Two-color printing error

[klickon 0]

Hello everyone.
I use 3D printer Geeetech Mizar M. I still have a problem with dual printing of two-color models that I slice in UltimaMaker Cura 5.4.0 software. I use Prime Tower for dual extrusion printing. This error appears whenever I print models such as the one in Picture1.

Slicer processed the model as I inserted it and assembled it from two parts and then merged it into one model. (Picture2) The printer works without problems as long as both colors are contained in the layer. The problem appears when there is only one color left to print (Picture3). The printer continues to work according to the GCode instructions, but the extruder stops extruding the filament and the model is missing its top part in one color. (Picture4) But the UltiMaker Cura slicer does not show any defect (Picture2). I solved my case with Geeeetech support, but I was advised to use a different slicer software, because according to them, UltiMaker Cura is not suitable for multi-color printing.

Can someone help me solve this error?

[MariMakes 203]

Hey @klickon,

 

Welcome to the UltiMaker Community 🎉
This looks like a problem with underextrusion. It almost seems like the flow of the layer doesn't start.
Have you considered adding a small block next to your primetower as long as your model to make sure that the primetower is longer and the material is primed? I've seen other people use that. 

[klickon 0]

Hi MariMakes,

 

First of all, thank you for welcoming me to the UltiMaker forum community. 

 

Your solution to the two-color printing problem I described occurred to me as well. I have already tried this procedure and it works. I just don't understand why it is not possible to implement this option directly in the software. For instance, the ability to choose the height of the primetower. The process described above increases the filament consumption and also increases the printing time. I tried printing several two-color 3D models and the result was always the same. The printer will no longer print the last layer in a different color.

[GregValiant 1,344]

@klickon post one of the "bad" gcode files.  Maybe something odd is going on at the last tool change.

 

The last change shouldn't be any different than the rest.  Same retraction and prime amounts as happened earlier in the print.

 

 

 

[Danthelad 0]

I have exactly the same problem now but didn't have it when first using the printer. It has only become apparent recently. I found out that in the g code for printing any model where the last layer of a support has finished and it has to swap to T0 (from whichever extruder is used for the support), there is a line of code in there before the switch, that turns off the hot end heat value, so that neither extruder will move because it cannot force the filament through the now cold hot end. If that line (M104 S0) is removed, printing continues as normal. That line tells the hot end to be set to 0 degrees. I had to search all the way through the actual g code text file to find the problem line. I would like to know why it has only just started to get inserted by the slicer software? Do I have to alter every g code file that changes from one extruder to another when using a prime tower that finishes before the model is completed? Is it a bug?

[GregValiant 1,344]

That line is added for conventional dual hotend printers.  At the last tool change the unused tool is shut off.  It does cause a problem for "multiple-in-one-out" hot ends like some of the Geeetech printers.

I see that neither the Geeetech Base Dual Extruder definition nor the Mizar M definition file have overrides that address the problem and if your printer is a 2-in-1 or 3-in-one-out, then the author missed a trick.

 

If your printer is equipped with a mixing hot end then:

If you haven't done so, go to the Cura MarketPlace and load the "Printer Settings" plugin.

Restart Cura.

Printer Settings will appear as the bottom settings group.

Find "Extruders share heater" and "Extruders share nozzle".

Enable both of those and the problem should go away.