From the home office at Instructables comes another weekly email blast, this one featuring a small low power laser cutter/engraver. The thing I like about this one is that it’s built from scrounged DVD burner parts. Building an X/Y table is straightforward in concept but complicated by the details of picking a drive motor, gearing belts, bearing surfaces, and assembling everything square. In this case the author ripped apart 3 non working DVD burners, and used intact the stepper motors and sliding mechanism from two of them. The laser is also reused to do the etching/cutting.
Hardware and Software
Mechanically one sliding mechanism is used for the X axis. This one sits flat, and the work piece is placed on top of it. The other mechanism is mounted vertically and moves the laser in the Y axis. The steppers are driven by an EasyDriver board from SparkFun. They are used in microstepping mode to increase the resolution of the cutter (although the actual resolution isn’t specified).
An Arduino rounds the whole thing out, running software that translates G code (the language that CNC type machines use) into linear motion of the two positioners.
The overall flow is to draw the design in Inkscape, which is an open source vector editing program. It, along with an extension, is able to generate G code that reproduces the design. Finally a small program written by the author sends the G code to the Arduino via the serial port. All of these downloads are available in the Instructable.
The most obvious limitation of this design follows directly from the simplicity of the mechanical assembly. Using a pre-assembled DVD positioner means that you’re limited to the displacement of that system, which is about 1.3 inches, giving an area of about 1.7 square inches. Pretty small, but as shown in the Instructable, enough to do some small engraving.
So the first improvement would be to get a bigger table. I can’t think of a larger positioner from a computer, except maybe a head positioner from one of those antique 8″ floppy drives. Or maybe one of the old laser disk players? If you can’t scrounge a larger positioner for free, then the next best thing is an affordable one that can be adapted. A quick search turned up a 12″x7″ table from Grizzly (G8750) for $120. It’s a mechanical table with handles and vernier scales, but I think it’d be fairly simple to remove the handles and fit a pair of stepper motors.
Over on cnczone.com one of the users had the same idea, although the thread is very recent and the idea of fitting steppers in place of the handles is still only an idea.
The other improvement would be a more powerful laser. That would speed up cutting and allow etching of metal surfaces. DVD burner lasers seem to be around 200m, and BluRay lasers seem to go up to 400mW. Surplus laser supply places have laser diodes in a wide variety of powers.
So for less than $200 you could have a larger XY positioner and a 1W or bigger laser, and the only fabrication you would have to do would be to mount a stepper motor in place of a handle.
Design News Gadgeteer