As with any other work, many factors limit the autobody metal repair and fabrication projects that you attempt and your results. These include your skills and organizing abilities, and the limits of the materials and processes that you employ. Just because you want to repair something or wish to fabricate some shape, does not mean that it can be done or, more important, that you can do it. These are limits that you have to discover.
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A good first step in organizing any project is to visualize how you and your resources best plug into it. Anything can seem difficult and intimidating the first time that you do it. You may worry over all of the various things that can go wrong. Later, after you have successfully done it, you will have the confidence to know that you can overcome whatever problems it presented. As you go further in autobody metal work, your confidence level will increase, and so will the difficulty of the jobs that you are comfortable attempting.
After you master several different aspects of this work, you will realize that many complex jobs that at first seemed between difficult and impossible become possible when you break them down into specific tasks that you are pretty sure you can successfully complete.
Before you get to that point of knowing that your knowledge, skills, and judgment are up to a job, you have to be certain that your materials, processes, and procedures also are up to it.
The limits of inferior and/or inappropriate materials can haunt and destroy your best intentions and most ambitious jobs. Take sheet-metal, for example; it is available in many places and for many prices. If you want to buy a large amount inexpensively, just go someplace where someone is removing an old tin roof. You can buy the rusty, dented old roofing for the proverbial song.
But there are problems with using roofing tin in autobody projects. It is too thin for most fabrication and repair jobs and its carbon content is higher than is desirable for automotive work, making it harder than hammered owl poop. And that is when it is new. If you try to make a fender patch out of a salvaged bit of this stuff, you can add the problems of rust, denting, nail holes, and work hardening to the list of problems.
“Ah-hah,” you might say, “But my local plumbing supply store sells 26-gauge double-galvanized HVAC duct tin in 4 x 8- and 4 x 10-foot sheets, and it’s pretty cheap, figured by the square foot.” Sorry, but you knew that I was going to rain on that parade. HVAC duct tin tends to be too soft for autobody repair or fabrication work, and 26-gauge is decidedly too thin for it.
There is also sheet steel sold in various thicknesses at hardware stores and lumber yards. It isn’t inexpensive, but it comes in different sized sheets, and says “weldable sheetmetal” or something like that on the sticker that states it size, gauge, and universal price code. In fact, this is definitely closer to metal that you might be able to use for autobody work. At least it comes in reasonable gauges for that use, and may have characteristics that are fairly close to those that are desirable for autobody panel work. The problem is that it is specified for a wide range of hobby and homeowner projects, and probably lacks the very specific and necessary characteristics for first-class automotive work.
The best way to acquire good sheetmetal for autobody metal projects is to look for it in places that specialize in supplying the autobody trades. Body shop supply outfits usually have a line of sheetmetal, in a few different gauges and specifications. At least this metal is intended for the purpose for which you are going to use it. And, consider this: These suppliers rely on repeat business from body shops for their livelihoods. If they supply products that are bad for the purposes for which their clients buy them, they tend to lose customers and cease to exist. There are also mail-order companies that supply panel steel to the autobody and panel-fabrication trades. It is usually pretty good metal for those purposes.
Another intriguing source of panel steel for some projects is auto-motive salvage yards. If you need a particular crown or configuration for part of a fabrication, or for a repair patch, you often can find something close to the shape that you need, incorporated in the decklid, door, or fender of some unrelated salvage panel. If that panel isn’t too rusty or damaged for your use, you can buy it and cut out what you need. You never find the perfect item for what you need, but it is often much easier to modify an already stamped section of a panel to exactly what you do need than it is to start from scratch with virgin flat stock. I know many metal workers who keep a supply of salvage panels around, just in case.
In general, the same rules that apply to acquiring good-quality panel steel apply to most other supplies that you will use in this work. Things like welding supplies, filling supplies, and fasteners should be high-grade items that are intended for automotive work. Using the cheapest versions of these things that are sold to the general public does not result in top quality automotive work. Off-brand soldering supplies, or welding rod and wire, may be perfectly okay or they may be junk. The small amounts of money that you save by buying this stuff are not worth the risk of messing up a project by using it. There are enough inherent problems in this work that are difficult to predict, without taking chances on the materials and supplies that you use.
Even when you buy what are supposed to be top-quality materials and supplies from reputable vendors, it is always a good idea to test them, to see how they perform when you use them in an application. If something is not going to work well for you, it is best to know that before you commit to using it.
If you find a new source of sheetmetal, welding wire, or rod, try it out, experiment with it. Pound the metal into various shapes to see how it reacts to various processes, like hammering, power hammering, and wheeling. With welding supplies, make trial welds. See if you get good bead formation and penetration. In the end, you will benefit from using only those materials with which you are comfortable.
You should remember that no single material or supply is likely to be ideal for everything that you do with that class of material or supply. Sheetmetal of different specifications, and from different sources, works best in some specific applications, and not as well in others. Some welding supplies are fine for one type of job, but less desirable in other applications. When you evaluate new materials and processes, you should keep this in mind and remember what works best in which circumstances, and for what purposes.
Considerations similar to those governing the limits of materials, supplies, and procedures apply to your own skills and to your equipment. In some cases these will be adequate for particular projects and in other cases, without upgrading them, they will not. Fortunately, in autobody metal work, most people engage in the continuous improvement of their skills, tools, and equipment.
One great resource that can be yours without any investment in tools and equipment is planning your jobs. This sounds simple, and for the most part it is. However anyone can let a job progress with little or no advance planning, and end up with uncertain results. Take two separate examples: repairing a rust-out and repairing a dent. You can plan these jobs minutely, probing the extent of the rust-out and analyzing the nature of the dent. Then, you can formulate the best and most efficient ways of dealing with these jobs.
In the case of the rust-out, this involves welding in enough new metal to do the job completely, and so that it will be durable, while avoiding excessive heat buildup and resulting distortion in the panel. In this case, that means keeping the repair area to the minimum necessary size to get it done with a good result. In the case of the dent, accurate analysis allows you to move the least amount of metal that completely unlocks the undamaged metal configured into the dent. This results in the least possible collateral damage to adjacent metal from stretching and deforming areas that do not really need to be worked.
The alternative to this kind of planning is to throw yourself, willynilly, into a job and let one move dictate the next, with little or no planning at all. Sometimes, this happens when a job seems so simple that it doesn’t require any planning. Often, this approach results in letting one mistake or miscalculation dictate the next, as the job careens toward disaster. It sounds pretty dumb, but we have all been there, in one way or another, and I claim no exception to that dubious distinction.
Of course, it is possible to over analyze or overplan your work, to the point that these approaches become paralytic. Then, all that you can see are cascades of hypothetical problems, leading to catastrophe. Good planning in body metal work stops short of that kind micro planning, but goes deep enough to avoid most foreseeable problems.
There are certain propositions in bodywork that amount to inherent advantages in the nature of this work that you can leverage for your benefit. Here are two simple ones: Auto-mobiles are mostly bilateral, and you can only see one side of a vehicle at a time.
you have no pattern. With a panel like a badly damaged hood or roof, you still can determine its proper final shape because you have the other side for a model. Of course, you have to translate the measurements of the good side into its mirror image, but this is not always difficult. For example, if 5 inches back from its front, the outer edge of a hood falls 13⁄16 inches from the high point at its center, it should do this on both its right and left sides. When you are removing a dent from it or sectioning in a rust repair, this kind of information is priceless. Of course, you usually have to plot many points this way for this trick to be useful.
When you inspect your progress restoring that hood, you can use that measurement, and numerous similar measurements, to know how to proceed in the job, and to confirm when you have it right. The bilateralism and symmetry of the hood informs your eye when the panel is right, but the use of bilateral measurements helps you to get there. In some cases, translating bilateral measurements enables you to build models of shapes that you need to fabricate from scratch.
The inherent advantage of vehicle bilateralism does not end with symmetry, but couples with another inherent advantage of vehicle configuration that may make your work easier. You cannot see both sides of a vehicle at the same time, unless, of course, it is parked alongside a mirror, or some other perfectly accurate reflecting surface, which is extremely unlikely.
The fact that you can only see one side of a car at a time can be an enormous advantage if you have to fabricate, or massively repair, an item like a fender or fender skirt. You can use the fender skirt from the other side to translate and create a pattern for the one that you fabricate. In this case, the final fit of the fender skirt has to be to the metal on the side where it belongs. But patterning from the other side will get you started on the shape. After you have made the actual piece, and blended it to the metal on the side where it will be used, it may not exactly match the one on the other side from which the pattern was created. That is not a problem because, after they are mounted, you never see or compare the two fender skirts at once.
This brings up another point about human perception. People often tend to see what they expect to see. About 90 percent of all lightning strikes originate from the ground upward. But we tend to see it as striking down. Why? Because we expect to see fast-moving things fall out of the sky, not rush up into it. The same rule of perception applies to bodywork. People expect to see most panels formed into smooth arcs and contours, with sharper arcs, creases, or angles at their ends, and in some other areas. If you are able to make metal work into those arcs and creases with reasonable but not necessarily perfect accuracy, your work will pass visual inspection.
This is not an invitation to do sloppy work that meets the low standard of close enough. It is simply recognition of the reality that the human eye does not see things with perfect dimensional perception of accuracy.
Divide and Conquer
Most bodywork jobs can be divided into tasks and subtasks. In many cases, these can become routine. What looks like an incredibly difficult repair, or a massively challenging fabrication, often can be approached this way, as a series of simpler tasks. For example, faced with having to create a complex fender patch to repair a rusted or hopelessly damaged area, the job can look impossible at your skill and equipment levels. But when the piece that you need to fabricate is analyzed for its exact content, you may discover that simpler tasks that you have mastered will add up to its completion.
Let’s say that this section of an old fender has some crown, a dropped edge with a narrow bead, and a wire folded under the edge of the bead. That looks intimidating.
But by using body hammers and mallets, you can form the body of the repair area on a shot bag, or on a wooden form that you create for that purpose. You can model and cut metal into the shape of the edge and you can wrap it around the edge wire. Then, you can align and weld the folded bead area to the larger piece that you have made. Sure, it’s simpler in the telling than it is in the doing. But the fact remains, this seemingly complex job can be divided into areas and tasks that are relatively simple, and then assembled into a finished piece that is complex.
Would it be better to make the section described above in one piece? Probably it would. And someday you may have the experience, skill, and equipment to do that. But before that day arrives, it is good to know that you can build complex shapes out of simpler ones that are already within your competence. Later, when you achieve great expertise and proficiency in this work, it will be fun to remember the cumber-some approaches that you once had to take to do jobs that you can now do much more simply and much better.
Written by Matt Joseph and Posted with Permission of CarTechBooks