questions before building

Hello List,

I have a couple of general questions that I could not find answers to
in the FAQ. I have searched in the archives a bit, but the amount of
posts is making my particular questions hard to find since they
contain some very common keywords. If anyone can suggest threads
where some or all of the questions are dealt with, I would be very
appreciative. I could read these threads and come back with more
refined questions.

Over the last year I have been collecting surplus hardware to build a
CNC router. I now have 4 Nema 23 steppers with optical encoders, 4
CMD260 micro stepping drives, a parallel port interface board (EMC
compatible), and other bits and bobs of thrust bearings, drive
couplers, etc.

The material intended for milling and routing is Perspex, plastics,
aluminium sheeting, wood, and general soft metals (just hobby
stuff). I am thinking about driving the axis with threaded rod, and
using brass bushings on solid rod as the axis guides (e.g. like many
have already done). The design will be a gantry style, with 90cm x-
axis, 70 cm y-axis, and 10 cm z-axis.

Initially I was going to use a hobby rotary tool for the spindle
motor, but have decided to first look at something more powerful to
base the z-axis design around. I figure it would be easier to alter
a set-up made for a cutout tool to accept a small hobby rotary tool
than visa versa. I also thought that if I am making this thing, I
might as well not limit myself from the start. I can always go
backward to the rotary tool I already own.

My questions are these.

Motor suggestion/recommendations, things I should consider:

I am interested in finding a motor that is... in order of importance:
able to cut the above materials, quiet-ish, light; accept variety of
tools (cutting, routing, drills). I am not expecting to find the
optimum for all these categories in one tool, but some balance. With
thread-rod, I don't expect the feed rate to be blistering, but I
would like to not worry about going slower to accommodate the motor,
and I may upgrade the drive system at some point.

Adaptability of the motor in holding tools:

I am also wondering about the tool holding ability of these motors
(cut out / router). Can one use a variety of tool shaft sizes, or
are they limited to a standard diameter, and thus maybe rule out
small drill bits and accessories (pcb drilling, etching)? I am
planning to have the ability to attach my rotary tool for smaller
jobs, so it crucial. But I might pick one motor over another if it
has more versatility in what it could hold.

X-axis coupling

I am planning to have two x-axis drives. Is coupling these
electronically (splitting the x-axis step and direction to two motor
drivers) a good route to go? Should I mechanically link the axis
drives with a belt? And if so, should I leave the second stepper
inline? I do have optical encoders on the steppers, and though it
might be possible to have each x-axis stepper act independently, but
always carry out the same command. I could then use the feedback of
the encoders to make sure that x-axis and the "4th-axis" steps were
successful. I am definitely attracted to the just coupling
electronically, and counting on relatively few miss steps... not sure
if this is reasonable.

Thank for any help or advice you can give

Andy