Extended Multi-Colour Filament

I found this filament model very interesting to experiment with so I made some of my own modifications that maximise its potential for a Prusa i3 and allow larger prints to be made on a single run.

Main adjustments made to the OpenSCAD file were:

• 38 turns, 210mm outer diameter
• Spacing changed from 0.5 to 0.3
• $fn parameter added and set to 120

I find that these filaments give the best results when printed in strongly contrasting hues such as green and red, orange and blue, etc. But they can also be good for a subtle gradient of tones when printed with similar colours.

Recommended for direct-drive print heads only.

Printing Notes

See the included .3mf file(s) for complete settings.

General guidelines:

• Rotate model so that the square brims are in line with the X axis
• No skirt or brim
• 0.2mm layer height
• 110% flow rate (adjust this in Printer Settings/Custom Gcode/Start Gcode - change last command line to “M221 S110”)
• Set Seam Position to “Nearest”
• Setting perimeters a little thicker can reduce print time considerably - best results achieved with Arachne perimeter generator
  • 0.4mm nozzle: Aim for 3 extrusions across widest layers in preview
  • 0.6mm nozzle: Aim for 2 extrusions across widest layers in preview
• For two colours, set colour change at layer 5
• For three colours, set colour changes at layers 4 and 6
• Set Gcode resolution slightly lower (such as around 0.02) as this can avoid adding too many movement steps.

For a stock i3 with a V6 hotend, a speed of 65mm/s works well for both perimeters and external perimeters, but a little higher may be possible. Try a nozzle temperature about 5° hotter than usual as the temp can drop quickly on the second layer as it speeds up. Alternatively use Pressure Equalizer to ramp up the print speed gradually.

If you want a different weighting to the colours, then bear in mind that the middle layers are wider and therefore have more mass, so whatever colour(s) you have near the middle layers are going to come out more in the print it's used for.

Equally good results can be achieved with PLA or PETG.

Storage and Usage

The best way of storing these filaments is on a piece of stiff card in a resealable plastic bag or an A4 binder sleeve. Two can be stored flat on opposite sides this way.

Try not to store them loose with each other as they can get tangled very easily.

They can also be wound onto an empty spool - start from the outer end with the wide radius, and wind it on fairly tightly. The orientation should be easy to keep straight and the curled inner end will hold down by itself once finished.

If printing with a loose coil, hang on a spool holder (or improvised rail) with stops at each end to help keep the colour orientation straight and to make sure it doesn't fall off.

Setting the flow rate to 100% usually makes for a better result than the stock 95%.

If feeding in a tightly coiled end, gently bending it straighter can help to keep it from snagging the rim of the PTFE tube under the gears.

Small coil ends can be kept aside and combined to make yet more multi-colour, multi-orientation prints by feeding the next coil into the extruder as the tail of the previous disappears in. Keep holding it in there gently until the gears grip the filament.