I was wondering, is there a way to get rid of backlash in a CNC (DIY)? I'm trying to plan out a small 12"x12" 3 axis machine, but i want my numbers to work out so each step is 0.001". But if i have 0.015" of backlash, i'll have to so some VERY tricky designing to keep this from being a factor.

You could try using spring loaded nut, or gear, like in some CD-ROM drives.

Heres some info:
http://en.wikipedia.org/wiki/Backlash_(engineering)
http://www.patentstorm.us/patents/6311576-description.html

Most CNC control software has provisions for backlash compensation. There's no such thing as any machine tool that has zero backlash. You have to compensate for it. As long as your backlash is roughly consistent throughout the length of the ballscrew, you should be fine using software backlash compensation.

most machines have anti-backlash nuts on the lead screws. These will remove most of the backlash.

http://www.hsi-inc.com/w_style_nuts.php

a example of one.

There is no way to get rid of all of the backlash, but it can be minimized to less than .001 using propper setup. The ideal setup would have bearings supporting the ballscrew at each end with a direct drive to the stepper motor or servo drive via a zero backlash coupling or a cogged belt.

lead screws can be adjusted to minimum backlash usually .020 or less, but will become tighter and require more torque to turn the more backlash that is taken out. Ball screws have minimal resistance.

The CNC software will compensate for any backlas that you may encouter. All CNCs use comp tables to make up for backlash and error, even ball screw machines have backlash on the larger machines.