Yep Mach3 has backlash comp

Mach 3 Backlash Compensation - YouTube

You may also want to check out the mach3 forums as well, but........if you use an external motion controller, as opposed to the Parallel Port, you'll have to look at the documentation for your particular controller.

I'd also be looking at the diameter of your bit (unlikely) and whether the steps per is correct....0.015 is a lot of backlash if you're using ballscrews. Also make sure all your mounts and nuts to lead screws are tight.