need info please. on bits and liner rails. if you all don't mind

ok i been running my cnc since 2007 off and on.
i move a lot so i not had no time to learn like i wonted to.

i have some things i do not understand that good cause i had no time to learn them. and i would really like to learn this. not just keep asking for a size and what to use.
what i am saying is. i wont to know everything there is about cnc.. make's working with cnc much easier.


my first thing is bits.. is there a link or somewhere i can learn about ball nose bits and tapered bits. v curve.
i have only used up-cut and down-cut bits. how to read the size of bits.
i wont to understand what bits do what. if i do not have a bit what i can use or do.


sic thing i really need help with is liner rails and acme screws.

i built 3 cnc's sic 2007. one came out perfect.. i had someone get me the liner rail and acme screws i needed. i built the rest my self
so i did not get to learn liner rails and acme screws...

i wont to build a new cnc. my table is is very small. i can only cut a 8x10 frame.

and to do this. i need to learn how to size the liner rail and acme screws for my table... seems simple right.... well hmmm no.. is the 20mm to thin for a long rod? the price is crazy!! acme screws. can i go to home depo and just by a long ass bolt. instead of putting 200$ out on a acme screw. way is the size not the same from a acme screw and liner rail....

i wont to know all i can on cnc.. so if you got info and willing to share please do..


also i am working on grammar so i am sorry. English is not my best with spelling. but i do try