- 1). Choose your materials. This example will assume that you will be creating your prototypes out of granulated sugar. This material does not allow for a great degree of resolution and is not particularly sturdy either, but its low cost and ease of acquisition will allow you to create very large models. If you would rather work with plastic pellets or with silicone, you can find out about the suitable modifications to the device in the resources area.
- 2). Build a wooden frame for your device. This version of the rapid prototyping machine uses a hot air gun to selectively fuse together a layer of sugar, which is lowered and then covered with more granulated sugar that is fused again. By repeating this procedure and accumulating sufficient fused layers, complex 3D shapes can be created. The crucial component for this procedure is a wooden frame sturdy enough to support the weight of multiple pounds of granulated sugar, with a moving table that can be lowered with a good amount of precision without spilling the material. Use the automotive jack, connected to the large servo motor, to raise and lower the table, and line the inner side of the device with canvas to prevent spillage.
- 3). Assemble the printing/heating head. Your goal is to create an air gun hot enough and precise enough to selectively melt the sugar in the topmost layer without affecting the levels below it. This can be done by forcing the output of an aquarium air pump through fine refrigerator tubing wrapped around a cartridge heater. You can test the heat and precision of the assembly by using it to write on a slice of bread. If the head can toast the bread with enough control to make well defined characters, it will have the precision required for selective melting.
- 4). Assemble the control mechanism for the printing head. In order to print in 3D you need control over the Z axis, provided by the jack below the table, and over the X and Y axes. Those two last degrees of freedom will be provided by the carriage mechanisms that you took out of the two scavenged printers. In the candyfab implementation, one of the belt driven carriages is mounted to a rail that is itself propelled by the other carriage. The motors are controlled by means of a microserial servo controller, and this configuration allows for computer controlled movement of the heating head to any point of the topmost layer of the working volume. Your implementation can vary, depending on the particulars of the mechanisms available to you.
- 5). Use the 3D software to create a 3D design, and slice it into thin layers that can be printed with your device. There are many free tools that can be used for the modelling stage. POV-ray has been tested for this particular device, but you can use any other program as long as it has the capability to produce bitmaps representing slices of your model. Those bitmaps are to be taken as the input of the next layer of software, which will output instructions for the micro serial servo controller to relay to the printer carriage mechanism.
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