Need help designing ballscrew

I would like some advice from those of you who have seen factory CNC
ballscrew setups for Bridgeport type milling machines...

What i want to know is the lash up of nuts, washers ect between the
bearings and the pulley.

To be more specific, after the 2 angular bearings there is a fine
pitch thread for a nut to tighten up the bearing pair. I am thinking
of making it 20mm x 1.00

A few things i want to know is.

1. How long does the nut have to be to take the force of preload
tension on the bearings.

2. What kind of hardware is usally employed...As in type and
order...Like bearing-groundwasher-lockwasher-nut...Or does the nut
tighten on the bearing...Or is there 2 nuts to tighten against each
other...ect

The bearing house has 2 stock nuts at the 20mm x 1.00 size
one is about .252 inches long for $3.38
another is .512 inches long for $16.85


Wally