Newbie- 1st post,newbie question

[eran k]

Hi all,
my name is Eran, this is my first post here.
been lurking for a while and finally decided to build (or try to) a CNC router...of course.
I have few questions and i'll try to be as specific as i can, please excuse me if i get the terminology wrong or ask dumb questions.
it's a bit long so please bare with me
also if there are things i forgot to ask, i'l be happy to hear

my machine size and purpose:

1. I have limited space and wish to keep expenses low so was thinking 3' by 2' moving gantry machine
2. The tool will be some kind of dremel clone
3. i wish to cut balsa, ply, depron, EPS, Plastics and perhaps other types of wood

machine frame and linear slides

1. the machine will be built from MDF, will 19.5mm thickness do?
2. I was offerd "real" linear guide rail for about 50$ a piece, i think it can make things less complicated and more accurate then building the slides myself like i saw here with round piped and skate bearings etc. am i correct? can the MDF frame handle these rails as they are quit heavy.
3. How should i build the frame if i'll use the real railes oppsoed to using pipes and skate beraings slides?

Screws

1. It look like real ballscrews will be out of my budget,so i'll use Threaded rod instead,will it work and be good enough for the purpose?
2. when using threaded rod,what to use for the nut,how to attache the nut to the stage?

Steppers

1. what type of steppers should i use? bipolar or unipolar?
2. what size of steppers should i use for a machine this size?

Electronics

1. do i need a driver for each motor and a controller board to connect to a pc?
2. does a kit like hobbycnc pro board and the similar products include everything i need except power supply?
3. is a 24v power supply a must?, can a pc 12v PS be used?

Thanks
Eran

[rlwoodjr]

I used a dremel for my first cnc, it did not last very long. I f I had to spend a little extra for a router, this is one place I would.

I like the linear rails, but they do add cost. A lot of folks have built with pipes, plates, and bearings

Acme thread is not to expensive and you can make your own tap that will work to make plastic nuts.

Yes, you need a driver for each motor. HobbyCnc board is a quality board with 3 to 4 axis build in. It does like 30 to 40 VDC...I would not recommend a power supply below 30 VDC for this board.

I like TurboCnc for the controlling software...

It all comes down to how much you want to spend and what you are going to do with it.