THE K40 Laser
Background
The K40 Laser machine is a chinese non branded co2 Laser cutter and engraver. Even it is called k40 the actual laser output is more like 15 to 30 watts. However it is enough to cut plywood and acylics. How thick of plywood you may ask, well that depends. If we are talking about a single pass i would say 4mm in thickness but as the machine can redo the same pattern over and over again until the cut went through. But there is a catch, each pass will add charring to the wood, the lines will be blurred and the cut will become "unsharp". And no, metals cannot be cut or engraved with the K40 (not even aluminium foil).
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Functions
The K40 also engraves materials like wood, acylics, leather, plastics and tons of other materials.
You can combine both methods depenting on the used software. My machine came with a ripped version of Coral Draw 12 and a plugin called Corel Laser. The plugin adds some icons to the software in order to control the laser and has essentially two modes, engraving or cutting. If i need both, i do the engraving first delete the engraving afterwards and cut the outline of my design. Other softwares do this automaticly depentending of the layout color. Black lines will be cutted, red lines engraved.
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The Machine
The machine uses a co2 laser tube. Other than a diode laser the tube is about 70cm long and sits in the back of the machine. An array of 3 mirrors deflects the beam to the sled (the moving part of the machine). A focussing lens then focusses the beam to the material where the focussed beam evaporates the material. Optional and recommanded is an airassist. A hose connectedto an airpump is connected to the laserhead blowing air onto the working area helping to clear out material and helps avoiding any smoke or particles entering the head destroying the lens.
A co2 laser needs to be water cooled, the K40 comes with everything you need, a paterpump and some hose. For the beginning a buckt of water will do. However distilled water is recommanded. I suggest about 20 L or 5 gallons of water.
Watch out to release any air in the system. Airbubbles can create hotspots in the laser tube, shortening the lifespan of it.
I use a radiator from a PC to keep the water cool as far as possible so as a simple flowindicator for Pc watercooling systems.
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An extraction fan and a hose is also included into the set. Of course lasercutting wood or any other material releases fumes and toxic smoke you will need to evacuate the smoke to the outdoors.
Dangers
Lasercutting is a very dangerous operation.
The actual laserbeam is unvisible as it lies in the upper wavelenth spectrum of infrared, your blinkreflex gets triggered by visible light and even it would, 20000mw of laser light will blind you in a fraction of a second. But not only the actual laserbeam is dangerous but also the high voltage that is needed to generate the beam. 10000 volts dc is needed to excite the glass laser tube. Enough to stop your heart in seconds. A failure in the machine can cause arcing, if the machine is not properly grounded the electricity will go the shortest way what could be your body. In addition it is to meantion that the electricity could also pass through the waterlines into the reservoir.
Lastly lastercutting always causes a fire hazard. I had multiple small fires or embers in my machine, always have a small watersprayer by hand or even a co2 fire extinguisher. Always! cut the power first. A simple rule of thumb is that a Lasercutter that costs around 400 usd cannot be trusted as a piece of rated laserlight shielding macrolon costs about half the price of the entire machine.
I made a video dedicated to the dangers of the K40 that is linked down below.
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