I initially built the Prusa i3 from a kit starting in December 2014.
The kit was purchased from a company called Semi-Utilitronics via the eMakerShop website. The kit cost just £399 plus £12 p&p. It arrived on 18th Dec 2014 packed in 2 pizza boxes (unused I hasten to add).
I checked the contents to ensure all the parts were present, which they were then went to the suppliers Facebook site for instructions. These were fairly basic, consisting of a series of pictures. Although this was helpful I also trawled the web for more detailed instructions. I found some good instructions for similar printers but the best place I discovered was the Reprap Wiki.
I have added links to the Reprap Wiki and manufacturers’ websites throughout the text where possible.
Suitably armed I set about building the y axis.
Y Axis Assembly
The y axis consists of the horizontal frame that supports the moveable print bed which is moved from front to back.
X Axis Assembly
The next step is to assemble the x axis. This moves horizontally from side to side and carries the extruder assembly.
Z Axis Assembly
The z axis is the vertical dimension. It allows the x axis to be raised and lowered moving the extruder assembly up and down. This axis is the slowest moving when printing is taking place as it only steps up when the next layer is to be printed.
Stepper Motor Installation
Four stepper motors are used on the printer frame to provide the 3-axis movement. One on each of the x and y axes and two on the z axis. The z axis needs two in order to ensure that the x axis is kept exactly parallel to the print bed.
Toothed Belt Installation
Toothed belts are used on the x and y axes only. They need to be fairly taut but not so much they restrict the movement.
The extruder is the business end of the printer. It consists of two main components:
The cold end is responsible for pushing the solid filament into the hot end at a controlled pace. In this printer it does this by means of a ‘hobbed bolt’. This is an M6 bolt that has grooves cut into the sides that digs into the filament and drives it into the hot end. A small idler wheel keeps the filament pressed against the hobbed bolt to ensure a constant pressure is maintained.
The hot end is essentially a heated metal tube that melts the filament which is forced out through a nozzle forming a thin stream which is laid down to make the print. The heating is done via a 12V heater cartridge. There is also a thermistor attached to the hot end in order to monitor and control the exact temperature. This printer uses a commercially available E3D V6 hot end. The hot end has a heat-break where it joins to the cold end to ensure the heat stays where it should. A small fan is constantly keeping this area cool to stop the heat creeping up and damaging the cold end which is made from plastic.
End-stops play a vital role in the operation of the printer. They ensure the control electronics can sense when the three axes are at one end of their travel. In this case they are set at the ends of the axes that represent zero. Some printers place them at the maximum travel positions and some even have them at both ends. This printer has a print area of 200mm(x) x 200mm(y) x 180mm(z). The control system is set up with the maximum dimensions ensuring it never goes beyond.
Heated Print Bed Installation
The print bed is heated to ensure that the part being printed sticks to the print surface. It contains a 12V heater and also a thermistor to ensure the temperature can be controlled.
The Power Supply that comes with the kit is a standard ATX style PSU as used in desktop PCs. This supplies the high currents needed by the printer at 5V and 12V at a very good price. It requires some modifications though before it can be used with the printer. The main issue is that these types of PSU are designed to be connected to a PC motherboard and will not suply any current until there is a certain electrical load on the various outputs. Also the usual PC on/off switch needs to be simulated by grounding one of the wires.
This is done by a combination of three components.
Arduino Mega 2560
This is a microcontroller which is programmed with the Marlin printer control firmware. Its role is to accept printing commands from a host program, in most cases this will be running on a PC and control the printer movement to produce the print. The outputs of the Arduino are too weak to control the printer so it needs some help.
This is a shield which is piggy-backed on the Arduino Mega 2560 board. It is controlled by the Arduino and gives the necessary power and control to actually control the movement and heating that the printer needs. The RAMPS also has four Pololu stepper motor drivers plugged into it. These provide the high powered control of the individual stepper motors. Five are supplied in the kit and there are room for five on the board; the fifth is only used if you have a dual extruder installed which we do not.
This is a piece of dedicated software that is flashed to the Arduino providing the actual control of the printer. It accepts commands from the host software running on the PC in the form of g-code and convert those into the required movement and control of the printer.