General Questions about CNCing??

[Hellbringer]

Hi,
i have 2 questions about cncing/machineing.

1. what exactly is backlash and what is it caused by?

2. if i converte a x2 mill is there a way to have the computer control spindel speed and when it turns on and off?

thanks mike

[Oldboy]

Backlash? If you look at a ACME screw on a X2 Mini Mill,Sherline Mill or just put a bolt in a nut for example.
Push it in and pull it out. The distance it moved in and out is the Backlash.
Now as it turns many times in and out. Things wear out-meaning more Backlash.
As for your other qestion.
The driver board you purchase would need to have control options.
And the motor you use to drive the end mills would have to ether send a signal of its RPM back to the driver board.
Or use large stepper motor to drive the end mills. Then you would not need that return RPM signal. Im going to use a large stepper for my 4th axis.
It will let me mill out Gears ect.