Thoughts on the K40 Laser Cutter/Engraver

Laser Cutting

I love my laser cutter/engraver. However, I don’t think it is for everyone, serious care needs to be taken to mitigate some serious issues. Here are some rambling thoughts.

  • View this thing as kit. Do not think of it as a plug and play or turn key.
  • The grounding on this thing is crazy. The high voltage supplies on these things are often grounded to chassis. So, if anything ever goes wrong with your house ground, or an internal ground, you’d find out about it when you touch it and wake up dead. Also, the resistance between your house ground rod and the device is probably enough cause problems. Plan on modifying grounds to make this thing safe. If this doesn’t make immediate sense to you, don’t buy this thing.
  • In keeping in mind with the above, drive a ground rod dedicated for this thing. Ground the laser cutter’s chassis to it with heavy gauge wire. Use the ground rod! Make sure it stays connected.
  • This thing can blind you instantaneously from only reflections. You can’t see the laser light, so it can lull you in a false sense of security.
  • It does not even come with a micro-switch to cut off laser power if you open up the lid. Don’t say, “I’m not stupid enough to open the thing when in use, so I’m good.” One, yes you are that stupid, you are human. Two, you might not the only one that comes in contact with the machine. It would be hard to live with blinding some youngern (perhaps your own). INSTALL A MICRO SWITCH. I just put a micro-switch inline with the laser enable wire, that kills power to the laser if the door opens.
  • I WILL NOT BE IN THE ROOM WITH THE THING WITHOUT WEARING WAVELENGTH RATED LASER GOGGLES. If anyone else is in the room, make them wear googles too. This thing was made in China, as cheaply as possible. Think about it.
  • You are an idiot if you you don’t have a fire extinguisher handy.
  • Installing an e-stop is a good idea.
  • Air assist is not an option or a luxury. Consider it safety gear. It keeps fires to a minimum, and greatly increases the quality of the cut/engraving. You can buy aftermarket nozzles, or focusing heads for dirt cheap.
  • Get a water separator for your air assist. I didn’t do this, and ruined a lens. Lens are not expensive, but you don’t want to loose the cutter right when you want to use it. Probably not a bad idea to have a spare lens lying around the shop.
  • Do not max out the current. I rarely go over 10 mA. Laser tubes are expensive.
  • A flow switch for your coolant circuit is a good idea. Tie it in to an e-stop, that way if you stop flowing water with the stupid little aquarium pump, it will cut off the machine before toasting a couple hundred dollar laser tube.
  • Propylene Glycol is your friend in your coolant. Even the food grade stuff is pretty cheap. You don’t want water to freeze in your laser tube. Remember, it is just glass. Winter, I keep water flowing to prevent freezing. Spend some time considering how to prevent water from freezing in your laser tube.
  • Don’t use tap water. Buy the distilled water. It don’t cost much. Not worth risking your water being conductive, and having the high voltage arc around. Can’t image anything good coming from that.
  • The platform that comes with the device is crap. Plan on making your own.
  • Learned this weekend the joys of custom jigs to hold your work piece. Take the time to make one, if you plan on making more than one of something.
  • I typically use 1/8″ door skins for my wood cutting and engraving. The laser will blow right thru it on one pass. I set my speed around 8 mm/s. Again, air assist is your friend.
  • If you are looking for things to cut, Dollar Tree is your friend.
  • Spend time with your exhaust system. The one that comes with the device is worthless. Just replace it. You do not want to be breathing most of the things you are cutting. Many ply-woods have glue that is formaldehyde based. It’s what cancer smells like.
  • I’ll sometimes use dry-molly to mark metal. It is MUCH cheaper than CerMark. However, no telling what this will do if you eat it. I can’t image it will do anything good to you. Clean it and then clean it again. Rubbing alcohol seems to take off the excess pretty good.
  • Don’t cut in your house. You want to do this in a detached building from the one you live in. Perhaps a garage, but this is iffy.
  • A respirator is a good thing to have around. When in doubt, wear it.
  • I moved and replaced the micro-switches used to zero the table. You can get a few extra inches out of the device if you put some time into this. Especially, if you modify the exhaust duct that goes way to far into the cutting area.
  • Put a web-camera inside the cutting area. It makes watching the cutting process much more pleasant and safe.
  • One of the first things I cut was a “laser in use, do not enter” sign. Not a bad idea to have one, and hang it on the door when using the machine.
  • The software that comes with it sometimes has a mind of its own. On occasion, mine will finish an engraving.. and for some reason move over and down about an inch and start engraving over again. This software will do stupid stuff. You’ll get used to it, but you will ruin work pieces. Don’t put anything irreplaceable in it.
  • Make some sort of a log for the settings you use on various materials.
  • If you are not comfortable doing modifications like this, this thing isn’t for you.
  • K40 Whisperer is your friend. I wasted far too much time using the buggy software that came with it. Ditch it. Ditch it as fast as you can. K40 Whisperer makes the experience MUCH, MUCH more pleasant. I’m even toying with putting it on a Raspberry Pi, and a touch screen. Nice stuff.
  • Despite all the above, it is great fun. I’d buy it again if I had it to do over. I enjoyed modifying the cutter/engraver almost as much as using it. But view it as a kit. Don’t forget how cheap a piece of kit it is. The tube is around a couple hundred bucks, so they didn’t spend much money on the rest of the cutter. … but it is a freaking 40 (30 really) watt laser that mere mortals can afford.

This thing is kinda a death trap, so no warranties expressed or implied on the accuracy, completeness, or safety of my comments above. This is all at your own risk. You are buying a cheap laser from China. Your safety is your responsibility, not mine or anyone else. Don’t rely on some random person on the internet to keep you safe.

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