I am looking to finally build a reasonably good CNC machine, to help build other projects, finally. Anyways, I am looking at these 2 different linear rails from alltronics.com..

I want to use them in a Z axis with 7 to 12" travel on a ballscrew... Moving a portercable router.. A normal size one, if that makes sense..

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Thompson Rod 28 inch with Two Pillow Blocks
Thompson rods in good used condition 28 inches long x 3/4 inch diameter. Each rod has two super pillow blocks made by Thompson bearing their model number SPB-12 the cost on these new is well over $200 each, limited supply.
04T020 Unit Price : $49.95

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Thompson Rail Extended type Rd10HL
Thompson Slide bearing p/n RD10HL-285 with two AccuGlide pillow bearings p/n CD10AAAH. We have a limited supply of these new 285mm long linear bearings, a generous layer of grease is included. Each AccuGlide block measures about 2.5 x 4 mm and is free to travel the length of the rail and more!
04Z023 $34.95

alltronics: http://www.alltronics.com/robotics.htm

I would like the Travel to be closer to 12"... For some reason I think 2 of the rd10hl would be easier to mount and align.. But probably only 6-7" of travel...