I already worked on a 3d printer using arduino mega with RAMPS shield. It can only work with stepper motor and not with servo. Now, I am using a printer which has servo in it. I don't know what type of shield should I use. Can anybody tell me what can I use?
Usually you don't need a shield. Provided you have a separate supply for the servo, you can drive it directly from the arduino.
A servo has 3 wires and needs PWM signal. If I have 3 servos to connect, so how should I wire them.
vipulkumar731: A servo has 3 wires and needs PWM signal. If I have 3 servos to connect, so how should I wire them.
Take a look at the servo library page you can find examples there. Or take a look at the examples of the Arduino IDE. Even if the examples control one servo only, it is possible to control more than one servo at the same time.
Hook the power wires to power and the ground wires to ground and the control wires to whatever i/o pins you want.