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Multi-Color Prints with Dual Extruders

Multi-Color Prints with Dual Extruders

Earlier this year when I first got my Felix 2.0 printer I was eager to try the dual extrusion feature -- after all that was one of the reasons I bought this printer in the first place.  The prospect of being able to print in multiple colors or even possibly with dissolvable support material, such as HIPS was intriguing!  

It turned out that dual extrusion printing was still very much in its infancy. A lot of slicing software simply didn't support more than one extruder and others, such as KISSlicer, offered only using the second extruder for support material, but not for "true" multi-material prints.  I tried a few prints with a different support material, but never got a successful print.

Recently I stumbled across the announcement that Jonathan Drummer had started development on KISSlicer again (find the full announcement at toybuilderlabs.com). The latest 1.4 version is actually a preview of 1.5 and now allows for up to 4 extruders and true multi-material prints.  (Note that I own the PRO version and some or all of the dual extrusion may not be working unless you purchase a key.

Object & Material

The object we'll be printing here with dual extrusion is a miniature filament spool with our Cubicity logo on top of it.  There is a practical purpose to this -- we plan on handing this out together with our promotional offer at the upcoming World Maker Faire in New York. That is, of course, if we can get the multi-color print to work.

The first version of the spool measured 25mm in diameter and about 10.7mm. We increased the size to 28.5mm x 13mm as it looked a little smallish at first.

All the prints were done with Voltivo ExcelFil PLA 1.75mm: Coal Black, Cherry Red, Leafy Green and Bling Gold.

 

First Attempt

After downloading the latest version of KISSlicer and good starting profiles from the Felix Printers forum. Without much change, we got fairly promising results:

Multi-Material Print - First Attempt

Multi-Material Print - First Attempt - Profile 1

Multi-Material Print - First Attempt - Profile 2

You'll notice some general imperfections, which could be due to the fact that we printed this in draft quality with a 0.25mm layer height (subsequent prints are all done with 0.2mm layers).  Most noticeably though, we see some significant spots of the wrong color. This was because the non-active extruder kept oozing filament -- the "keep warm" temperature was too high at 175° C.

Improving

For the next attempt we used a "High Qality (200 micron)" profile in KISSlicer and reduced the temperature of the inactive nozzle to 160° C.  It did take more time to heat-up and cool down the extruders for each color change, but it didn't affect the overall print time too much.  The bigger spool took about 35 minutes and while we didn't time this, only about 3-4 minutes are probably lost during extruder switches.  However, this can become a consideration if you have a considerable number of extruder switches. (One way to minimize this impact, especially when printing smaller objects, is to print multiple objects at once.)

Multi-Material - Second Attempt Improved

We can see that the result is much improved.  The inactive extruder ultimately does stop oozing, however there are still a few spots of black in the first layers of green. We also notice a slight seam and the overhang is not perfect yet; neither of which is related to multi-material printing, but we'll address that with our final sets of prints.

Final Result

For our printer and filament combination it turned out that a warming temperature of 150° C was perfect.  It cooled the extruder down enough to stop oozing and it also took long enough that it had stopped when the print resumed.  Note that we highly recommend printing a prime pillar.  It helps to ensure that filament starts flowing after the extruder had been inactive and it takes off the little bump of filament off the extruder that was just turned off.

We made a couple other adjustments to improve the print quality as well:

seam hiding with 180° jitter
loops from inside to perimeter (to improve the overhang)

Optimizing our extrusion width, wall thickness and infill parameters added a few extra minutes so that a spool now took 44 minutes to print. The result however is quite impressing.

Multi-Material - Final - 01 - Red

Multi-Material - Final - 02 - Multiple

Multi-Material - Final - 05 - Red Finger

Multi-Material - Final - 03 - Red profile

Multi-Material - Final - 04 - Green

Multi-Material - Final - 06 - finger Red

 

What's Next

It's worth noting that we only changed colors along the z-axis, i.e. each layer was printed with a single extruder.  We imagine that printing different colors within layers is yet another challenge and we'll be sure to write about it once we try.

We will also shortly post a detailed description of the process to do these dual-material prints, from initial CAD design to cutting the model, slicing and printing! Check back here or follow @CUBICITY3D on Twitter to get notified when we do.


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