Adding Laser Engraver to CNC Router and Activating in Mach3

I wanted to add a laser module to my CNC router so that I could label parts as they were machined. The advantage to doing this on one machine is obviously reduced setup time.

The laser module I used was an ElksMaker 2300mW 445nm blue laser. I got this off ebay for ~$100NZD (70US) https://www.ebay.com/itm/445nm-2-3W-2300mW-Blue-Laser-Module-With-TTL-PWM-For-DIY-Laser-Cutter-Engraver/322382603217?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

You could use a more powerful module, up to 15W for around $300 depending on what your intentions are.

Varitech has a good video on adding a laser module to a CNC router: https://www.youtube.com/watch?v=mZLO07CZD4s

Which helped me to get started. I made some important functional differences in the c

Varitech set the module up to activate for CCW rotation of the spindle and substituted M4 (M4 = start spindle CCW) codes and M5 (M5=Stop Spindle) codes for each up or down movement of the Z axis to activate or deactivate the laser. For my solution, I created new M codes to turn the laser on and off so that the configuration did not interfere with any spindle.

The laser module I am using can be controlled by a PWM signal, I won’t be using this as the module is already low power. For the time being, the intensity of the engraving will be regulated by adjusting the feed rate of the machine.

Safety

Use safety goggles when using lasers. Also ventilate the area properly. Please make sure that the bandwidth on the safety goggles covers the working band of your laser module.

If this experiment works out, I plan to add shielding around the head of the the laser https://jtechphotonics.com/?product=445nm-laser-shielding

And perhaps, active carbon filtration using the dust extractor blower.

Wiring

To power the laser, I am using the onboard relay on the CNC controller board. Typically this is used to drive a spindle, but It is not being used in my case so it was free to provide power to the laser. As the relay switching is not instantaneous, the laser lags somewhat from the intended start time. In future, the power to the laser could be switched on by the relay and the laser ‘fired’ from another of the output pins.

The break out board I have is a: PMDX-122 the laser is wired in series with the relay and 12V source.

Configuration

In mach3, the output needs to be mapped to the correct pin. On this board the relay is activated by Pin 1.  

Code

Mach3 has VBA support. This allows the user to write scripts and save them as macros. Macros can be called from GCODE by saving the macro as an “M##” file in the Mach3\macros\Mach3Mill directory.

Access the VB script editor through the menu shown below

Scripting is extremely powerful and useful. I found this video really helpful getting started: https://www.youtube.com/watch?v=J9r3aTRCEo

‘This script enables a laser to be switched on by calling M301 in the GCODE file.
‘’Output1’ must be mapped to ‘pin 1’ which has the relay for direct driving a spindle.
ActivateSignal(Output1) 

‘This script enables a laser to be switched OFF by calling M302 in the GCODE file.
‘’Output1’ must be mapped to ‘pin 1’ which has the relay for direct driving a spindle.
DeactivateSignal(Output1)

Below is a simples GCODE program to test the laser

G54 F1000 (run in local co-ordinates at feedrate of 1000mm/min)
X0 Y0 (move to X0,Y0)
M301 (run script m301.m1s - Turn laser ON)
X50 Y0
X50 Y50
X0 Y50
X0 Y0
M302 (run script m302.m1s - Turn laser OFF)
M30 (Rewind)

Test

Results

Below are the results of the above video close up.

The smoke really effects the quality of the engraving by interfering with the beam. For the the second test I switched on the dust extractor faced the inlet toward the laser.

The artifacts from the delay in the relay switch time are quite noticable here. This is something to be improved on possibly by adding PWM or a solid state relay.

All in all, results were very good.

Video Walkthrough