2.5 Multi-colour printing
Module 2 · Lesson 5 of 10 · about 4 min
Multi-colour printing is normally done with the four-slot AMS 2 Pro. On an X2D that means the left nozzle, and on an H2S its only nozzle. Every colour change then means purging (also called flushing) the old colour out of the nozzle, and that purge is where the filament goes. Most of this section is about wasting less of it.
Giving colours to your model
There are two ways to tell Bambu Studio which parts get which colour.
A colour per object or part
If you designed the model as separate bodies, for example a base and the lettering on it, you don't need to paint anything. Select all the files and import them in one go. When Bambu Studio asks whether to load them as a single object with multiple parts, choose Yes to keep them together, or No for separate objects. Then choose a filament for each object or part in the object list on the left. This gives the cleanest colour borders, because they follow your own geometry. It is worth planning for when you design a part.
Bambu Studio's object list with a model made of several parts: Body1 on filament 1, the others on filament 2
Painting
If the model is one solid body, paint the colours onto it.
Bambu Studio's colour-painting tool, with Fill selected, Edge detection on and the Smart fill angle slider, and the painted model
To paint, select the model and press N, or click the paint-bucket icon.
Fill tool: one click colours a whole face or area. Turn on Edge detection and use the Smart Fill Angle slider to control how far the colour spreads onto neighbouring faces. Works very well on geometric shapes.
Circle tool: a freehand brush. The pen-size slider sets the brush size. Use it for detail.
When you colour raised text, remember to colour the sides of the letters too.
Where the waste comes from
Each filament change has four steps: flush the old material out, wipe the nozzle, prime it on the prime tower, then print. Two things decide how much filament is wasted:
Flushing volume, which mostly depends on the colours. Going from dark to light needs a big flush, and light to dark needs much less.
The number of filament changes, which matters most. On a single nozzle, each layer costs (number of filaments on that layer − 1) changes.
Ways to waste less
Bambu Studio's Purging volumes for filament change dialog, with the Multiplier field marked
What to change | Effect |
|---|---|
Flushing multiplier (Project Filaments → Purging volumes) | The default is 1.00. Lowering it to 0.9 or 0.8 cuts every flush by 10–20 %. Too low and you get discoloured layers, so test it first. |
Flush into objects' support | On by default. The purge goes into support you throw away anyway. Needs the prime tower turned on. |
Flush into objects' infill | The purge is hidden inside the part. Be careful with light or see-through filament and thin walls, because it shows through. |
Flush into this object | Add a throwaway object to the plate, and turn on this setting for it, so it takes the purge. In Bambu's example, this cut a cube's waste from about 70 g to under 1 g. |
Layer height | In another of Bambu's examples, a four-colour cube: 153 changes and 104 g wasted at 0.2 mm, but 111 changes and 76 g at 0.28 mm. That is about 27 % less. |
Orientation | Laying a part down so the colours stop alternating every layer can cut waste by 80 %. Turning it the wrong way can make it 24 times worse. Slice both ways and compare. |
Batching | If a layer already has those colours, extra parts in the same colours cost nothing more. Nine identical cubes waste the same as one. |
One colour on the right nozzle (X2D) | You may load one colour in the AMS HT. It prints from its own nozzle, so changes to and from it need far less flushing. But the right nozzle prints slower and a little rougher, which can make the print noticeably longer. Use it for a small, less visible colour, and check Bambu's compatibility guide first (2.4 Support material, and the X2D's second nozzle). |
The prime tower has to be as tall as the highest layer with a colour change. In Bambu's example, turning a model so its colour changes were near the bottom instead of the top shrank the prime tower from about 15 g to under 6 g.
The figures in this section are Bambu Lab's own tests, quoted to show how big the effect can be. Your results will be different. Slice it both ways and compare. That takes a minute, and it is the real skill here.