Color by Number 3D Printing Style

Remember paint-by-number kits? Your canvas has outlines with numbered regions that you paint with correspondingly numbered paints. When you are done, you’ve recreated the Mona Lisa. [KurtH3] uses a similar technique to coax multicolor prints from his 3D printer.

The technique isn’t general purpose, but it still is an interesting way to add some color to your usually monochrome prints. The idea is simple: You find a paint-by-number layout (apparently, you can find them with a Google search). Use your favorite method to get the outline into a CAD program. [KurtH3] doesn’t really get into the details about this, but some CAD programs will directly import images. Others will require you to trace in Inkscape (or a similar program) and convert to a vector format like DXF that the 3D CAD program can import.

Here’s the trick: instead of extruding the 2D image as one piece, you extrude the numeric regions to slightly different heights. Say you wanted to print a red, white, and blue flag to a thickness of about 5mm and you use 0.2mm layers. You could extrude the white part to 5mm, for example. Then the red parts could be extruded to 5.2mm (one layer higher) and the blue parts to 5.4mm. You could extend the idea to do multiple layers, although that will increase the surface roughness.

[KurtH3] pauses the print at the end of the layers to change filament, but we would probably edit the sliced G-Code to put pauses in the right places (for example, Repetier Host lets you put @pause in your file). You could also use software to split the G-Code as we’ve previously covered.  The resulting print, using our example, would be white from the bottom up but would have thin red and blue layers over the top in the right places. The few hundred microns difference from the white surface to the other colors means you won’t get a perfectly smooth surface, but a few hundred microns shouldn’t be too noticeable.

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A Quick and Simple Filament Joiner for Multi-Color Prints

Filament splicer

[Malcolm] was having a grand time with his new 3D printer. He was getting tired of monochromatic prints, though. Not having a machine with multiple extruders, he went looking for a way to join pieces of filament. There were a few designs on Thingiverse, but they required milled parts that he didn’t have the tools to recreate. Rather than invest in a mill, [Malcolm] decided to build his own filament joiner. He started by raiding his wife’s hair care tools. His first test was a curling iron. It had the heat, but lacked a good surface to join the filament. [Malcolm’s] next test was a ceramic hair straightener, which he found to be the perfect tool.

The splicing process is simple. Start with a hot iron, then lay two pieces of filament on top of the short end of the iron. They soften quickly and melt together. [Malcolm’s] real trick is to slightly pull the joint once the two pieces have joined. Pulling causes the filament to stretch, slightly reducing the diameter of the joint. A thinner joint helps prevent extruder jams as the joint passes through. This method works great for PLA. We’d love to see if it works for ABS as well.

Click past the break for an example piece and for [Malcom’s] instructional video.

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