Sunday, November 8, 2015

Frickin' Laser Beams

3D printers are awesome!  I love using mine to repair widgets and toys, and make whatever random objects come to mind.  However, I've sometimes come to find the technology limiting.  First, it's not really great at making finished goods.  Also, the build materials are primarily constrained to a few types of plastic.   Finally -- and perhaps most importantly -- it could really use the added sexy appeal of a destructive frickin' laser beam.

Frickin' Laser Beam
Makerspaces are often equipped with laser cutters (aka laser engravers), providing an excellent compliment to 3D printers. Capable of cutting or engraving shapes and images into wood and plastic, and even etch images into glass, the results look completely professional, as they use the same process (if not the same machines) as commercial manufacturers.

For a hobbyist, I've always assumed that astronomical prices would keep the purchase of a laser cutter permanently unaffordable, or at least spousally indefensible.  In the last few years, however, a number of low cost Chinese laser cutters have come onto the market.  Instead of $3500-$15,000 or more, these bargain units have literally decimated the entry-level cost barriers to the technology.  And while the software can be awful and the hardware relatively crude when compared to their larger brethren, these laser cutters can be surprisingly functional and excellent platforms for hacking, modding, and upgrading.

Unboxing my K40
The king of these low cost laser cutters is the K40, a generic name for a family of similar devices assembled from different Chinese manufacturers using the same or similar parts.

I discovered them while investigating sub-$200 mini engravers -- compact devices built around the laser diodes used in DVD burner drives -- units capable only of slowly burning patterns into small wood objects such as keychains and cell phone cases.  In doing my research, I was surprised to find out that for only a little more money, I could purchase a full size unit built around a real laser.  Instead of a laser diode, a K40 uses a water-cooled 40-watt CO2 laser tube, and is capable of not only engraving, but cutting through 1/8" thick acrylic, cardboard or plywood.

Direct from China, one can get a bare-bones K40 on Alibaba for as little as $300, but I chose to pay only slightly more on eBay to get one from a US-based distributor.   It arrived a few weeks later, packed in an abundance of foam and cardboard.  It was larger than I expected, but I found it a temporary resting place on some ottomans in the Monkey Man Cave.  I'd work later to build it a unique permanent home, which I'll detail in a future post.

The laser cutter came with a submersible aquarium pump to circulate the cooling water and a moderately janky exhaust hose and squirrel fan to remove the gases and smoke generated when engraving.  In a few minutes I was able to get up and running, placing the pump in a vat of distilled water and routing the exhaust hose out the door.  All I needed to do was fix a poorly-designed ground connection (paint doesn't conduct electricity folks!) and adjust the mirrors to get a properly aimed and focused beam.

I was half expecting to see a satisfying lightsaber-like beam, but sadly, a CO2 laser only produces invisible infrared light. It does have the capability of blinding its operator without advance warning, however, so I was sure to order a pair of CO2 rated laser glasses to wear when working with the cover open.

The weakest component in the system is the software.  The laser cutter only works with MoshiDraw, a program that runs under Windows and functions both as a driver and structured drawing program.  It's buggy and confusingly organized, and the English translation is absolutely atrocious.  However, the program is quite functional once you figure it out, and is capable of completing a wide range of projects.


As a warm-up exercise, I first tried making some test cuts in paper, essentially using the engraver as an oversized, overpowered Cricut, those computerized die cutting machines used by scrapbookers to make paper hearts and doilies and such...  except of course with the added satisfying (and may I add manly) power of a death ray laser beam.

To follow up, I tried my luck with plastic.  Using two-tone copper/black laminated acrylic sheet, I cut and engraved a replacement for the laser cutter's own control panel, which I had enhanced with a few extra switches and knobs.

Cutting acrylic laminate
Completed panel
Installed panel

I used a similar material to make bookmarks engraved with a MakerMonkey logo I drew in Photoshop.

Lastly, I tried the laser cutter on plywood, scorching the same logo into the surface, making this custom engraved coaster.
Laser Cutting Plywood

The possibilities are endless for future things to make, but the laser cutter couldn't stay in the middle of the room forever.

First, it needed a permanent home, and of course something ordinary just wouldn't do.

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