Nov 14, 2015 | By Benedict

Before getting to the nitty gritty of this article, we have to make one fact abundantly clear: We love 3D printers. Really, we can’t get enough of them. Seeing a nozzle whizzing back and forth at a precision of 100 microns is a thing of sheer beauty. Regardless, we must confess that sometimes, very occasionally, watching a 3D printer carry out a ten hour print can be a little boring. There, we said it. Sometimes, every now and then, we want to forget about precision and programming and just dive into a project head first, shooting plastic anywhere and everywhere. Companies like 3Doodler understand this desire. Those guys created a 3D printing pen, so that creators could build rough little 3D printed sketches on the fly, without even using a computer. What if we could have something like the 3Doodler, but on a larger scale? An enthusiastic Instructables user has built his own partially CNC milled, partially 3D printed hot plastic extruder. The machine can be used to manually extrude large numbers of plastic pellets, and looks incredible.

The maker of the hot plastic extruder, an Instructables user named [cheewee2000], sees the project as a work in progress, but has already posted videos of the 3D printed machine in action. The extruder works by taking plastic pellets and melting them down, before extruding the hot melted plastic through a custom shaped die. The plastic is extruded by a 1” wooden auger, which is driven by a stepper motor. Heat bands are used to get the plastic hot, with a thermistor used to measure the temperature of the molten material. A PID closes the loop and turns the heat bands on and off, to ensure a precise user-controlled temperature. The tip of the extruder features a mist cooling system, which uses compressed air to draw water to the tip. A spray of mist is then shot onto the hot plastic, making it cool down quickly. The extruder built by [cheewee2000] holds around 1.5lb of plastic pellets, allowing for some pretty sizeable creations, but a greater amount could be stored in a separate hopper connected by a tube.

Perhaps the coolest element of the 3D printed extruder is the way in which the user controls it. To control the flow of plastic, users can employ the device’s build in potentiometer, whilst there is a finger trigger and foot pedal to allow for different extruding styles. Now that’s what we’re talking about! Sometimes all we want to do is extrude hot plastic from a 3D printed gun.

Both the handle and hopper of the hot plastic extruder are made with a 3D printer. The grip of the handle consists of two 3D printed halves, screwed together with M6 screws, and there are two toggle switches to control forward and reverse motion of the auger. The hopper, in which the plastic pellets are stored and from which they are extruded, could theoretically be of any size. However, the maker’s design was made to fit the maximum build volume of his Ultimaker 2.

When the 3D printed parts and all other components have been assembled, the machine is a sight to behold. Users can either set the extruder on a workstation, moving a build platform manually against its nozzle, or—and we really love this—pick up the extruder like a gun and fire the hot plastic into shape. The creator has so far found polypropylene to be the easiest plastic to use, but users could and should experiment with other kinds. Check out the cool videos below to see the 3D printed extruder in action!



Posted in 3D Printer



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