added laser cutter to my mill (pics)

CAD_CAM_EDM_DRO
^
LASER :-)

I just added an attachment to my cnc mill. It is a 10 watt Synrad
CO2 laser (doing about 17 watts, go figure). I got it for free from
a semiconductor marking machine that was tossed in the dump. The
lens is a 1 inch dia. 3 inch F.L. ZnSe curtesy of ebay ($25). I am
not really positive it was required to mount the lens as far from the
co2 laser as I did (about 20 inches) but I read that the beam from a
Synrad laser is square in profile at exit and becomes round and
gaussian at about .6 meters from the laser output. Anyway, it seems
to work O.K. In the pics I cut 1/8" basswood at 60IPM, black felt at
120IPM, 1/8" acrylic at 40IPM, 1/8" spongy foam at 100IPM, and 1/4"
acrylic in 2 passes at 30IPM. I am using dry shop air at about 20
PSI into the lens/nozzle assembly I machined on the same mill. I
used a ring of Indium wire to form a seal/cushion for the lens
(overkill?). I tried using nitrogen, but didn't see much difference
than air (and I saw my nice bottle of 2500 PSI 99.999% N2 dropping
all too rapidly :-)

Right now I am just hitting a footswitch when I want the laser to
come on (couldn't wait and just had to see it cut something). My
mill runs EMC and I am going to get a second parallel port and use
I/O from it to turn the laser on/off. What would be a good thing to
use? Does coolant on/off have latency?

Also, I know about the toxic fumes from some plastics and am staying
away from them until/unless I get a fume extractor. I am mostly
cutting thin wood and paper. I designed this so I can take it on/off
the mill in about 5 min. (it bolts to the head of the bedmill). I
always wear plastic safety goggles which are perfect for blocking
100% of the 10,600nm wavelength of CO2. Also, as you can see in the
photo, I have encased the beam inside a metal tube all the way to the
lens, which is a short focal length. If the focused beam somehow
gets reflected, it will be diverging rapidly and would not have
enough energy density to set anything on fire. I might put a
plexiglass shield around the lens head.

Anyway, here are the pics of my $25 CO2 laser engraver/cutter:

http://www.skyko.com/shizlaser/shizlas1.JPG

http://www.skyko.com/shizlaser/shizlas2.JPG