Martin Raynsford and the JustAddSharks crew has created a rather unique Arduino-based ‘Etch A Sketch’ laser cutter.
“What happens when you combine a love of laser cutters with a love of cool 70’s toys and an Arduino? An ‘Etch A Sketch’ controlled laser cutter of course,” Raynsford wrote in a recent blog post.
“I always wondered… what if I could control my laser cutter just like drawing lines on an ‘Etch A Sketch’?”
The JustAddSharks crew kicked off their impressive project by using a Blacknose Laser Cutter, bypassing the control board to drive the laser tube and stepper motors. An [Atmel-based] Arduino Pro Mini (ATmega168) controller was then patched into the machine’s wiring using the existing connectors to interface with the Leetro controller.
“The schematic shows the connections we made into the control system. The onward items like the stepper motors or laser tubes have not been drawn because they were not modified and use all the existing wiring,” Raynsford explained.
“The [Atmel-based] Arduino Pro Mini (ATmega168) works as the controller. The analogue input pins are configured for use as general IO to provide the additional number of inputs required from the rotary encoders. The pulses for the stepper motor drivers are provided by the Timer 1 PWM hardware module. The laser module power is controlled by Timer 3.”
The software, says Raynsford, is relatively simple. When the machine is activated, the laser attempts to drive to the zero position. Meanwhile, both X and Y axis are driven until they hit the end stops. Once both axis are pressed against the limits, the controller moves the axis forward again until they no longer press the switches. The controller then moves the laser head to a ‘Home’ position – a fixed distance from the zero spot.
“When the laser has reached the Home position it is ready to run. The stepper motor drivers require far more pulses than the rotary encoders provide,” Raynsford noted.
“If it was left with a one to one relationship you would need to turn the dial a dozen times to get noticeable movement on the axis. The software detects rotation on the dials and creates stepper motor pulses for a set period of time, this scales up the number of output steps for each input.”
The final version of the handheld Etch A Sketch controller is custom built from laser ply and stained red with Mahogany wood dye, while the screen is actually layer of baking paper to give the device a frosted plastic look.
Interested in learning more about the Arduino-based ‘Etch A Sketch’ laser cutter? You can check out the project’s official page here.
Atmel | Bits & Pieces 