Paper extruder 2a

myminifactory

A miniature paper-making machine creates a 10mm strip of paper pulp by rolling it around and around to build up a three-dimensional object. The extruder part takes in water and pulp, sucks out water and air, and rolls the paper pulp layer onto the surface. This is a true mini-factory; it's mine (and shared with you), it's small (or even tiny) and it certainly makes paper. This design has NOT BEEN TESTED yet. It's published partly to ensure I don't lose the files (as I did with an earlier iteration), and partly because there's a competition that has a machine category. Paper-making machines can be huge (workers can use bicycles to ride from one end to the other); this machine is about 72mm tall and about 32 x 21 mm cross-section. For our paper extruder, the suspension of paper fibres comes in through a tube (3mm ID) into the central hole, through a 2mm nozzle and onto the sieve, which is a wheel with a mesh 'tread'. As the extruder moves forward, the wheel presses the paper pulp onto the surface, where the pulp sticks (hopefully). We don't want the water to just flow over where we've just rolled out a thin layer of paper pulp, so we use active suction on the inside of the rolling sieve to remove the water from the inside of the wheel, and it drags a lot of air as well. At the top, there are four tubes to ensure plenty of flow of air and water out of the extruder head. The designed operation of the rolling sieve wheel is like a caster wheel, so that the wheel skids a bit going around corners, but still continues to roll along in the direction of movement; but it must have a turning axis about the vertical. This means that there has to be a 'fixed' part at the top for all the tubes, and part that rotates about the vertical axis whilst still allowing for flow of suspension of paper fibres in, and the flows of water and air out. The wheel has to freely roll based on contact with the surface, not the extruder itself. Even though this design hasn't been tested yet, I've been working on making a 3D printer that can print room-sized or house-sized objects (see https://hackaday.io/project/13420-rigtigs-big-3d-printer). I wanted something that could be recycled easily, wasn't too heavy, was cheap (like free) and yet be made quite large. In a presentation at a makers' place several years ago, one audience member said he could provide 10 tonnes of waste paper to me every week, delivery in metro area free (but I did respectfully decline his generous offer). I am still using what comes through my letterbox!!