Even operating a DA Porter-Cable, there are indeed, methodology/technique "tricks" to its use, as you found out the hard way. Here`s my PC-newbie list of common-sense usage:
1) Before connecting the PC electrical cord connector to at least 12 Gauge-wire extension cord, check that the PC switch is in the OFF position. Sound easy, but it is much easier to forget, especially if the extension cord and PC cord come apart, for what ever reason.
2) Drape/wrap the electrical cord over your shoulder so the cord does not rest against he paint of the vehicle as you move over it, like the hood or roof.
3) Tie a knot between the extension cord and the PC cord to prevent the electrical connectors from coming apart OR (better) buy a cord-connector tie and use it.
4) When setting it down with the pad on it, try not have it flop over onto the pad and pick up any contaminants that may scratch the paint as you continue to polish. If it does, clean that pad, or use a new or cleaned pad of the same type.
5) If the PC seems to vibrate too much, shut it off and re-center it on the backing plate. Even a slight mis-centering can cause a lot of vibration.
6) Do not overuse a pad for any length of time. Too much heat will literally melt the Velcro adhesive and cause the Velcro to delaminate (separate) from the pad. You will learn this the hard way when one flings across the vehicle as you are working and slightly lifting the PC from the surface.
7) Do not put too much pressure on the pad. Rather, let the weight of the PC, the pad itself, and the compound/polish do the work of removing the scratches and swirls. If you do, the oscillation/rotation of the PC is defeated or "stalled", and the cutting motion is negated. What you will have to do is to: a) stop and wipe off the compound/polish, b) add additional compound/polish to the pad, and c) go over that area again. This may need to be repeated 3 or 4 times before an area is corrected completely. It is just a working limitation of the PC and its motion.
8) Add a 1/4-20NC X 3/8" long hex-socket head cap screw to the OPPOSITE SIDE tapped hole of the PC where the single-grip handle extension connects IF you are using such a handle. It helps reduce the PC vibration. Just make sure it is fastened tightly in the tapped hole.
