You want to build your own DLP 3d printer? You have come to the right place! Welcome to the start of a series of posts describing the steps towards building your own DLP 3d printer. We’ll start with the part that’s probably most intimidating to many people: the electronics.
What do you get here?
This post will provide information on the electronics set-up that I use in my future DLP 3d printer. It will concentrate on the schematics and components needed for your own DLP print controller board. The main aspect of the design is simplicity. I will only use widely available, relatively cheap parts like an Arduino Pro Micro and Pololu stepper drivers that are well established in FDM printers.
What needs to be done?
OK, what do we need for the print process to work? In essence, there are four devices that have to work together:
- A projector to illuminate the resin with a given exposure time,
- an actuator for closing a mechanical shutter between exposures to block excess light from the projector,
- another actuator that drives the build platform and
- a third actuator for the vat tilting mechanism.
All these devices have to be controlled in a precise fashion during the print process. To do all this, we use a micro controller and a PC connected to it.
General electronics set-up
The following picture shows the general set-up of all the components. It may look a bit complicated, but fret not! I will walk you through the whole thing.
The micro controller, stepper drivers, step down converter and a 60 mm cooling fan will be contained in an electronics box to keep the whole thing clean and tidy.
Detailed circuit description
In the following section I will show the main parts of the DLP 3d printer electronics: the micro controller, the stepper controllers and the end switches.
Micro controller: The main part of the circuit is an Atmel AVR AtMega32U4 8-bit micro controller. The special feature of this controller is the integrated USB interface which makes it very easy to hook it up to a PC for sending commands or updating the firmware. To keep things simple I use an Arduino Pro Micro board that comes with this controller and also has a 16 MHz quartz and all the necessary peripherals and a USB connector. The USB connection also serves as a low current 5 V power supply. You can get the controller board for less than 5 € on eBay.
Stepper motor control: The stepper motors are driven by Pololu DRV8825 drivers. You can get them for about 5 € per piece, for example on amazon.
They are very easy to control via 3 pins of the micro controller: One for the direction, one for the step signal and the last one for activating the stepper. While the direction and enable signals can be connected to any generic pin of the controller, the step signal is connected to one of the micro controller’s timer output pins. This way, we can use the hardware timers to create the step signal.
End switches: We will use optical end switches as they are wear-free and very precise. I have chosen some Everlight ITR8102 photo interrupters, but most types will work. The signals from the photo interrupters are low pass filtered before being fed into the micro controllers hardware interrupt pins (INT0, INT1 and INT6). Maybe the filtering is not necessary, but this will be evaluated during testing.
OK, that much about the circuit details. For the whole picture see the circuit diagram of the complete electronics below.
What do you do with all this information?
Well, build it of course! I have done so using a prototyping board. The result combines the main controller and the stepper drivers on one board. There is still some room for the step down converter which did not arrive yet. The stepper motors, end switches, projector shutter servo and power supply will be connected through a set of headers on one side of the board. There will probably be a nice custom PCB for this once the circuit has been tested.
How much does it cost?
As I said before, I tried to keep the costs low by choosing common and inexpensive components. You should expect the following costs:
- 1 x Arduino Pro Micro controller: 5 €
- 2 x Pololu DRV8825 stepper driver: 10 € for both
- 2 x Stepper motor (get some used ones on eBay): 26 € for bot
- 3 x Photo interrupter: 1,5 € for all three
- Some resistors, capacitors, cables, plugs, prototyping board, misc stuff: 30 €
- 1 x LM2596 step down converter board: 2 €
- 1 x 36 V 200 W power supply: 50 €
Check eBay for good prices, especially for the populated boards (Arduino etc.).
The next step will obviously be the testing of the board and stepper drivers. After that, I will present the firmware for the board (which still needs some cleaning up).
Has this description of my DLP 3d printer electronics been useful for you? Then stay tuned and make sure to comment!
Until next time, Paul