not. Fortunately, in autobody metal
repair
area
to
the
minimum
Of course, it is possible to over-
work, most people engage in the con-
necessary size to get it done with a
analyze or over-plan your work, to
tinuous improvement of their skills,
good result. In the case of the dent,
the point that these approaches
tools, and equipment.
accurate analysis allows you to move
become paralytic. Then, all that you
One great resource that can be
the least amount of metal that com-
can see are cascades of hypothetical
yours without any investment in
pletely unlocks the undamaged
problems, leading to catastrophe.
tools and equipment is planning
metal configured into the dent. This
Good planning in body metal work
your jobs. This sounds simple, and
results in the least possible collateral
stops short of that kind micro plan-
for the most part it is. However any-
damage to adjacent metal from
ning, but goes deep enough to avoid
one can let a job progress with little
stretching and deforming areas that
most foreseeable problems.
or no advance planning, and end up
do not really need to be worked.
with uncertain results. Take two sep-
The alternative to this kind of
Inherent Advantages
arate examples: repairing a rust-out
planning is to throw yourself, willy-
and repairing a dent. You can plan
nilly, into a job and let one move
There are certain propositions in
these jobs minutely, probing the
dictate the next, with little or no
bodywork that amount to inherent
extent of the rust-out and analyzing
planning at all. Sometimes, this
advantages in the nature of this work
the nature of the dent. Then, you
happens when a job seems so sim-
that you can leverage for your bene-
can formulate the best and most effi-
ple that it doesn’t require any plan-
fit. Here are two simple ones: Auto-
cient ways of dealing with these jobs. ning. Often, this approach results in
mobiles are mostly bilateral, and you
In the case of the rust-out, this
letting one mistake or miscalcula-
can only see one side of a vehicle at
involves welding in enough new
tion dictate the next, as the job
a time.
metal to do the job completely, and
careens toward disaster. It sounds
That means that their left and
so that it will be durable, while
pretty dumb, but we have all been
right sides are, or should be, mirror
avoiding excessive heat buildup and
there, in one way or another, and I
images of each other. And that can be
resulting distortion in the panel. In
claim no exception to that dubious
a huge advantage when you have to
this case, that means keeping the
distinction.
repair or fabricate a shape for which
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
23
CHAPTE R 2
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 strik-
ing down. Why? Because we expect to
see fast-moving things fall out of the
This fender skirt illustrates the bilateralism of auto bodies. The one on the
other side of this Packard is a mirror image of this one, and can be used to
of perception applies to bodywork.
pattern it. In this case, absolute bilateralism is not necessary because you can
People expect to see most panels
never see both fender skirts at once.
formed into smooth arcs and contours,
with sharper arcs, creases, or angles at
you have no pattern. With a panel
translating bilateral measurements
their ends, and in some other areas. If
like a badly damaged hood or roof,
enables you to build models of
you are able to make metal work into
you still can determine its proper
shapes that you need to fabricate
those arcs and creases with reasonable
final shape because you have the
from scratch.
but not necessarily perfect accuracy,
other side for a model. Of course, you
The inherent advantage of vehicle
your work will pass visual inspection.
have to translate the measurements
bilateralism does not end with symme-
Put bluntly, some of the best
of the good side into its mirror image,
try, but couples with another inherent
bodywork that you are likely to see
but this is not always difficult. For
advantage of vehicle configuration
would never pass a close dimen-
example, if 5 inches back from its
that may make your work easier. You
sional inspection with calipers, dial
front, the outer edge of a hood falls
cannot see both sides of a vehicle at
indicators, or laser scanning. Fortu-
13⁄16 inches from the high point at its
the same time, unless, of course, it is
nately, that is not a problem because,
center, it should do this on both its
parked alongside a mirror, or some
after it leaves the factory, it doesn’t
right and left sides. When you are
other perfectly accurate reflecting sur-
have to pass that kind of rigorous
removing a dent from it or sectioning
face, which is extremely unlikely.
dimensional inspection.
in a rust repair, this kind of informa-
The fact that you can only see
This is not an invitation to do
tion is priceless. Of course, you usu-
one side of a car at a time can be an
sloppy work that meets the low stan-
ally have to plot many points this
enormous advantage if you have to
dard of close enough. It is simply
way for this trick to be useful.
fabricate, or massively repair, an item
recognition of the reality that the
When you inspect your progress
like a fender or fender skirt. You can
human eye does not see things with
restoring that hood, you can use that
use the fender skirt from the other
perfect dimensional perception of
measurement, and numerous simil
ar
side to translate and create a pattern
accuracy.
measurements, to know how to pro-
for the one that you fabricate. In this
ceed in the job, and to confirm when
case, the final fit of the fender skirt
Divide and Conquer
you have it right. The bilateralism
has to be to the metal on the side
and symmetry of the hood informs
where it belongs. But patterning from
Most bodywork jobs can be
your eye when the panel is right, but
the other side will get you started on
divided into tasks and subtasks. In
the use of bilateral measurements
the shape. After you have made the
many cases, these can become
helps you to get there. In some cases,
actual piece, and blended it to the
routine. What looks like an incredibly
24
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
LI M ITS OF MATE R IALS, EQU I P M E NT AN D S K I LLS
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 equip-
ment 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 mas-
tered 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
Forming the new metal to section in rust repairs for this fender is a complex
repair area on a shot bag, or on a
job, but it can be broken down into multiple simple tasks. Always consider
wooden form that you create for that
approaching complex jobs as several simple tasks.
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 sim-
ple, and then assembled into a fin-
ished piece that is complex.
Would it be better to make the sec-
tion described above in one piece? Prob-
ably it would. And someday you may
have the experience, skill, and equip-
ment 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 com-
petence. Later, when you achieve great
expertise and proficiency in this work, it
Always record the exact construction of panel areas that you need to replicate.
will be fun to remember the cumber-
Written notes and photographs may help enormously, after you have cut out
some approaches that you once had to
and destroyed original sections of these panels. Without good records, what
take to do jobs that you can now do
seemed easy to remember may become difficult as time passes.
much more simply and much better.
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
25
C H A P T E R 3
TYPES OF JOBS
This chapter looks at the core tasks
the mid 1930s, this information was
used in damage and rust repair jobs,
issued as a booklet of a little more
and at some of the most basic strate-
than 100 pages, titled The Key to
gies and skills needed to master them.
Metal Bumping, by Frank T. Sargent.
What you need to know starts here.
In various formats, this book has
been more or less continuously in
Damage Repair
print since then, with reprints of the
1953 edition still available.
The analysis of crash damage is
That book revolutionized auto-
the first and often most critical step
body repair by putting theory under it,
in repairing it. Before the 1930s,
and by specifying a series of standard
there was little or no literature avail-
procedures to guide it. It is, simply, the
able to indicate standard operating
Holy Grail of sheet steel repair practice.
procedures for this crucial first step in
While much about the autobody crafts
repair. While some practitioners—
has changed in the more than 75 years
body and fender men—may have
since The Key to Metal Bumping was first
had fairly modern approaches to
published, everything in it is still accu-
repairing deformed metal, most of
This reprinted version of the 1953
rate, relevant, and useful. Anyone seri-
them did not. They simply hit metal
edition of The Key to Metal Bumping
ously pursuing the sheetmetal craft
with hammers against dolly blocks
is still available today. Its advice
should examine a copy of this trove of
and hoped for the best, and that
regarding the basics of analyzing
body panel wisdom.
everything would come out right. If
collision damage and moving metal
The nugget of The Key to Metal
metal was high, they hit it down. If it
remains clear, to the point, and useful.
Bumping is that body damage con-
was low, they hit it up. In this
sists of direct and indirect compo-
process, they often inflicted terrible
company issued catalogs that con-
nents. The first is deformed metal
additional damage to metal, like
tained the first easily accessible sci-
that is displaced beyond the elastic
stretching it and cracking it, but they
entific information on sheetmetal
limit of the panel material, and that
managed to hide this damage under
repair. This methodical approach to
is holding the indirectly damaged
the filler material of that period, lead.
repairing damaged autobody panels
metal out-of-place. Relieve the direct
All of that changed in the early
revolutionized the craft and trade of
damage, the book advises, and the
1930s, when the Fairmont Forge tool
autobody repair. After a revision in
indirect damage will mostly spring
26
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
T YP E S OF JOB S
back into its proper place. This is
exciting because the area of indirect
damage usually greatly exceeds the
area of directly damaged metal.
Unlocking the directly damaged
metal is the key that enables you to
solve the repair puzzle, usually with
a great deal less intervention than
might first seem necessary.
The Key to Metal Bumping divides
direct damage into ridges, or outward
bends and V-channels, which are
concave, or reverse, ridges. Buckles
and rolled buckles (added later to the
damage vocabulary) involve metal
that has been forced out of place, by
surrounding metal as damage occurs.
The book suggests that all direct
damage can be described in the This damage is somewhat complex, and noodling the sequence of the event(s)
categories and characteristics of that caused it is of medium difficulty. Still, the time taken to work out a theory
V-channels and ridges. As with all
of that sequence is well spent when you have to remove damage like this.
great theories, author Frank Sargent
proposes a concept that is relatively
Here, The Key to Metal Bumping offers
becomes relatively easy to formulate
simple but that explains much. He
a tremendously useful and (for the
a plausible theory regarding what
suggests that if you look at what
time) revolutionary concept of how
deformed a panel, and in what
appears to be complex panel damage,
to look at collision damage. It
sequence. Please note that such theo-
you can reduce it to combinations of
advises examining complex damage,
ries do not have to be perfect, but
the items noted above, ridges and and figuring out the order in which
merely plausible and possible, to pro-
V-channels. With the addition of
the metal was deformed; that is, the
vide the basis for corrective action.
buckles and rolled buckles, this the-
sequence of events in the collision
Once a body practitioner has
ory becomes comprehensive.
that deformed it. Where was the
such a theory of damage in mind,
Sargent proposes a method of
panel first struck? Where did the
The Key to Metal Bumping advises
working out damage that employs
striking force go next? What effect
removing the damage in the reverse
the least use of force, a novel concept
did the deforming metal have on
order of how it was created. In other
at the time. Taking account of work-
adjacent metal, and how did that
words, you correct the last event in
hardening factors, he advises working
interact with the deforming force as