Assembling our new Prusa 3D Printer!

Check out how we put together our Prusa i3 MK3S 3D Printer Kit, which you can learn more about here.


The first step was to get the parts out of the packaging. The printer came neatly organized with a great full-color manual. Each box was for a different category of parts, such as “fasteners” or “plastic pieces.” The printer also came with gummy bears, which were intended to be consumed when instructed in the manual!

Y-Axis Assembly

Our next step was to build the Y-Axis assembly, which moves the build plate forward and backward. This starts with attaching metal extrusions to the main frame. Next is to add rails with linear bearings for the build plate to slide on. Lastly, we add the motor and the belt to move the build plate.

X and Z-Axis Assembly

The X-Axis assembly slides the extruder left and right over the build plate. This step was simple, and involved attaching a few bearings to the steel rods, sliding them into plastic holders, and adding a motor.

Next, the Z-Axis uses threaded rods to move the X-Axis and Extruder assembly up and down. Using two motors, one on each side, they screw and unscrew the threaded inserts to raise and lower the assembly.

Extruder Assembly

The extruder takes in plastic PLA filament, heats it to a specific temperature, and deposits it in the appropriate location. The assembly features a motor which drives a special gear to keep the filament flowing, a proximity sensor for calibration, and fans to keep the parts cool. The Prusa uses an interesting magnetic tension system against a steel ball to keep pressure on the filament to hold it in place. This assembly alone was over 50 pages and contained 66 individual steps.

Electronics Assembly

Next we had to attach the LCD display and rotary selector. This step was fairly simple as the display and button combo comes in a prepackaged circuit board, and only has to be installed in the plastic housing. After this we installed the heated bed and power supply into the frame.

The brains of the printer are called the “Einsy”, and controls the entire operation. This was attached to the frame in a plastic housing, and all of the wires (which are quite a few!) are run into this housing and connected to the board. The Prusa guide even advises how to route the cables in the most efficient manner.

Lastly, we installed the spool holder, and the printer was built!

Calibration and Printing

When the printer is first turned on, it requires a quick calibration, which takes about 15 minutes. There’s little to be done here, and the printer does the work itself. Once this is complete, we tried our first few test prints!

First Print