[zaid]

How to convert Manual Lathe to CNC Lathe, without purchasing kit if possible. I am new in this matter.

[Al_The_Man]

For one, you will need to replace the Acme screws with ball screws, there has been several past threads here covering the steps for the conversion procedure.
Al.

[mackeym]

You'll also need servo or stepper motors and a drive for each motor. It's good to have a servo spindle too, but this isn't a necessity.

[The Blight]

You dont need a servo spindle. What you "need" is an encoder so that it knows at what speed its turning. If you want to do milling jobs on the lathe with live tooling, you should consider making it sort of a servo with a break.

You can even do with regular Acme screws, but there are more friction in them, and they have more backlash.

Other then that, you will need (as mackeym allready pointed out) servos or steppers with drivers (one for each motor), and a powersupply. You will also need a breakout board for connecting the drivers to a computer.

[zaid]

Thanks, Al The Man, mackeym and The Blight for your replies. I have search the net for this and found following artical useful :
http://www.dakeng.com/CNCconvert.html
But I need more detailed, information for the same.