer change block, meaning it is after the last move from previous color, but before the first move from the new color, meaning the head did not yet move to the part of the model that should have the new color.
By being one Gcode command, the color change starts and ends in the same position. It would be much better if it contained the X,Y(,Z) move too but that is not very gcode-y.
Checked and yes, it is already reported (since 4 years ago) - https://github.com/prusa3d/PrusaSlicer/issues/2672 and even has an unmerged PR with a fix.
RE: Colour change leaves extra dot of filement on your object
Any solutions or work arounds? This is incredibly annoying as I'm generally dealing with black and white filament which have a strong contrast
RE: Colour change leaves extra dot of filement on your object
if you are doing colourchange by layer height, do the colour change one layer higher than normal, so that the extruder stops under the area where the new colour will start, so that the dot is hidden,
OR
put a piece of paper over the print, before you complete the colourchange, then let the nozzle dab on the paper, and whip the paper our of the way, so that the printer can continue printing the rest of the new colour.
have you considered adding a comment on this matter in the Prusa Slicer GIT HUB page?
that's where the Devs, hang out
there appears to be a parameter in the M600 command set, that appears not to have been implemented, in the prusa implementation
https://reprap.org/wiki/G-code#M600:_Filament_change_pause
This option, looks as if it would help, if it had been implemented.
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
RE: Colour change leaves extra dot of filement on your object
It's now December, we've had a few good firmware and PrusaSlicer updates, and this is still happening on my MK4. I'm not familiar with GitHub, is there a specific place we comment or post this issue to so it gets on someone's radar? This is suuuuper annoying.
Until a fix happens I guess I'll be holding paper under the nozzle after the color change...
RE: Colour change leaves extra dot of filement on your object
You can manually edit the gcode file to make the print head move to the new position before the color change. Just search for each color change ("M600") in the gcode file and copy the first travel command after the color change to a place right before the color change. Here is an example. The area around the color change usually looks approximately like this:
;WIPE_START G1 F9600 G3 X52.542 Y184.807 I-8.681 J-7.353 E-.16 ;WIPE_END G1 Z.6 F720 ;AFTER_LAYER_CHANGE ;0.6 ;COLOR_CHANGE,T0,#80E936 M600 G1 E0.4 F1500 ; prime after color change M73 C43 M486 S0 G1 E-.8 F2100 G1 Z.8 F720 G1 X168.8 Y160.883 F12000 G1 Z.6 F720 G1 E.8 F1500
Find the first travel command after the M600. In this case
G1 X168.8 Y160.883 F12000
and copy it to before the M600, so you get
;WIPE_START G1 F9600 G3 X52.542 Y184.807 I-8.681 J-7.353 E-.16 ;WIPE_END G1 Z.6 F720 ;AFTER_LAYER_CHANGE ;0.6 ;COLOR_CHANGE,T0,#80E936 G1 X168.8 Y160.883 F12000 M600 G1 E0.4 F1500 ; prime after color change M73 C43 M486 S0 G1 E-.8 F2100 G1 Z.8 F720 G1 X168.8 Y160.883 F12000 G1 Z.6 F720 G1 E.8 F1500
This works for me. You will still have to manually wipe the print head while it moves to the new location to remove the material extruded when the nozzle is primed.