Ball screw adjustment?

Hello Group,

Has anybody on this list tried to "make" a preloaded ball nut from
two standard nuts spaced apart? Is this a practical idea for use on
McMaster ballscrews with a lead error tolerance of 0.004"/ft.? I
talked to Rockford Ball Screws and found the price of the 3/4"
preloaded nut was ~6X the price for 2 McMaster regular ball nuts.
When "lead error" is quoted, is the error a linear additive, or
variable amount? Restated, is the 0.004"/ft error consistent on the
next 12", or is it some other distance on the next 12"?
I'm getting ready to order the 3 screws for the GEM 500 machine, so
looking for feedback. The 3D model will be placed on the Files list
soon, along with the 5 axis trunnion table.

Thanks in advance,
Allan