3D Printing Different Colors with a Single Extruder

Let’s be honest, multi-extruder 3D printers don’t work the greatest — even MakerBot decided to get rid of the feature in their latest line of printers. So what are you going to do when you want to print a multi-colored object with your trusty single extruder? Pause the print like a savage and exchange the filament? No, no, it’s much easier than that — well, you’re still going to have to switch the filament.

[Jan Henrik] has put together a simple script in OpenScad to split up 3D files into layers in order to facilitate printing in multiple colors (or even materials). You load in the file, tell it the print height you want to do, export, convert to G-Code, print, rinse, repeat. In between the layers you have time to purge the extruder, remove any excess skirt or support material, and then hit print again. Quite a bit easier than hitting pause and jogging the extruder out of the way (while avoiding plastic dribble coming out of your extruder!).

Meanwhile if your prints get interrupted — or fail a lot — you might be interested in this project by a group of MIT researchers. It’s an add-on for 3D printers that uses a laser scanner to evaluate how much of the part was printed, allowing you to restart a print that failed!

Making T-Glase Crystal Clear

There are 3D printing filaments out there with a lot of interesting properties. Whether it’s the sanded-down MDF feel you get from Laywood, the stretchy and squishy but somehow indestructible feel of Ninjaflex, or just regular ‘ol PLA, there’s a filament out there for just about any use. Even optically clear printed objects. Yes, you can now do some post-processing on printed parts to make T-glase crystal clear.

The big advance allowing translucent parts to be made clear is a new product from Smooth-On that’s meant to be a protective and smoothing coating for 3D printed objects. With PLA, ABS, and powder printed parts, this coating turns objects shiny and smooth. Strangely – and I don’t think anyone planned this – it also has the same index of refraction as T-glase. This means coating an object printed with T-glase will render the layers invisible, smooth out the tiny bumps in the print, and turn a single-walled object clear.

There is a special technique to making clear objects with T-glase. The walls of the print must be a single layer. You’ll also want a perfect layer height on your print – you’re looking for cylindrical layers, not a nozzle that squirts out to the side.

The coating for the pictures above was applied on a makeshift lathe built out of an electric drill and a sanding pad. This gave the coating a nice, even layer until it dried. After a few tests, it was determined lenses could be printed with this technique. It might not be good enough for 3D printed eyeglasses, but it’s more than sufficient for creating windows for a model, portholes for an underwater ROV, or anything else where you want nothing but light inside an enclosure.

Custom Filaments With A Filastruder

A while ago, when 3D printing was the new hotness, a few people looked around and said, ‘our printers are open source, why can’t we just build the machines that make our 3D printing filament?’ There was a $40,000 prize for the first person to build an open source filament extruder, resulting in a few filament fabrication machines being released into the wild. [Rupin] over in the Mumbi hackerspace has one of these filament extruders – a Filastruder – and decided to take a look at what it could do.

The experimentations began with a few kilograms of ABS pellets he found at the market, with bags of red, blue, green, and white masterbatch pellets showing up at the Hackerspace. Experimenting with these pellets, [Rupin] was able to create some very nice looking filament that printed well and changed color over the course of a print.

There were a limitations of the process, though: the filastruder has a long melt zone, so colors will invariably mix. If you’re thinking about doing a red to blue transition with filament created on a Filastruder, you’ll end up with a filament with a little bit of red, a little bit of blue, and a lot of a weird purple color. The time to create this filament is also incredibly long; over the course of two days, [Rupin] was able to make about half a kilo of filament.

Still, the results look fantastic, and now that [Rupin] has a source for masterbatch and ABS pellets, he’s able to have a steady supply of custom color filament at the hackerspace.

Coloring 3D Prints With Sharpies


Printing objects in full color easily is one of the paramount goals of the ‘squirting plastic’ 3D printer scene, and so far all experiments have relied on multiple colors of filament, and sometimes multiple extruders. This, of course, requires a stock of different colored filaments, but [Mathew Beebe] has a different idea: why not dye a natural colored filament just before it’s fed into a printer? Following his intuition, [Mathew] is doing some experiments with the common Sharpie marker, and the resulting prints look much better than you would expect.

The basic procedure or this technique is to drill a hole in the butt end of the Sharpie, pull out the felt in the tip, and feed a length of filament through the marker before it goes into the extruder. The filament is dyed with the Sharpie ink, and the resulting print retains the color of the marker.

Despite the simplicity of the technique, the results are astonishing. An off-white ‘natural’ filament is easily transformed into any one of the colors found in Sharpies.

Besides the common Sharpie, there’s a slightly more interesting application  of this technique of coloring 3D printer filament; as anyone who has ever been in a dorm room with a blacklight knows, you can use the dye inside a common highlighter to make some wicked cool UV-sensitive liquor bottles. Whether the ‘Sharpie technique’ works with highlighters or other markers is as yet unknown, but it does deserve at least a little experimentation.

Video below.

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Awww Shoot! My Spool Doesn’t Fit My Holder


The great thing about standards is that there are so many to choose from. Filament spools certainly do not deviate far from this sarcastic saying. So what are we 3D Printer folks to do? Here are a couple completely different DIY options:

[Mark] made a spool holder that can accept 2 different width spools. This design uses skate bearings to support the spool on two points at each end. There are 3 sets of bearing blocks to accommodate the 2 different width spools. When either size spool is installed, one of the bearing block sets goes unused.

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Recycling Plastic With Liquid Nitrogen


Recycling 3D printer filament isn’t a new idea, and in fact there are quite a few devices out there that will take chunks ABS, PLA, or just about any other thermoplastic and turn them into printer filament. The problem comes when someone mentions recycling plastic parts and turning them into filament ready to be used again. Plastics can only be recycled so many times, and there’s also the problem of grinding up your octopodes and companion cubes into something a filament extruder will accept.

The solution, it appears, is to freeze the plastic parts to be recycled before grinding them up. Chopping up plastic parts at room temperature imparts a lot of energy into the plastic before breaking. Freezing the parts to below their brittle transition temperature means the resulting chips will have clean cuts, something much more amenable to the mechanics of filament extruders.

The setup for this experiment consisted of cooling PLA plastic with liquid nitrogen and putting the frozen parts in a cheap, As Seen On TV blender. The resulting chips were smaller than the plastic pellets found in injection molding manufacturing plants, but will feed into the extruder well enough.

Liquid nitrogen might be overkill in this case; the goal is to cool the plastic down below its brittle transition temperature, which for most plastics is about -40° (420° R). Dry ice will do the job just as well, and is also available at most Walmarts.


The LATHON Dual Nozzle 3D Printer


Our friends at Freeside Atlanta have been keeping busy despite the city-stopping snowstorms they’ve been suffering recently. This time it’s a 3D printer with dual extrusion: the LATHON printer. [Nohtal] bought his first 3D printer only two years ago, but his experiences led him to build his own to overcome some of the issues he encountered with standard printers.

The LATHON keeps the bed stable and instead moves only the nozzles, using Bowden extrusion to reduce the weight on the moving parts. A key feature is the addition of a second nozzle, which usually limits the print area. The LATHON, however, maintains a 12″x9″x8″ build volume thanks to the Bowden extruders. [Nohtal] documents the majority of his build process on Freeside’s blog, including using a plastic from GE called Ultem 2300 for the print bed, and running the printer through its paces with a slew of materials: ABS, PLA, HIPS, Nylon, TPE, Wood, and Carbon Fiber. You can find more information on the Kickstarter page or at lathon.net

Check out some videos below!

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