The device you seem to want sounds like a slightly larger version of the
mechanical stage used on microscopes to position slides at very high
magnification, such as 1000x. While I don't recall the exact parameters, I
do know that it's possible to locate a single bacterium, remove the slide,
do other things with the scope, then replace the slide and re-locate the
same bug within seconds.

To be fair, one usually reads the stage verniers relatively grossly and then
homes in on the subject by using landmarks within the field of view, but a
good mechanical stage is a fairly decent precision instrument. Other
manipulators allow one to insert an extruded glass syringe into the middle
of a single nerve cell - or an ovum. Good enough?

If you need more range than one of these stages can provide, could you
attach it to a moveable base that would allow you to position it grossly,
lock it down, and then use the finer capabilities of the stage itself?

http://www.greatscopes.com/acc.htm is just one location. They sell one for
$39. I've never dealt with them, so this isn't an endorsement of the
company, but Google "mechanical stage" and see for yourself what turns up.

You can go all the way from this low-end device to spending beaucoup de
bucks on a Zeiss. Also, don't overlook the used market. There are loads of
companies selling relatively inexpensive high-end microscope products in
outstanding condition that have been re-cycled, damaged in some way that
won't matter to you, reconditioned, upgraded, etc.

DanD

"Absinthe" wrote in message
s.com...
How accurate of a machine can be made from wood? I am considering building
a
small 3"x6" slide table (x/y positioning device) but ultimately it will
have
to be accurate to .001 so I am thinking I would be better off in some sort
of plastic or metal...