Long X-Axis w/o leadscrews

[Jerry In Maine]

I have a home-brew cnc router now with a x-axis lead screw that's about 3' long. It works, but I'd like my next machine to have a longer bed and I'd rather not rely on a screw-drive. I'd rather go with a belt drive or other similar solution. My experience have show long lead screws are prone to whipping at fast feed rates amoung other problems...

Anyone hve any alternate suggestions of a means to drive the X-Axis that would be accurate enough for wood working (and v-carving) but still affordable on a hobby budget.

Any references to any web pages showing drawings or other illustrations?

Thanks -

[TSJ]

At a recent wood show I saw a machine that the "X" axis was driven by a ball screw on each side, the screw was at least ten feet long and probably 1 1/2 in diameter. To help the "whipping" they had a device that would steady the ball screw placed at about three feet from each end. The device had a plastic fork that would ride on each side of the ball screw, it had three fingers equally spaced at 120 degrees. As the gantry came by it would hit the finger touching the ball screw and the finger would rotate out of the way until it would clear the gantry and the next finger came up behind the gantry. With this device the ball screw always had support approximately every three feet. Just another idea...

[blerik]

You could try a linear actuator from nanotec.de. They look like a servo with a hole in the axle. The hole is actally the nut, the actuator rotates it directly. This means that the leadscrew itself can stay stationary, so no whipping.

--Blerik

[Greolt]

Consider Rack and Pinion. Many comercial machines use this.

More economical than large diameter ball scrrews.

Take a look at the pictures on this site

http://www.mechmate.com/

And this is my build log if you are interested.

http://www.cnczone.com/forums/showthread.php?t=28979

Absolutely accurate enough "for wood working (and v-carving)"

Greolt