On Sun, 20 Feb 2005 21:02:09 -0600, stanley baer
wrote:

John Smith wrote:
I am planning to build a very large CNC plasma cutting table for cutting
plates of 6000x2000 mm metric, so about 20' by 7'
Anyone know which company supplies rails and screws that long?


I would use a timing belt drive, Brecoflex sells the most precise belts.
As for the rails, thk style rails can be bolted on end to end. I have
designed long feeding mechanisms in this exact fashion and the resulting
machine was able to hold tolerances under 0.010" atlthough a lookup
table might have been used for error compensation.

stan
Some cnc software has this option. You can use a laser or similar to
map the errors and tell the control where it really is.
ERS