MRRF: Hot Ends, Extruders, Extremely Posh Brits, and Stoic Swedes

As far as locations for the Midwest RepRap Festival go, it’s not exactly ideal. This is a feature, not a bug, and it means only the cool people come out to the event. There were a few people travelling thousands of miles across an ocean, just to show off some cool things they built.

Two Colors, One Nozzle

[Sanjay] and [Josh] from E3D came all the way from merry olde England to show off a few of their wares. The star of their show was the Cyclops extruder, a dual-extrusion hot end that’s two input, one output. Yes, two colors can come out of one nozzle.


If you see a printer advertised as being dual extrusion, what you’re going to get is two extruders and two hot ends. This is the kludgy way to do things – the elegant solution is to make two colors come out of one nozzle.

The guys from E3D were showing off a few prints from their Cyclops nozzle that does just that, including a black and red poison dart frog, and a blue and white octopus. The prints looked amazing, and exactly what you would expect from a two-color print.

Rumor has it the development of the Cyclops involved extruding two colors, freezing the nozzle, and putting it in the mill just to see how the colors mixed. I didn’t see those pictures, but there’s a lot of work that went into this hot end.

The Power of Two Extruders

[Martin] of came to MRRF all the way from Sweden. He was there showing off his new extruder.

The extruder uses a normal stepper motor, but instead of the usual knurled or threaded feed wheel and bearing to push filament though, he’s using two counter-rotating feed wheels attached to a planetary gear system. That’s a lot of torque that doesn’t distort or strip the filament. When you consider all the weird filaments that are coming out – ninjaflex, and even 3D printable machinable wax filament, this is extremely interesting.

Even if your filament isn’t exactly 1.75 or 3mm in diameter, this setup will still reliably push plastic; there is a bolt that will move one of the feed wheels in and out 0.4mm.

[Martin] had a pair of his extruders hooked up to a strain gauge, and it’s strong enough to lift your printer off the table without stripping the filament. Here’s a video of that demo from the bondtech page.

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

Check out some videos below!

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Dual extruders in the space of one stepper motor

The new hotness in 3D printers is – and has been for a while – dual extrusion. With two extruders and the requisite filament supply, it’s possible to print objects in two colors or two different materials. There’s a problem with this setup, though: each extruder requires a separate motor, greatly reducing the print area should you want to print in two or more colors. [Carl] and [Brian] think they have the solution to this with their dual extruder that is powered by one stepper motor.

As you can see from the pic above, the idea is relatively simple. Two strands of filament are fed past one gear attached to a stepper motor. Each strand is moved into the hot end through two idler gears and side of the extruder feeds into the hot end is determined by the rotation of the motor. It’s really one of those, “why didn’t I think of that” ideas.

[Carl] and [Brian] are also offering a quad extruder, a dual-sized extruder able to pump four different filaments onto a printer bed. With this, we expect some people to experiment with CMYK (or CMYW) prints, truly turning any 3D printer into a machine that prints full color parts.

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