NEWBIE WITH PLASMA/ROUTER ??'s

Howdy from the state of Texas where things are supposed to be
bigger. That saying unfourtunately does not apply to my budget.

A little back ground for those who care.
I am a degreed form a large state university in Agricultural Systems
Management (read: plant and production management for rednecks) with
a minor in electrical engineering technologies. MY current job is
with the R&D dept. of a company that produces high voltage circuit
breakers. I do mechanicla design of large and small mechinisms.

I currently want to build a CNC router/ plasma table. This will be my
first CNC project. It stems from several intrest and needs rolling
into one. I am leting my knowledge of Micro processor design and
Electronic theory slip. I have , after many request, started building
cuatom bumpers for vehicles. This leaves much diamond plate to be
cut. I like the idea of learning new things and honing the ones I
have.

So on to the list of questions.
1. I have decided to do rack and pinion. I think this is the easy
to fit in my non budget ( I am getting married at thanksgiving)
I want to about 14.5 vs 20 PA. It seems from what I know that the
14.5 would seem to be quieter, smoother, more apt to want to push
horizontially on the rack as opposed to up? Is this the case.
What DP of gears do you all prefer Size of racks?

2. I would think that you could make a gantry style table with the
gantry stiff enough to only need to drive one side. Obvisouly a
router has a resitve load. Do I need to drive both sides?

3. How smooth and level does the table for the object being cut need
to be? How smooth and level does the surfaces for the gantry to ride
on need to be?

4. How bout acuracy? Is +/- .03 feasible with a rack and pinion set
up? Can you cheaply get it better? I know every thing perfect a
spur gear with a 16 DP should give you something like .003 backlash?
This would be more than good enough for any thing I do. I also know
its not a perfect would and the demon of stacking tollerances learks
near.

The good news is my company has an employee purchase program so I can
order form our vendors at close to our bulk prices. I have a good
friend that is an excelent machinist and has offered much help just
cause it sounds like an interesting project. I have 3d software and
can use it to drawn my plans. Im young and am willing to let thei
take a life time.


I have another idea in mind when this is done. Bout a 3 axis plasma
cutter to cut fishmouth in tubing and pipe.


Pour on the help :) I am will be more than willing to share my
ignorance...


Jay Y.