K40 Laser Safety and Comfort Addon

Long time ago during the Google+ time I shared some info about my PCB that adds some safety and comfort features to the K40. 2 years later I found the time to document it.

It adds:

  • Interlock functions for the doors
  • Interlock for water temperature and flow
  • Automatic start and afterrun for 4 relay outputs (AC 115V/230V) and two 12V DC outputs

If you are interested, everything is freely available on Hackaday.io.


I was using only a single sided PCB and through hole compenents. So it is easy to etch a PCB.




I’m starting to design something similar myself. It will be low voltage only with external solid state relays to control exhaust and air assist.

Looking at your link, you have the coolant pump in the same cabinet as the high voltage power supply? Seems dangerous to me. I’m all for keeping water and electricity of any voltage, well separated.