Other lasers can be connected via the x and y axis motor outputs on the shield as long they use stepper motors. You can feed the steppers with maximum of 35 Volt on the power connector on the K40 shield. The controller is fed via the same power connector via the 5V pin. The Power stepper and 5V share a common ground.
The LO Yellow pin on the connector can be used to switch on the laser (e.g. laser diode power module – switches the 24V White input to LO).
Next to the power input connector are the X- and Y-endstop inputs.
The PWM output is the last connection on the right of the small connector next to the another small 4 pin connector. The ribbon connector on the top of the picture above is not used.
An example below is a Trotec laser which comes with analog bush motors with rotor encoder feedback. I customised the motor mounts so I could replace them with standard stepper nema17 motors.
Above is the new replacement bracket for the NEMA17 motor and the old bracket for the brushless motor.
The installed NEMA17 replacement stepper motor driving the X-Axis.
The laser itself is an RF excited laser which is driven by a 1.9kHz PWM – mode 2 (see the customised $28 – link: parameter in Grbl)
|PWM Laser freq||Value||PWM mode||Remarks|
|244 Hz||0||fast pwm||great engraving|
|61 Hz||1||fast pwm||dither effects|
|1.9 kHz||2||fast pwm||just b/w|
|15 kHz||3||fast pwm||just b/w|
|Default||0||fast pwm||Default mode|
|122 Hz||4||phase-freq correct||great engraving|
|1 kHz||5||phase-freq correct||just b/w|
|7.5 kHz||6||phase-freq correct||just b/w|
Also the laser is way narrower than the K40 hence you see small lines. A diode laser needs driver electronics (constant current/voltage) with a TTL input that accepts PWM.
I have ran a small 500mW laser diode with Gerbil.
The laser driver here is a homemade circuit based on LM317 voltage regulator.
Two pictures, one above with the K40 and below one with a diode laser.
The Diode based laser and its big brother the K40 next to each other.
Hope you enjoyed this write up and inspires you to build your own laser!