Small CNC router

Hi all, just joined this group...

I purchased the Hobby CNC kit from Dave Rigotti, but I'm not satisfied
with the size limitations of the table plans. I'd like to be able to
cut up to 12"x48" wood sheets.

My problem is I know nothing about the various extruded aluminum
pieces, etc. that a lot of folks seem to make their units out of. How
do I know what parts fit in what, what bearings and leadscrews will
fit, etc.

I need an education on these parts. It seems to me I could design my
own table easily enough, if I just knew what preformed parts are out
there.

Or I can also make my own parts, being a machinist.

Any leads, websites, reading, catalogs that have very good
descriptions of their products, etc?

John