Nuts and Volts - April 2014

Laser Power Supply

eBay had an amazing deal on high-power IR lasers. I want to build a laser cutting tool with one of the laser diodes. The heatsink isn't a problem, but I'm having trouble designing a constant current power supply that can handle the 50W laser. The commercial power supplies are hundreds of dollars. Any suggestions?

#4146 Carl Edwards

Santa Fe, NM

[#2142 - February 2014]

Laser Cutter To 3D Printer

I want to move from a mill to a 3D printer to fabricate parts. As far as printing materials go, I've heard that regular plastic is toxic and print quality is poor, and the PLA alternative is brittle and heavy. What's the best printing material out there? Are there better choices?

3D printers (a.k.a., rapid prototyping machines) and laser cutters are very different animals. The laser cutter can be used to "machine" metals by laser ablation of the surfaces. A 3D printer (such as MakerBot) uses a curable plastic powder or filament for producing layer upon layer renditions of whatever you draw on a Computer Aided Drawing (CAD) system.

Polyethylene Terephthalate (PET) filaments produce stronger products than the usual ABS plastic materials. (A UT Austin student reportedly made a working pistol out of ABS but I am not sure I would want to trust my safety to the strength of plastic in this case.)

The replicator (3D printer) will run about $3,000. MakerBot also sells a digitizer for about $1,000 which allows you to reproduce an existing product by scanning it into the computer versus the laborious process of producing a 3D CAD drawing. Using the replicator and the digitizer/CAD

system together makes it possible to produce nearly anything you can imagine as long as it fits into the 3D printer. I have seen a complete ball bearing set made as one piece (no assembly required) on a old 3D printer which moved exactly like a metal bearing produced by sophisticated machining processes, but the plastic did not have the strength to hold up in service. I can see using ceramic materials which can be fired to produce strength as a future wave in 3D printing. Tim Brown PhD EE, PE via email >>>YOUR ELECTRONICS QUESTIONS ANSWERED HERE BY N&V READERS