gantry size

[zachjowi]

I plan on making my cnc router's bed about 4'x8' and making it like this
http://www.cnczone.com/forums/attach...2&d=1132041208

how many supports/rows of supports would I need? also any ideas as to how tall this gantry is?

thanks

[zachjowi]

is there any general rules saying to have a support every 1 foot or something like that?

[project5k]

well i think that the point is to support the rails so that they dont flex, and by having the supports at regular intervals, it will stiffen the bed and everything... the real thing about it is that if your using solid rod, then i think you might get away with farther spacing between the supports, but where thier using hollow black pipe, i think that the more supports the better... the #1 worst thing that i can think of is having something flexing while its running... that just throws any kind of repeatability and or accuracy out the window...
if you wanna go 14 inches, or 8 inches i think you will probably be ok, but just be prepaired if you go farther between your supports, you may have some flex issues, depending on what you cut and how aggressive you are when doing it...