MRRF: Innovating Extruders And Dissolvable Filament


Do you think depositing molten plastic on a 3D printer is as easy as pushing plastic filaments out of a hot pipe? It’s not, and anyone who had a 3D printer in 2009 would tell you as such. There were hobbed bolts that broke the plastic into a sticky paste, extremely large x-wagons that made everything shaky, and nothing worked as well as it does today.

Technology is advancing, and at this year’s Midwest RepRap Festival, people showed off the latest advances in pushing plastic and something that hasn’t found much use – detachable filaments.

Bondtech VT extruder

When we saw the Bondtech extruder at the last MRRF, it was a device that could push a lot of filament very hard; The promise of two knurled or planed gears pushing the filament through a hot end was very interesting. Here is a video showing the Bondtech extruder pulling filament with 20 kilos of force.

This year, [Martin] was back in Indiana showing off its latest version of the Bondtech extruder. While with the old Bondtech extruder you had to send commands to the stepper motor to change the filament, the new QR (quick release) version contains a lever to lock the filament.

While this isn’t a big change to the Bondtech extruder, it does make a great extruder even better. There were a number of RepRaps rocking the Bondtech at MRRF, and [Martin] has put together a very nice product.

The improved wades

Wade’s geared extruder has always been, or at least since 2010, the standard low-end extruder for RepRaps and other DIY 3D printers. It’s simple – just a motor mount, two gears, a hobbed bolt, and a couple of springs and bolts. It’s so popular that there’s a digital archeology project on Wade’s extruder.

Mini wadesThat said, this extruder is heavy, and if you mount it on a moving cart you will quickly create a wobblebot. The E3D guys were at MRRF this year and showed off some new advancements including a miniaturized calf that they use in their new BigBox 3D printer.

The new extruder is exactly what you would expect from an injection molded plastic gear drive extruder. A tiny motor is screwed onto the extruder, and a gear system drives a curved, knurled or otherwise modified shaft.

The E3D folks get this right and go so far as to look at the hobbed driver’s tooth profile. This reduces the pressure required to hold the filament in place and gives this extruder exceptional efficiency. At MRRF, E3D powered this extruder with a NEMA 17 motor with pancakes. Typically, these thin motors are unsuitable for 3D printing applications because they lack the torque needed to push the filament or move an axis. E3D’s extruder doesn’t need a big motor, and besides being a little warm, this extruder and motor performed as a champion.

Dissolvable filament

Video LAN Client, an example of the dual extrusion capabilities of E3DVideo LAN Client, an example of the dual extrusion capabilities of E3D

Dissolvable filament, which is used as a carrier material in RepRaps and other 3D printers, has been around for some time. Makerbot launched a line of soluble PVA in 2011, but somehow the idea of ​​extruding two types of filament and dissolving one when the print was done never really came up. We will never know.

Since E3D has a few different extruders designed specifically for double extrusion, it only makes sense that they include soluble filaments in their product range. It is also not a pure PVA plastic. E3D has developed a new PVA-based filament that also contains other water-soluble materials, such as the plastic gel-cap medications it is made from. They call this material scaffolding, and from the prints they had on display, it works really well.

A problem with soluble filaments is how to remove the carrier material. If you are using HIPS as a carrier material, you can dissolve it with limonene. However, this means that you will need to remove the amount of dissolved plastic and toxic chemicals that have been created. PVA is water-soluble, as are all other components of the framework material. The best way to dissolve the material on one print is to put it in a dishwasher.

While putting the scaffolding material in the dishwasher is not yet recommended – E3D is still working to certify the plastic as safe enough to wash off a drain – it’s the best we’ve got of in the last two or three years have seen soluble filaments. The resulting prints look amazing, and from what we’ve seen, two extruders could be a necessity in a few years.

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