Quote Originally Posted by m_c View Post
Regarding the rails, I was actually reading about them the other day (can't remember if it was on HSM, CNCZone, or the Mach Forum!), and the general consensus is most hobby builds are majorly over engineered, as there was some big commercial machine running 15mm rails for the long axis. The only reason I was reading about them, is I've got plans for a new machine bubbling away in my mind, and linear rails are featuring.
Looks like we've been reading the same things. I agree that if you calculate based on the load ratings they seem plenty strong enough...I'm going to use them on my machine unless some >15mm turn up cheap on eBay. I think that's the reason most people use bigger, because it's what was available at the time on eBay.
You may need to watch out for the moment ratings, though for the size of your machine it should be fine, just space the rails out on each axis as far as you can.

(That's a bit vague I know, I can give some numbers/examples if required)