Mulitcolour printing with one hotend

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Multicolour printing with one hotend using hardware

Multicolour printing with one hotend using Slic3r

Multicolour printing with one hotend using Slic3r requires manually changing the filament on each layer that more than one colour exists, for this reason it is most suitable for achieving multicolour prints where only a small number of layers are multicolour e.g Inlay.

Slic3r Printer Settings

Rather than modify your default settings, Slic3r allows you to create profiles to achieve different functionality.

Printer settings

Open Slic3r

Select Printer Settings

Click the Save icon next to the printer name

Enter a new name of Multicolour ….. whatever you want to call it, then click OK

You will now have a new Printer setting alongside the original ones that Prusa supplies

Extruder settings

On the General | Capabilities Section is a heading Extruders

Increase the number of extruders as per how many colours you may want to print with on a single print based on the number of filament changes. You can have more extruders than you are going to use, 6 extruders is fine if only printing in 2 colours, Slic3r ignores the excess extruders.

Once modified you will see that the left hand Viewing Pane also now has 6 extruders

By default, if you select and of these extruders, you should not have to adjust any default settings from your normal printing.

Tool change G-Code

Now set a custom G-Code that runs for what Slic3r thinks is a tool change. Select Custom G-Code on the left hand Pane and then scroll down on the right hand side to Tool Change G-Code.

In the Tool Change G-Code box, enter M600 and click the save next to your printer settings name again to save all the changes made.

Then click OK.

Parts design

The aim of this step is to have a separate exported STL file for each part of your print that will be a different colour. This method of multimaterial 3D printing is best used for a very small number of multimaterial layers. If yu are producing inlay you do not need the text height to be more than two layers. If you are going to print at .20 then only make your inlay .4 deep and when sliced it will become 2 layers. If you are printing at .15, then make the inlay .30 and so on.

Above is a blank LCD cover, I have selected the normal text and extruded it level to the front face so it is now blank and ready to use. In front of the model, create the text you want to display on the cover, here I use Arial Rounded MT Bold in Bold and Size 15mm.

Extrude the text to make it an object by .4mm

Position the new Text object onto the face of the LCD cover

The text is now proud of the LCD cover and needs to be sunk into the body. As we know the text is .4mm high from when we extruded it, we need to lower it by .4mm

The text is now sunk into the object. You could have created the text directly on the face of the cover and various other ways to save time.

Both objects should now be rotated into the printing position before exporting them.

Export the object (text only) as an stl and labelled up as just text.stl Now you need to subtract the Text from the LCD cover to leave an indent. All software can do this, on 123D it is just subtract. The LCD cover should end up looking the same but with a recess of your Text. The picture below is the part that will be touching the bed.

Now extract just the LCD cover as an STL, labelled up as LCD Cover or similar.

You now have two STL’S, one for text and one for the cover. The way above doesn’t move them about the design surface and as such means that when you go to print them, they will be in the same position.

Setting up the Print in Slic3r

You now have two parts of this print, if you are printing anything with more colours then you would have more STL’s, the same process works for this, you just continue the changes as suggested.

Open SLic3r

On the right hand side, click the drop down arrow next to Printer selection, select your newly created profile.

You will now see more filament options than before because you configured multiple extruders. At this point it’s worth noting that whilst it is possible to use different types of filament, it is not advisable. You can mix types of the same type though (different manufacturers).

In this example we are using 2 colours and as such only need to adjust the top two filament types.

Above we have selected White as the first type and Brown for the second.

In a two colour print such as the LCD cover, if you place the text on first, Slic3r will print the first layer of the text, then the first layer of the LCD cover, then the second layer of the text and then the rest of the LCD cover. Changing between these layers requires a filament change. So if you place the LCD cover first and then the Text, it will print the first layer of the LCD cover, then will print 2 layers of the text and then the rest of the LCD cover. This means you will only have 2 filament changes (remember that you chose a height of the text as .4mm

Add the LCD cover using the Add button.

Now click on Settings, this is where we will now add the second part

Select under Parts the LCD Cover stl file and under extruder, change it from default to 1

Now click on Load Part to load the text Choose your text file and this will load although may not be instantly visible on the viewing screen Select your text STL under the parts selection, change this extruder to 2

Click OK

Back to the main window, if you rotate the bed to view underneath, you will see the Text is there as a second colour now and in the right place. The two parts are interconnected so if you rotate one, then both will rotate so you can now move it around the bed to where you want.

Make sure you set your print settings to match the height of your layers and you can now slice and export the G-code.


Once it has finished one layer, it will move the head to the front right of the bed and unload the filament. Load and press the button, this can often take multiple attempts for the filament to be clear.

You will be asked to confirm that the filament has loaded correctly, this is the trickiest part. It has already ejected a spiral of filament, do not push this off until after you have clicked ok, filament loaded ok. Once you do, it will still push out a little more filament before the hotend moves back to the print. It is helpful to keep spatula behind the hotend (in between the print and the hotend) until this last bit has been put out, As the hot end starts to move I use the spatula to make sure that no filament is being dragged back to the print.