My K40 Laser Cutter

In the beginning of 2017 I came up with the idea of getting my own laser cutter. I do not remember exactly how I got the idea, but I soon saw all those possibilites with such a machine. The ability to cut and engrave materials like wood, acrylic or leather sounded great for a tinkerer like me. I did lots of research about this topic, since a laser this powerful can already be really dangerous, especially for your eyes.

Just a couple months later I got my K40 laser cutter. This laser has a power of a bit less than 40W (a regular laser pointer for comparison usually only has 1mW which is just 0,001W). There are different kinds of lasers, this one is a CO2 laser. A CO2 laser usually uses a long water cooled glas tube, filled with gas. The laser beam created by this tube is infrared, meaning you can not see the laser beam, which makes it even more dangerous. The tube on this machine is hidden beneath the white cover on the back. To be able to control the beam, there are 3 mirrors installed.

There are different version available of this laser, one version with a potentiometer and an amperemeter to adjust the power and another version with a digital control but no amperemeter. I bought the analogue version with the potentiometer, but I soon upgraded to a digital control board, while mainting the amperemeter, which allows accurate and easy setting of the power. Recently another upgraded version of this machine was released, which already has some of the following modifications.

To see what is going on inside the machine I added two led strips to light up the inside of the machine.

It is important that the water temperature does not get too hot, otherwise the laser loses power and the tube can get damaged. To ensure the water temperature does not get too hot, I installed a temperature sensor, which displays the current water temperature.

After a few weeks of using this machine I already was annoyed of the clamp iside, which is meant to hold the object which will be cut or engraved. For this reason I did some research and found a video where someone made a spring loaded bed, so the top of the work piece always is in focus of the laser beam. I really liked this idea so I took this idea and created my own version of a spring loaded bed.

Another modification is an adjustable laser head, so you can set the focus point, wich is really important.

To get clean and deep cuts an air assist is necessary. Therefore I use an airbrush compressor in combination with a 3d printed nozzle to blow air near the focus point. Additionally I installed an air pump to the laser head, which helps blowing away all the smoke and even keeps the lense clean, by blowing out the smoke. For routing the hoses for the air assist I installed a cable chain to the back of the machine, I had to do some modifications to it, to make it fit.

Another problem with such a machine is dealing with the fumes. The smell of wood is not that bad, but for example cutting acrylic smells really bad. To deal with the fumes I installed a much more powerful extraction fan. From now on alomost all the fumes vent outside and only very little smell enters the room.

To be able to cut when it is warm outside and the water temperature is too hot, I installed a few peltier coolers to decrease the water temperature. But to be honest this modification was not as effective as I was hoping. Better save some money and invest it in a proper water chiller.

So far those are all the major modifications I did to this machine. Even though the machine itself seems really inexpensive for what it is, but with all the modifications it also got much more expensive than I expected.

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