Complete Beginner requiring advice!

[D.C.]

Welcome to the forum, it is always worth having a good read of the build logs to see what people are using and problems that crop up.

Router Build Logs

I'm not one of the resident experts but I have read a fair amount of the advice so I'll try to condense some of what you will probably find by doing lots reading.

For the dimensions and materials you have specified, 1610 ballscrews would probably be fine, you can order them from linearmotionbearings2008 on ebay.
If you can afford proper linear rail, buy it. If you can't afford it or don't need super accurate cutting, use supported round rail. You can order this from the same guy on ebay that sells the ballscrews. Do not even think about using unsupported rails or an angry Yorkshireman will beat you with them.

The popular 3.1Nm steppers from cnc4you will probably work for you.
Nema23 3.1Nm

Try to avoid the TB6560 stepper drivers, they generally suck.

The water cooled 2.2kw spindles from China (ebay again) are very popular here and should do what you want just fine.

If you can weld or swop hobnobs for welding services, make your frame and gantry out of steel box section, it's a lot cheaper and stiffer than aluminium extrusion. Make your frame and gantry very, very strong and include lots and lots of diagonal bracing.

If you have a good idea of what you are going to be using the machine for, don't put an excessively long z-axis on it. As you are building your own machine, don't be afraid of considering things like a future 4th axis or a gantry that can overshoot the end of the table for cutting dovetails or strange sized stock if these things would be useful to you.

If you only have a little workshop consider making a vertical machine to save yourself a lot space.

Use a dedicated PC if possible for your CNC machine. If you don't mind linux, linuxcnc is great and free, if you really want windows then don't forget to budget for a copy of mach3.

Once you have budgeted for all the big stuff like screws, rails, steppers, drivers, power supply, frame materials, spindle add about 30% to cover all the little bits like cables, tubing, water pump, bolts, paint etc.

Hope that helps you get started. :)