What`s in a name: Random Orbital vs. Forced Rotation

[Todd@RUPES]

I sometimes see confusion when describing the types various types of dual-action (DA) polishers, so here is a brief description of terms used to describe these machines.

Dual-Action (DA): Dual-Action refers to the movements created by this machine. The two (dual) actions are an orbital movement and the rotational movement. The orbital movement is created because the center point of the backing plate is fixed to an arm which is connected to the drive mechanism of the motor similar to how a bicycle pedal is fixed to an arm which is connected to the axle.

The second movement is the rotational movement (spinning) of the backing plate/pad. This is either a function of the momentum imparted on a bearing from the orbital motion or an internal drive mechanism.

Random Orbital DA Polishers (ROB-DA): The Random Orbital polisher could have as easily been called a random rotational DA polisher. The orbital motion of the machine is driven by the motor and is constant/fixed (subject to load). The rotational movement of the pad is created by momentum and is random in nature. The rotational speed of the pad is in a constant state of flux (per orbital speed)as the pad is subjected to different frictional loads. Popular examples of Random Orbital DA`s include the Griot`s Garage 6 inch Polisher, the Meguiars G110v2, and the Porter Cable 7424xp.

Forced Rotation DA Polisher- Forced Rotation Polishers drive both the orbital and rotational movements. They are linked together and the pattern created by this movement is fixed and not random. Because forced rotation DA polishers drive the rotational movement they tend to have more polishing power. The most popular Forced Rotation DA Polisher is the FLEX 3401 VRG.

[Concours.John]

Having more recently using the DA for correction I can see the benefits of forced rotation. I have always been a rotary user. I just have had a better feel for rotary. I can see with foam some benefits for this machine (forced rotation) though. It seems to be no different as an intermediate step between stepping up or down in the amount of correction needed no different than changing up pads and compounds, just another variable. It`s on my list of tools (flex).
I think the key is knowing what you are looking for on how fast the correction is taking place or working for you with any machine.