The K40 laser cutter is an often discussed piece of kit that has been around for awhile. It’s of interest as it still represents one of the lowest cost entry points into laser cutters that have enough power to cut thin plywoods and plastics rather than just engrave surfaces. However it’s widely known that the K40 type lasers have a lot of shortcomings and need a fair bit of setting up and modification to make them work well.
This add-on PCB for the K40 laser delivers a few essential features quickly and easily. Many K40 lasers, as stock, have no interlocking switches. This means that if you open the lid during laser operations the laser doesn’t stop working. This is obviously dangerous for the operator. This PCB, with the addition of some switches, makes the machine inoperable until all three doors on the machine are closed.
K40 laser cutters cool the laser tube by running a coolant (water) through a sleeve which is cycled back into a tank with a pump. On longer cutting jobs this coolant can obviously rise in temperature and when the temperature is too high it may damage the laser. This board adds a thermally controlled relay which will cut the power to the laser if the temperature is exceeded, protecting the most expensive part of your machine.
A final feature of this board is it automates the switching on and off of the extraction system. This is a welcome addition as the usual workflow is to only realise you haven’t turned on the extraction when your work area fills with fumes!