Body Work & Auto Paint - The Beginner's Guide To Body & Paint Work: Part I

Save A Huge Wad Of Cash By Doing It Yourself.

Jim Rizzo Sep 1, 2009 0 Comment(s)
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•Before my entry into the publishing world I spent a considerable amount of time working behind the counter of a major East Coast paint and body equipment jobber. Those 11 years of nearly constant education left me with a pretty good understanding of the basics of paint and bodywork (at least for one who doesn't actually do it for a living). And though the materials used have changed considerably since those days, the basic process has stayed the same. That said, for me the experience gained was priceless, mainly because I was able to use what I'd learned on my own hot rod projects over the years (saving me a boatload of hard-earned cash). Now that I'm in the process of building a couple of hot rods, I thought this might be a good time to share some insights on homebrewed body and paint work.

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Just keep in mind that there are about as many techniques or procedures for tackling these chores as there are people doing them, and though some will find a bit of my advice questionable, what you'll read here is a combination of what I've learned from others and things I've learned from personal experience. And if I'm able to inform, and more importantly, motivate even a small number of you to at least give the process a try, I'll consider this compilation a success!

First And Foremost
Probably the most important fact that I'll express here is this: anybody can successfully prep and paint their hot rod themselves. That's right! You can do it! I'm thoroughly convinced that even with little or no previous experience, any of you can undertake this daunting task and end up with a paint job you can be proud of. It might not happen on your first try, but I'm sure it can be done, because I've done it myself with nothing more than verbal and written instruction-no "formal" training at all. I just picked up a few tools, pulled the car into the garage, and started beating, sanding, and spraying. And believe me, most of you are probably more talented than I, so you've got no excuse not to at least give bodywork and paint a shot!

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Now, I know there are some out there who are shaking their heads and saying, "What about tools and spray guns, and paint materials and such? That stuff's expensive!" Well, sure, some of it is, but there are plenty of inexpensive body and paint tools available to the beginner these days. Everything from entry-level spray guns to long-board and dual-action sanders are available from discount tool stores and catalog suppliers (like Summit Racing Equipment). And you know what? They're perfect for the novice, and as your confidence and skills grow, you can make the decision to upgrade your equipment at any time (though much of my body equipment arsenal still consists of bud-get-priced tools purchased years ago). And besides, what you spend on tools, you'll save in spades when compared to the $65-$100 per-hour labor charges and outrageous paint material costs you'd have to fork over to a professional shop! Plus, there's nothing like the feeling of satisfaction you'll get when asked who painted your car and you can honestly say-"me!"

While I'm on the subject of cost, I've recently been informed of (and a short time ago used with great satisfaction) Summit Racing's new Summit Racing Paint and Auto Refinishing System. The new product line includes top coat paints, activators, clear coats, primers, and paint reducers-all at a significantly more affordable price than comparable brands. When I say significantly, I mean it. With the Summit system one can get all the materials needed for a complete paint job for right around $300.00-compared to about $900.00 to $1,500.00-literally hundreds of dollars less than comparable materials purchased at the local paint and body equipment jobber-and from personal experience, it's high-quality stuff!

Now That I've Got Your Attention
A place to work and spray is another consideration that I'm sure you're thinking of about now, as well. Most folks have at least a one-car garage these days, and that's fine. I spent many a winter with one side of my car pushed up against the wall while I worked on the other side. And just between you and me, I've painted quite a few in a plain old home garage (or out in the driveway) over the years, as well (though that was well before the days of environmental correctness and nosy neighbors).

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Before we get too far, though, I feel it's my duty to inform you that along the way, you're more than likely to make a mess or two or three (this is where the extremely affordable Summit Paint System really helps protect the wallet), but don't let it get you down. Lord knows I've made more than my share of screw-ups. But I've learned valuable lessons from each and every one of 'em, and if you're willing to "learn by doing," you really will be pleasantly surprised at the results.

Tools, Equipment, And Materials Using the correct tool for the job is half the battle. There are some specialized pieces that are pretty much necessities (like a DA sander, hammers and dollies, and spray equipment), but as I've said earlier, between Summit Racing Equipment and others, you can get what you need to start for a surprisingly small amount of cash. So let's start out by putting together a little list of what you'll need to get started: The first thing (and something that I've almost taken for granted) is an air compressor. Now, if you don't already have one, this may well be one of the largest investments that you'll have to make, but it'll become (by far) one of your most prized workshop possessions (along with a MIG welder, that is). Compressors can be had for anywhere from $300-$2,000, depending on size and quality. My personal compressor is a 6.5hp, 60-gal, 10.2cfm-@-90-psi, 220-volt Campbell Hausfeld unit (from Summit Racing, of course). This baby is an extremeduty compressor (meaning it's rated for constant use) that's been way more than adequate for my needs and, as a bonus, it retailed for under $600 - a great price for a good reliable compressor!

At this point it's important that whatever compressor you have, or choose to purchase, make sure it produces enough air volume. That's volume, mind you-not pressure. Most air-powered body tools (grinders and spray guns especially) will use about 8-9 CFM (cubic feet per minute), so make sure the compressor you're considering produces at least 9 CFM. If you don't, you'll be spending a lot of time waiting for your compressor to catch up, as the tools will use more air volume than the compressor can produce! Another thing to consider is voltage. Compressors that operate on 110 volts work fine, but they burn a ton of electricity! A 220/240-volt unit ends up being a heck of a lot cheaper to run, and that's really something to consider in this day of high energy costs.

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The next thing (we might as well get the initial big-dollar investments out of the way) is a MIG welder. There are literally dozens of makes and models (as well as price ranges) to choose from, and they're priced anywhere from under $300 to well over $1,000. I use a Miller 180 with Autoset (that I'm extremely pleased with) for everything from welding patch panels to chassis fabrication (as an aside, I just picked up a new Diversion 165 TIG welder, another Miller of course, and I'm excited about learning to TIG-weld-but that'll be another story). Again, though the compressor and welder will add up to a substantial sum, due to the myriad of things they'll be used for, and their extended working life, they're two of the most indispensable items any car guy can have in his or her garage.

The dual-action sander (commonly known as a "DA") you'll need is an air-powered orbital sander. The most common is the 6-inch model, though many production shops use a larger, 8-inch model. The size designation actually refers to the diameter of the sanding pad and the sandpaper discs used with it. It's called a dual-action sander because the pad rotates two ways: while it's spinning on a central shaft (much like a wheel spinning on an axle), it's also moving in an orbital fashion. The combination of these two actions results in a much smoother surface with no galling, as you'll find with a single, circular motion like that of a body grinder.

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Speaking of grinders, there are plenty of situations that require their use. From grinding welds to grinding out fields of old body .filler, the single, circular motion of a grinder fitted with a coarse-grit disc makes quick work of chores like these. Grinders come in both electric and pneumatic versions, but you'll find that a 5-inch, pneumatic model tends to be the lightest, smallest, and most versatile (but they do use a lot of air to operate).

There are a couple more air sanders that'll save you lots of time and elbow grease hen doing bodywork. One is called a "jitterbug" and the other a long board," and the main function of these sanders is cutting body filler on large, flat surfaces. The jitterbug is an orbital-type palm sander that is available for use with sandpaper in either of two sizes: 32/3x9 or 4x8 inches. The long board is a straight-line sander-in other words, its pad moves back and forth in a straight line. Long-board sanders use "long skinnies," which is slang for sandpaper that's 2 3/4x17 1/2inches.

Hammers, dollies, and body files are a must for any type of metal-shaping or dent repair. There are many specialized types of both hammers and dollies, but most chores can be accomplished with just a couple of multi-use designs. As far as body hammers go, a general-purpose dinging hammer (a double-faced, flat-head design) and a general-purpose pick hammer (a single face on one end and a pointed shaft on the other) will do the job in nearly every situation. The same goes for dollies. Body dollies are used to back up the metal being shaped using a hammer. They're heavy blocks of hardened steel that come in various shapes and sizes. A general-purpose dolly usually incorporates three or four different contours into one tool, which allows for almost unlimited applications. Another handy design is the toe dolly. This design is a rather thick, nearly rectangular dolly with two straight edges and two rounded edges, each with a slightly different radius.

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Body files are normally larger and heavier than the standard metal file you're used to. The double-sided, flat files are used for filing and shaping metal, as you might imagine. Stepped flat files are called "slap files" and used as their name implies (slapping an area of sheetmetal backed by a dolly). They stretch shrunken metal, and highlight spots that need hammer-and-dolly work (though, honestly, this is one tool that I've yet to really master).

Next we'll be focusing on the shop airsupply system, compressors, and spray equipment. We've chosen to tackle this subject at this point because the air supply system is one of the most important shop systems you'll have to consider. Let's face it, even if your foray into paint and body work is a one or two-time deal, you'll flat always be using air tools of one sort or another-and you'll want those tools to work correctly and efficiently.

Air Supply Systems
Once you've chosen a compressor that fits your needs (remember, air volume is more important than maximum pressure) and have it permanently located and wired, the next step is the design of an air supply system. Now, when we use the term "air supply system," what we're actually talking about is a permanent arrangement of piping, water traps, air regulators, and connectors. How you configure your system will determine how well it works. From there you need to decide on what material you'll use for piping. Galvanized steel and copper are the most common choices. Another way to go is by using a Complete Garage Air Line Kit offered by Eastwood (eastwood.com). It comes with 100 feet of 1/2-inch nylon tubing rated at 150 psi, aluminum distribution manifold, compressed air outlet manifold, six straight fittings with Teflon on coated threads, four 90 degree elbows, one tee, twelve wall mount clamps, and a tubing cutter.

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Choices
Next, you'll have to make a choice on the inside diameter of the piping you've chosen. Pipe diameters, if too small, will cause resistance, and this resistance will mean a drop in line pressure. There are guidelines in this matter, and you should follow them to achieve optimum results. For 11/2-2hp compressors with 6-9cfm ratings, use 3/4-inch id pipe for all lengths. For 3-5hp compressors with 12-20cfm ratings, use 3/4-inch for lengths up to 200 feet, and 1-inch for lengths over 200 feet. For 6-10hp units use 3/4-inch up to 100 feet, from 100-200 feet use 1-inch, and for over 200 feet use 1 3/4-inch id. Another rule of thumb is that the standpipe (the main hard line off the compressor) should never be a smaller diameter than the compressor-outlet size, and it should always be connected to the compressor with a flexible line (to absorb compressor vibration).

Now, for those of you who are, for whatever reason, not planning on permanently plumbing your home shop (though, we can't understand why you wouldn't), pay attention to this: The whole reason behind plumbing the air system properly is to alleviate as much of a contaminant problem as possible. This is because the act of generating compressed air (no matter what size or horsepower compressor used) produces heat, and heated air produces condensation as it cools. This condensation will collect in the air lines (either pipe or rubber hose), and be propelled out of the outlet and through either your spray gun or air tool. Compressors (especially pump-types) use oil for lubrication.

The oil in the compressor crankcase will work its way up into the compressor's cylinders as it runs, contaminating the air being compressed. Now, this won't harm your air tools (in some cases it's beneficial), but oil in an air supply will surely ruin a paint job. This is why, number one, you have to have a good water/oil trap. And number two, it must be placed a minimum of 25 feet from the compressor! If the trap is any closer, the air will not have had time to cool, and will condense after it has passed through the trap! This means that whether you permanently plumb the shop, or opt to just use rubber air hose, you still must place your water trap a minimum of 25 feet from the compressor. In fact, if it can be farther than that, all the better!

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System Assembly
Okay, let's say you've decided what material your lines are going to be made of and the diameter of them, as well. Now it's time to plan the actual layout, and assemble the system. First you'll need to connect a short length of flexible hose between the compressor and the standpipe (the vertical pipe that's the first leg of your system). The "standpipe" should head straight up from the compressor outlet to just about ceiling height. There, you can locate your first elbow, and begin to route your "main line" horizontally along the wall. The main line should be angled downward (away from the compressor) so it makes approximately a 4-inch drop over the course of its entire length (so the condensed water droplets will flow toward your water trap/filter).

Along the way, you will need at least one "feed line." A feed line is the vertical line (that drops down from the main line) to which you'll attach your filter/trap and an air pressure regulator, as well as a quick-disconnect for your air hose. You can, as you route your main line, add as many feed lines as you wish. It's always convenient to have feed lines located on more than just one wall.

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When you do attach the feed line (or lines), the Ts placed in the main line must be pointed upward. You want to come up off the main line T-fitting with a short piece of pipe, an elbow, another short piece of pipe, another elbow, and then your feed line going down toward your filter/regulator and outlet. At the bottom of each feed line (below the filter/regulator) you'll want to install a ball valve or drain to purge the line of any water that hasn't tried to exit the line through the filter and been trapped.

Okay, now you've got a standpipe, a main line, and a feed line (or lines). So it's time to go back up to the main line and finish off piping the system. At the very end of the main line, you'll want to add what's called a "drain leg." The drain leg is located at the very end (and at the bottom of the slope) of the main line. The leg should run downward from the main line, and should be long enough to terminate and end up as the lowest point of the system. At the bottom end of the drain leg, install a ball valve which will be used daily to drain any residual moisture from the system.

Water/Oil Traps, Filters, And Pressure Regulators
Air filters and control units (traps and regulators) are necessities needed in any air-supply system. Each feed line should be equipped with both. Filters (or traps) are necessary to eliminate contaminants, and control units (regulators) manage the air pressure allowed to reach the tools or spray guns being used.

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Air filters and regulators are available in many configurations (believe it or not, I use a combination of a WWII vintage army tank fuel filter assembly as a water trap, and a Milton coalescing filter, another item from Summit Racing). They can be individual units or combinations. This explains the different terminology used in their descriptions. Basically, an air filter is just that-a cleanable or disposable filter cartridge enclosed in a metal or plastic container, and its sole function is to filter contaminants. A trap, though, is designed to collect and then purge water caused by condensation in the compressor and air lines.

A regulator is just that-a device that's sole purpose is to regulate the amount and pressure of the air exiting the feed line. When the two are combined into one, they become known as "air control units." Air control units can also be made up of more than just a moisture filter and air regulator. Some are also equipped with what are called "coalescing" filters. A coalescing filter is an extremely fine filter that has a primary function of filtering out fine oil mist and/or particles down to .01 microns. These filters (either alone or combined with an air control unit) are extremely helpful in situations where there is a high oil contamination in a system (like that of an extremely worn compressor).

There are also small air regulators and filters made nowadays which are specifically designed for attaching directly to tools or spray guns. These diminutive helpers are perfect for those who choose not to fashion permanent air supply systems, but rely upon the simpler "plug the old hose into the compressor and work away" method. The regulators are designed to thread onto the tool's air inlet and usually have a knurled knob connected to some type of ball valve. Some are equipped with miniature pressure gauges, and some not. Miniature filters are designed to be disposable, and are normally used for short periods of time (determined by the manufacturer). The most common of these are plastic spheres sold as either the MotorGuard D-12 or the Sharpe F-2. They work well, and I use them as added insurance on my conventional spray equipment and plasma cutter.

Desiccant Air Drying Systems
Though desiccant drying systems are more often used in professional production shops, they are also lifesavers for hardcore hobbyists or those with severe moisture problems. Here, we'll try and explain a bit about these systems on the off chance you might like to equip your home shop with one.

As we've said earlier, when air is compressed and its temperature increases, so does its capacity to hold moisture. As the hot, moist air travels through the air lines, it cools, allowing the moisture to condense. Filters, drain traps, and drain legs are effective for removing liquid. But for removing residual water vapor and aerosols, you'll need a desiccant drying system.

Some desiccant dryers use silica gel beads to absorb moisture. As the wet compressed air flows through the inlet of the dryer and down into the bed of desiccant, the silica gel beads soak up nearly every bit of humidity or moisture in the air. In fact, the air humidity can be reduced to a 40-degree dew point with the use of silica gel.

After the moisture has been removed, the dry air passes through a sintered bronze filter and out the outlet port. As long as the desiccant is replaced when it reaches its saturation point, the unit will continue to supply you with clean, dry, moisture-free air. As the desiccant becomes saturated with moisture, the dew point begins to rise. This is usually evident when the silica gel desiccant begins to change color. It's at this time that the desiccant will need to be changed. Some types of desiccants are designed to be regenerated by baking it in an oven to dry it out, though most are designed to be discarded and replaced.

Another type of desiccant material is called Activated Alumina, and it's a byproduct of the manufacture of aluminum. This product is used for the removal of water vapor, and can lower the dew point to 100 degrees below zero. It has a high crush-strength and is a low dusting material. The capacity of this material to hold water is slightly lower than silica gel, but it can be regenerated by baking and has been determined to work well in paint shops.

Hopefully, this information will help you to design and fabricate an air supply system for your home shop that'll rival that of a professional production shop. Just keep in mind, whether you plan on doing any type of auto body refinishing or not, a clean, dry supply of compressed air will add years to the life of any sort of air-operated equipment.

Well, that's about all I can't in this installment, so it looks like I'll have to continue in the next issue. I really hope this information is useful for ya. And again, please keep in mind that the most important aspects of this attempt at information sharing is that all of us can really accomplish a heck of a lot more than we give ourselves credit.

Sources

Miller Electric
Appleton, WI 54912
920-734-9821
www.millerwelds.com

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