Quote Originally Posted by awerby View Post
That design provides very little headroom. If all you're using it for is cutting shapes out of plywood, it could work, but it doesn't seem suitable for much else. You'd still have to provide a solid table for the extrusions to mount to, and a way of holding them down securely. If you use ball screws, you'll have to figure out a place to mount them; that design doesn't provide any that I could see.
That cnc uses rack and pinion with geared steppers. My modification will be to use ballscrews. I've yet to figure how to attach them. I'm waiting for some parts to arrive yet.