Re: robotic workcell design

Hi Dave,

Thanks for the very detailed response. You gave me a new perspective
on some parts of the idea.

The requirement for only new parts was desired so that people could
be guaranteed to be able to build the universal gantry...I like that
term :-...in a timely manner with predictable specifications. I know
using ebay parts would allow a cheaper design, but then compatibility
is out the window. At that point, you might as well start the
construction article by saying "First, obtain a gantry cnc machine."

Perhaps the requirement of limited machining and hand tools needed is
too strict. Personally, I have a fairly large shizuoka cnc bedmill,
so I could make a lot of what this gantry would need. I *know* I
could make it for less than $2000 if I use my cnc mill, but I am
thinking that there are quite a few people who would be interested in
a project like this that do not have those type of tools.

The CO2 laser thing I mentioned because I happen to have several and
have built some slow speed engravers already. They are not *that*
dangerous..I can still see pretty clearly out of one eye :-)
Seriously, CO2 is probably the safest wavelength laser out there.
10,600nm is almost 100% absorbed by plastic, glass, etc., making eye
protection as simple as a pair of $3.00 shop goggles. A plywood
cover with an acrylic window could be made to cover the whole gantry
for the super paranoid types. If the beam coming from the laser is
shielded up the to focal point (which you would do since you want to
have positive air pressure fed into the nozzle to keep smoke and
debris off of the ZnSe focusing optic) then laser light reflected
from shiny surfaces will diverge to non-dangerous levels in a pretty
short distance. This assumes you would be using a short focal
length lens, which of course you probably would since you want a high
power density and small spot for engraving annodized or painted
metals, wood, etc. I use a 1.75" FL ZnSe lens with a 10 watt Synrad
CO2 laser (actually doing about 17 watts) for most of the stuff I do.