If you have just bought a new K40 laser cutter or have replaced your mirrors, chances are that you are going to need to align your mirrors
Although this demonstration is using a 50W ebay Chinese laser cutter, the principles are the same if you are using the K40 laser cutter. This process doesn’t need to be difficult.
All in all your K40 laser cutter mirror alignment should take between 15-30 minutes to compltete
You can watch the full demonstration and a detailed written guide here