Servo - January 2016

During the initial startup of the software, you must pick your printer (e.g., LulzBot Mini), as well as install drivers for Windows installations. Then, just plug the included USB cable into your computer, attach the included power cord into a three-prong outlet (I used an IsoBar isolated, surge suppressor, multi-connector power strip), flick the power switch ON, then launch Cura. Within a few moments, the rocktopus 3D model will automatically load into Cura. There is a dead-simple six-step procedure in the LulzBot Mini Quick Start guide that will lead you through the removal of the leftover HIPS filament (that’s the filament used by Aleph Objects for printing the test octopus for your printer), the insertion of the one meter test filament, and the printing of the rocktopus 3D model. During the start of the printing process for every 3D model, the LulzBot Mini performs a regiment of tests, checks, and controls that will quickly inspire you with the incredible amount of mechanical precision and engineering robustness that has been designed into this printer. First of all, the extruder tool head assembly is raised to the maximum height of the Z axis (see Figure 4) for preliminary heating. At this same time, the bed is withdrawn to the furthest back extent of the Y axis.

Once the hot end reaches approximately 160 degrees Celsius (that is about 80 degrees shy of the final printing temperature of 240 degrees Celsius for HIPS), the extruder retracts the filament from the hot end and the entire tool head assembly is lowered to the back area of the bed where a dedicated “wiping pad” is installed as shown in Figure 5.

This thick heat-resistant user-replaceable material is actually deeply gouged with the nozzle for clearing all filament residue from the hot end. It’s a simple and effective process that is supported with six extra pads that are included with the printer.

Why is so much effort expended for cleaning the nozzle before every print? Because the next step in the The Mini’s technique is an impressive technological wonder featuring a gentle double kiss of large electrically-conductive washers fixed to the four corners of the print bed (see Figure 6).

Now that the printer has been tested and we’ve checked its electrical and mechanical operation, one final print control is performed. Having precisely established the actual print bed height, the extruder tool head heats up to printing temperature, lowers to the print bed, begins to draw filament into the hot end, and establishes a simple outline skirt around the upcoming print.

This final control element does two things right: It ensures that the filament is extruding consistently from the nozzle, and it creates a simple moat or boundary around the print that helps the upcoming