Forget about printing clay, use this to print PLA to make master molds, templates, cutters, tools, parts, mold spouts, mock-ups.
The rear of a partially assembled RepRap 3D printer
In this printer (which is being assembled) the printhead moves along two stainless steel rods (for the x-axis). Its position is controlled by the front top stepper motor (which has a gear through which runs a rubber belt attached to the printhead. The two lower stepper motors with worm gears attached to their shafts control the vertical z-axis position of the printhead assembly. Since the computer controls these motors it can move the head to any position on the x or z axis. Vertical z-movement is slower and more precise since it determines the thickness of each slice to be printed.
The controller board on a common RepRap 3D printer
This board is an "Arduino computer", a standard device around which a worldwide community of gadget-building enthusiasts has grown. It has also become standard on RepRap printers. This version has many connectors, they connect to stepper-motors (that control the X, Y, Z axis and the feeding of the filament through the printhead), to switches and sensors for the heating element and fans on the printhead and to sensors and switches for the heated bed. This board runs open source software that can read a gcode file (which defines the movements of the print head for each layer). It uses the Z-motor to move up for each new layer, the X and Y motors to control head movement for the layer and the filament-feed motor to control the extrusion.
The movable printing bed on a common 3D RepRap printer
These do-it-yourself kits are good to learn how the printers work (every part is clearly visible). The printhead slides (on bushings) along two horizontal stainless rods, a gear-belt driven by a stepper motor on the far left controls its left-right position along the X-Axis. Two motors on the lower left and right have vertical worm-gears that turn to move the whole printing mechanism up and down (along the Z-axis). Objects are printed on a platform that moves forward and backward (along the Y-axis). Like the print-head, the bed is attached to bushings that run along stainless steel rods running front-to-back, a rubber belt that runs around a pulley in the front and around a gear on a Y-Stepper motor at the back controls the bed position. The bed is heated, this keeps the printed piece from warping and loosening during printing.
The printhead of a common RepRap 3D printer
The assembly has a powerful electric stepper-motor with attached to a gear assembly that pulls the filament in through a hole in the top. It forces the filament down through a heated nozzle. PLA is a common filament type, it requires the nozzle be at 215C to extrude well. The brass nozzle puts out a 0.45mm wide extrusion (it is mounted to the bottom of a small aluminum block at the bottom). The nozzle has a heat sensor and its own cooling fan (enabling the controller to precisely maintain nozzle temperature). An additional fan and heatsink (on the left side) keep the motor and filament feed area cool. The entire head assembly is pulled left and right along stainless steel rods by a gear-belt controlled by the X-axis motor. Inserting filament can be tricky in machines like this. The best strategy is pre-heating the nozzle, pressing release level (to enable free filament movement) and then pushing the filament to feed it manually through the nozzle, then pulling it out suddenly. To reload, cut it to a point (using scissors), configure the printer to preheat the nozzle to 215C, then feed it down through until it extrudes.
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