If I had to name a single product that has caused the most excitement and confusion among car appearance enthusiasts in the past ten years, it would have to be the Porter Cable 7424 Random-Orbit 6" Polisher. Its name alone is a huge source of confusion, as it goes by several different nomenclatures, including "PC" (Porter Cable), "DA polisher" (dual-action polisher), "ROB" (random orbit buffer), or any of its model variants, including 7334, 7335 or 7336. If you're interested in knowing more about any of these models, visit www.porter-cable.com.

The Porter Cable (PC) 7424 started life more than a decade ago as a sander for woodworkers. Much like custom car builders, fine furniture artisans sculpt a piece of furniture, stain it to a desired color, then spray it with multiple coats of clear polyurethane. To achieve the final finish, they wet sand, compound, polish and wax.

With the introduction of foam buffing pads into the woodworker industry in the early 1990's, it's not hard to see how the PC 7424 came into use on car finishes. Clearly, this is a hobbyist and detailer movement, as Porter Cable did not design and does not market their 7424 for use on automobile finishes. So, why is the PC 7424 so popular within the car enthusiast hobby? Let's explore the inner workings of the machine.

The term random orbit defines the action of the tool's head. Unlike a rotary buffer, that spins at variable speed on a stationary spindle, a random orbit machine operates by spinning the head (free-spinning) on a center spindle and running this spindle around an eccentric offset. I measured the net pad throw (side-to-side) at a generous 15/16 inch.

Some people have defined the PC 7424's tool action as "jiggling", but this is not the case. The head freely rotates on a bearing and orbits around the centerline driveshaft. Rotation is a free-wheeling action of the backing plate spindle caused by the orbiting head. This "dual-action" is where the PC 7424 gets its "DA" nickname.

The fact that the backing plate spindle is free-spinning is what allows Porter Cable to call their 7424 a random orbit machine. In practical terms, there's nothing random about the polishing action. At about one pound of constant, even pad pressure, the backing plate spindle of the 7424 stops spinning.

The PC 7424 most closely mimics circular hand polishing. Imagine being able to make 2,500 to 6,000 tight hand circles in a single minute and you'll have a pretty good idea of how the PC 7424 does its job. It works just like your hand, only at Superman speed! To put the beauty of this machine into complete perspective, it works 100 times faster than a buff athlete, but it never gets tired!

As long as I'm comparing the PC 7424 to an athlete, I should mention that it's also adept at more than one game. Given the appropriate athletic gear, the 7424 is a tri-athlete, excelling at polishing, waxing and buffing. With the proper brush attachments, it has also been known to tackle carpets and upholstery.

If you have previously owned a random-orbit car polisher that made a lot of racket, but did little else for your car's finish, you will appreciate why I call the PC 7424 an athlete. Most consumer "car polishers" don't have enough power, have a very small orbit (often less than 1/4 inch), and have limited accessories. The PC 7424 is the first machine to shatter these limitations.

BASIC FEATURES & OPERATION
The PC 7424 has a powerful motor for its size, yet it pulls a scant 3.7 amps at 110 volts. If you don't have a garage, you can run the PC 7424 off of your car battery using a 750+ watt power inverter. The tool uses a standard 5/16-24 spindle, so a lot of different attachments will fit.

In pictures, the PC 7424 looks larger that it is. It measures about 10 inches in length and weighs a tad less than 6 pounds with a backing plate and pad attached. A reversible side handle makes the PC 7424 very easy to hold and control, even when working on vertical surfaces. Use of the side handle is a personal preference. It adds a bit of safety, but people with large hands may find it just as easy to grip the machine by the head with a single hand.

The machine functions at 2,500 to 6,000 operations per minutes (OPM), controllable by a thumbwheel on the rear end of the machine. The OPM measurement is used instead of revolutions per minute (RPM) to distinguish the difference between orbits and center shaft revolutions. At 6,000 OPM, this machine is doing a lot of work.

The standard PC 7424 comes equipped with a single white foam polishing pad that is permanently fixed to a 5" baking plate (Porter Cable calls them back-up pads). The standard foam pad is great for general purpose polishing and waxing. Due to the replacement cost of Porter Cable's foam pad (p/n 54745), most PC 7424 owners quickly switch to a Velcro backing plate and Velcro backed foam pads.

Changing pads and backing plates is easy. You use the flat spindle wrench supplied with the machine to hold the spindle and rotate the backing plate counter-clockwise to loosen or clockwise to tighten. When tightening, it is not necessary to turn the backing plate more than 1/4 turn once it has initially seated. Do not over-tighten. Snug is just fine.

For safety reasons, Porter Cable recommends that the machine not be operated unless the pad is flat on the work surface. That means you both start and stop the machine while it is resting flat on the surface of the car. If you're not going to follow this safety precaution, please wear safety glasses.

To operate the machine, follow these simple instructions:

1. Your car must be freshly washed and dry. Do not buff on a dirty finish.
   

2. Work in an area with good lighting. Overhead fluorescent or halogen lighting is best.
   

3. Remove all rings, watches, bracelets, belts and other items that will scratch your paint.
   

4. Wear an apron to protect your clothing and the paint finish.
   

5. Adjust the machine speed to 3 or 4 on the thumbwheel. This is a good starting point.
   

6. With the machine switched off, apply a small amount of polish, cleaner or wax directly to the polishing pad. There are two good methods that seem to work. Squeeze out a complete ring of product about 1 inch in from the outside of the pad, or squeeze out an "X" of product across the pad.
   

7. Dab the pad in 3-4 spots around the area to be polished, cleaned or waxed to distribute the product.
   

8. Position the polisher flat on the work surface, get a firm grip and switch it on with your thumb.
   

9. Move the polisher back and forth (east/west) in a slow, sweeping motion, overlapping each pass (by 50% of the pad width) with the previous, and then switch your pattern to up and down (north/south).
   

10. It is not necessary to apply more than a pound of pad pressure. Allow the polisher to work under its own weight.
    

11. Use a clean pad with each product. Do not mix products on a pad. If a pad is not dirty, you may store it in a Ziploc baggie for future use. Be sure to label the baggie or the pad.
    

12. If a pad becomes caked with product, use a nylon or horsehair detailing brush to clean the pad.
    

Sounds pretty simple, doesn't it? It really isn't difficult. Within a few minutes of use, most people are very comfortable operating the machine.

BUFFING PADS & BACKING PLATES
It's possible to use a range of backing plates and pads with the Porter Cable 7424. Velcro backing plates are available in sizes ranging from 3 to 7 inches.

For proper and safe operation, the backing plate and pad combination must be balanced to the installed counterweight. The purpose of the counterweight is to dampen harmonic distortions (vibration) caused by the pad whipping around in its tight orbit. If the counterweight was not in place, you would not be able to hang on to the machine for more than a few minutes before your hand went numb.

In general, the 5-inch counterweight (p/n 874011) should be used with a 5-inch or smaller backing plate, whereas the 6-inch counterweight (p/n 699933) must be used with a backing plate larger than 5 inches. Weight is the true determining factor for the proper counterweight, not the backing plate or pad size. If your machine vibrates excessively, you may need to switch counter weights. You will need a Torx driver (size T15, not supplied with the machine) to swap counterweights.

While on the subject of weight and counterweight, the lighter the backing plate and pad combination the more efficient the machine will be. Some suppliers assemble backing plate and pad combinations that have no business being connected to the PC 7424. After several years experimenting with a variety of backing plate and pad combinations, I have concluded that a light weight, 5-inch, flexible backing plate used in conjunction with a 6- to 7-inch pad achieves the best results. Larger backing plates and pads apply too much torque on the motor and rob efficiency. Also, to improve safety (stuff happens!), it's best to use a pad that offers .75 inch or more foam clearance beyond the backing plate.

There is an almost dizzying selection of pads that can be attached to the PC 7424. Here's a quick run down on categories:

1. Flat Pads

2. Waffle Pads

3. "Tufted" Finger Pads

4. Contour/Variable Contact Pads

Advanced foam pads, including different variations of the waffle, tufted and variable contact pads were designed for use on high speed rotary buffers. I find some benefit in using contour pads for heavy repair work (cutting pad), but not enough to call them a significant advantage over flat pads.

Within each of these categories, you will find several grades of pad from coarse (heavy cutting pad) to very fine (waxing and final finishing pad), and sizes ranging from 3 to 9 inches.

The effective pad contact diameter for the PC 4724 is 5.5 to 6.5 inches. Pads must be matched to an appropriate polish to achieve the desired results. Don't try to use a fine hand polish with a cutting pad to remove heavy oxidation or swirl marks. It simply won't work.

I find that using a 5-inch flexible backing plate with 6- or 7-inch flat pads offers the best results. I discourage the use of coarse "cutting" pads (normally yellow) by inexperienced users due to the real potential of removing too much paint material or creating hazing in the paint.

SELECTING THE RIGHT POLISH
Most of the major polish manufacturers make a selection of abrasive papers, compounds, cleaners, polishes and glazes to meet varying polishing requirements. Here's a quick definition of polishing abrasives:

Abrasive paper or pad - An ultra-fine grade of sandpaper (1500 to 3000 grit) that can be used effectively to level a paint finish and remove imperfections. I mention sandpaper here because it is an abrasive, like all polishes, and it has its place in the polishing process.

Compound - A compound, often called a rubbing compound or a paint cleaning compound, is a cutting polish designed to remove heavy oxidation, some common forms of paint damage and defects, and the scratches created by fine sandpaper. Use compounds with a foam cutting pad. Always start with the least aggressive pad and compound possible.

Polish - A specially formulated blend of components designed to remove minor scratches, surface imperfections, water spots, acid rain spots, light oxidation, and the swirl marks created by compounding with a machine. Use a foam polishing pad or a fine cutting pad.

Glaze - A very fine polish. Some glazes are safe to use on fresh paint, as they do not seal or contain silicones. A glaze does not have enough cutting power (if any) to remove imperfections, but will increase surface gloss. Use a fine foam polishing pad or a finishing pad.

Pre-wax cleaner - A fine polish containing chemical cleaners to help remove minor surface contamination and dirt not handled by normal washing or claying. Use a fine foam polishing pad or a finishing pad.

Each of these levels of polish can be used with a PC 7424, however, only a professional or very experienced user should undertake using the PC 7424 with abrasive papers or pads. Always follow the manufacturer's directions. Do not use a polish that is not specified by the manufacture (or a qualified source) for use with a dual-action machine.

A few of the larger polish manufacturers, who make paint polishes that work with dual-action systems, include: Meguiar's, 3M and  Mothers.  There are dozens of polish manufacturers, so I won't attempt to mention them all.

MAINTAINING & IMPROVING PAINT GLOSS
It is polishing, not waxing, that offers the most improvement in the overall appearance of paint. If you wax over bad paint, it's still bad paint. When you polish bad paint (paint with scratches, heavy oxidation, swirl marks, stains, water spots, etc.), you remove the bad paint to reveal a fresh finish. Obviously you can only do so much polishing before you wear out (thin or completely remove) the paint, so only polish as much as necessary to maintain healthy paint.

Buffing pad and polish makers create products with different levels of aggressiveness to make your polishing tasks faster and easier. You can use an aggressive pad and polish combination to quickly remove paint defects or severe oxidation, but it won't reveal the full gloss potential of your paint finish. Just like polishing a jewel, you must use several grades of polish to bring out the final radiance.

If your paint is new or like new, it is not necessary to use heavy abrasives. You can use very mild pre-wax cleaners and glazes to maintain the factory finish or create a finish that glows like a gem. To do so, use a fine polish and a foam polishing pad, and work the polish in with a light touch until most of the polish residue is gone. Remove the remaining polish residue with a quality buffing towel. Fine polishes won't take a lot of heat before they cake up and clog your pad, so don't apply pressure to the machine. Allow the pad and polish to do the work.

Some polishes respond well to a microfiber buffing bonnet, while others do not. If you're using a polish that is not buffing out clear, try doing the final buff out with a microfiber bonnet over a clean pad.

Here's how I use my PC 7424 to keep my paint looking new:

REMOVING COMMON PAINT DEFECTS
If you allow the paint finish to degrade from oxidation, water spotting, acid rain damage and other environmental hazards, you will need to remove the damaged paint to restore the finish. Even if you meticulously care for your car, sooner or later we all get paint defects. Polishing removes a very thin layer of damaged paint to reveal fresh paint and a restored finish.

The PC 7424 is an effective tool for removing most paint defects, including surface scratches, swirl marks, sanding marks, water spots, chemical etching, oxidation, scuffs and paint transfer. All of these problems are addressed in essentially the same way.

You start by using a cutting pad in conjunction with a fine rubbing compound to remove just enough paint material to cut away the imperfection. I have always found that removing about 90% of the imperfection in this step is plenty. Leave a bit for the final buff out, or you'll remove more paint than necessary.

After compounding, you switch to a polishing pad and a gloss enhancing polish (often called a "swirl remover polish") to remove the hazing or light dulling caused by the compound. This step will remove the remaining 10% of the imperfection, and reveal smooth, healthy paint.

Be very careful compounding and polishing on heavily oxidized paint until you know how much healthy paint is remaining. You could find yourself removing too much paint, creating thin spots or worse. If you over-buff an area of paint, you will completely wear away the clearcoat or color. The only repair for this mistake is to have the panel repainted.

You may find that you have to polish an area several times, and with a couple different polishes to get results. Don't get discouraged, this is not uncommon. Slow progress is better than rapid progress when it comes to paint polishing.

If you have a small area with deep damage that the PC 7424 cannot remove, you have a couple of choices: you can polish by hand using a heavy rubbing compound, you can wet sand with 1500 to 2000 grit paper, you can switch to a rotary buffer and a cutting polish, or you can live with the improvement you made.

POLISHING SECRETS
Machine polishing is messy. No matter how skilled you become, the machine will always sling off polish. To avoid a huge clean up job, I recommend using an old bed sheet to cover areas of your car that you don't want splattered with polish. This little step will save you a lot of clean up work.

Polishing can be quite detrimental to trim. If you need to polish close to trim, I recommend masking it with painter's masking tape. If you run your polisher against black plastic trim, rubber seals or brushed aluminum trim, you run the risk of ruining the original matte finish. Masking around window trim, door handles, windshield washer nozzles, antenna masts, door guards and other trim will reduce your clean up work and save you a lot of heartache from mistakes. Be safe; take the time to mask off your trim.

I like to prime a fresh, clean pad with a shot or two of detailing spray. Doing so makes the initial buffing a little smoother. Use just a light mist.  Don't drench the pad.

When your pad becomes caked with polish, use a small nylon or horsehair detailing brush to gently remove the polish. This must be done with the polisher switched off. I like the horsehair brushes the best, as they don't seem to rough-up the pads as much.

A dual-action polisher and a rotary buffer work polishes very differently. Using a rotary buffer to compound a car, you would run the buffer at a speed range from 500 to 800 RPM. The size of the pad, the torque of the motor, and a little pad pressure generate the right amount of heat to cut, break down the polish and bring up paint gloss. With a dual-action polisher, pad speed generates the energy necessary to get results from the polish. So, you have to turn the speed up on the PC 7424 to remove defects.

PAD & PC MAINTENANCE
The PC 7424 is a low maintenance machine. Porter Cable recommends yearly lubrication by a qualified repair center. If you use the machine professionally, I would follow the manufacturer's recommendation. For the typical enthusiast, sending the machine in for lubrication every three of four years should be sufficient.

There are varying opinions on pad cleaning techniques. Not long ago, the pad manufacturers themselves would tell you not to wash the pads, as the water and detergent would de-laminate the Velcro from the foam. For the most part, this seems to be resolved.

If you are a professional detailer, washing pads after each use would be very time consuming. The best solution for the professional is to keep pads brushed clean and store them in large Zip-lock baggies. Mark the back of each pad with a marker to indicate which product is on the pad. When the pad becomes too dirty to use, wash it.

Do not wash pads in the washing machine. They must be hand washed. To do so, simply add an ounce of dish washing detergent to a 5 gallon bucket and fit it with water. Soak the dirty pad for up to 30 minutes. After soaking, massage the pads to work out the caked in polish, then squeeze out the soapy water. Empty and refill the bucket with fresh water. Rinse the pads in the bucket of fresh water, squeeze, and set aside to air dry. Do not machine dry.
 

PRACTICE MAKES PERFECT
While the PC 7424 is a very easy polisher to master, practicing on an older car with an imperfect finish is the best way to learn. You should experiment with a variety of polish and pad combinations until you learn how to achieve the best results.

There is no silver bullet combination of pads and polish. How you use the machine, your climate, paint hardness, paint color and other issues will all factor into the final results. Don't get frustrated if your initial experience is not perfect, as the smallest change (a different pad, polish or speed) can make a huge difference.

SUCCESS STORIES
Here are a few before and after pictures of vehicles with severe paint damage that were restored using a Porter Cable 7424.