3D printing, getting popular for making usable objects, is the reverse of traditional machining where material is removed from a block by drilling, cutting, chiseling, etc for making objects. In 3D printing, an object is created by laying successive layers of material as per requirement. This article describes how you can assemble a simple 3D printer for yourself, like we did in EFY lab, and then make use of it. But before that, you should know some basics of 3D printing.
The process of printing 3D objects starts with making a virtual design of the object you want to create, using one of the supported computer aided design (CAD) software. A 3D scanner can also be used to copy an existing object. The scanner makes a 3D digital copy of an object and puts it into a 3D modeling program. This 3D model file is sliced into thousands of horizontal layers which are then printed by a 3D printer, layer by layer, creating the entire 3D object. 3D printers generally employ one of below-mentioned methods.
Fused deposition modeling (FDM)
This is the most popular method used in DIY type 3D printers. Here a plastic filament or wire is made to pass through an extrusion nozzle (Fig. 2). The nozzle tip is heated to melt the filament or wire. The nozzle can be moved in all three directions, precisely, using stepper motors. The object is produced by extruding melted material to form layers upon layers of the object. The material hardens immediately after extrusion from the nozzle. The process is also known as fused filament fabrication (FFF). The printer shown in Fig. 1 is an assembled FDM based 3D printer.
Selective laser sintering (SLS)
In this method high-power laser is used to fuse small particles of plastic, metal, ceramic or glass powder to form an object. The laser selectively scans and fuses the material layer by layer as per the 3D model design. Once a layer is completely printed, the bed is lowered by one layer thickness and new layer of fused material is applied. The process is repeated until all the fused layers have been laid. Fig. 3 shows an SLS system.
This method employs ultraviolet curable photopolymer resin and an ultraviolet laser to build the object’s layers. The laser beam scans a selective surface area of the resin to solidify it as per the 3D design model. Once a layer is printed, the platform descends by a distance equal to the thickness of a single layer. And the laser scans again to print the second layer. Fig. 4 shows and SLA system.
How to build a DIY 3D printer
The printer described here is the LM8UU Prusa Mendel 3D printer. The basics of building any FDM based DIY printer will be more or less the same. The printer has three major parts: electronics (and electrical), software and mechanics.
Fig. 5 shows the complete electronic and electrical system that runs a 3D printer. Sanguinolulu board is the heart of the whole system. It controls different stepper motors for moving the nozzle in X and Y directions, moving the heat bed in Z direction and extruding the material from the nozzle.
Fig. 6 shows the stepper motors used. The board senses extruder’s and bed’s temperature through thermistors. Endstops are used (like stoppers) by the printer to determine the boundaries. Fig. 7 shows an endstop.
The temperatures of nozzle and heat-bed can be monitored through software as explained in software section. The software program, which connects to the board through USB interface, is used for loading the 3D model file for printing and testing various operations. The overall system is powered by 12V, 400W ATX power supply (Fig. 8).
Sanguinololu board (shown in Fig. 9) is a low-cost, all-in-one electronics solution for Reprap and other CNC devices. It features an onboard Sanguino clone using the ATMEGA644P microcontroller, though an ATMEGA1284 can be easily substituted. The board is developer-friendly with expansion pins supporting I2C, SPI, UART and ADC functions. Sanguinololu has a very flexible input power supply that ranges from 7V to 30V.
The stepper motors are powered by Pololu boards that are mounted over Sanguinololu board. These are carrier boards or breakout boards for Allegro’s A4988 DMOS microstepping driver with translator and over-current protection. The stepper motor driver lets you control a bipolar stepper motor at up to 2A output current per coil. Fig. 10 shows a Pololu board with heatsink.
The heat-bed (Fig. 11) normally heats up to 110°C when powered through the dedicated connection on Sanguinolou board. The power supply should be able to deliver at least 300W and wires from the power supply to the Sanguinololu board should be capable of handling 20A or slightly more current.