Rotary tattoo machines use an electric motor that physically drives the needle up and down where a standard two coil machines uses magnetism to move the needles. Some advantages a rotary style machine may have over traditional machines are that they often weigh less than standard machines. Because a rotary uses a single motor instead of two coils, and an armature bar assembly, they can weigh as little as half as much as a standard stamped steel frame coil machine. The lighter weight means that a tattoo artist can work longer at a single sitting.

Rotary machines are very simple to use and to setup, with no springs contact posts or armature bars to vibrate loose, weaken or wear out. Because of the rotary action, they are basically free from vibration and run actually silent. There are no clip cords. Rotary machines use RCA jack inputs to power them, which make them easier to plug in and manipulate.

Rotary machines run efficiently on the same voltage (about 5.75v to 7v) as a standard coil machine, so you don't need to buy another power supply. 

It also should definitely be noted that the rotary machine is causing much less pain to the customer than the coil machine due to the rapid movement of the needle. In addition, rotary tattoo machine cause less noise comparing with other tattoo machine, which creates the psychological perception that the tattoo will be less painful.

A rotary tattoo machine can be used both ways as either a liner or a shader, depending on the type of needle bar you select. This means that a tattoo artist can complete an entire tattoo, no matter how complex the design, using only one machine. By contrast, dual coil machines can be used as either a liner or a shader, but not both.

Rotary machines are a matter of preference. You’ll never know if one is right for you until you try one and decide for yourself.