linear rod/bearing size/strength

I saw these rods/bearings and want to know if it will be strong enough for me:

http://www.vxb.com/page/bearings/PRO...Systems/Kit659

I want to build a 4' x 2' cnc gantry router. So I figure 5 feet would be about right. It looks like these shafts would be only supported at the ends. Would they bend? are they strong enough if supported on the ends? Also would I need 1 or 2 of the bearing slide units on each side?

Looking to use the xylotex 269 oz stepper system. Sound sufficient?

would like to use that nice hitachi router cutting 1/32 - 1/4" plywood maybe some 1/8" g-10/fr4

Thanks for any help,

Tom Moorehouse

Yes, they will bend. Just about any unsupported shaft will bend, and even for a 30" span, you'd want at least 1" (25mm) or more to minimize it.

what would be an inexpensive to do my x axis then? any other suggestions? I have the 8020 stuff but i'm guessing at that size it would not work?

any other inexpensive sources or supported linear rods? Even these pushed my budget to the max. they have the 25mm size would that work at 60"? i'm guessing not now.

There is no inexpensive supported linear bearings. Especially if $70 is too much for your budget. A number of guys are now building torsion box supported rollerblade bearing routers with large spans. Mine is 60" http://www.cnczone.com/forums/showthread.php?t=1356

And these.
http://www.cnczone.com/forums/showthread.php?t=15139
http://www.cnczone.com/forums/showthread.php?t=14331

And this one with V bearings
http://www.cnczone.com/forums/showthread.php?t=15270