by Matt Joseph
tions against the backs of fenders,
The two rawhide mallets (lower left)
they are also used as hammers. Most
provide soft, yielding surfaces for
dollies are made of cast iron, and pre-
Hammering off-dolly is a precision
moving metal. The lower one is shot-
sent several different and useful con-
operation that is used to shape metal
filled, giving it a dead-blow feature.
tours for working surfaces. When
without stretching it. The work shown
The plastic poly mallets (top) offer
hammering metal that is supported
here is a fine-tuning operation, in the
resilient, shaped impacting surfaces
by a dolly, there is the critically
final stages of forming and flattening
that are great for forming shapes in
important distinction between on-
a surface.
metal without marring it.
dolly and off-dolly techniques. Work
on-dolly means that the dolly directly
result is to stretch that metal. Some-
have a feel and balance that makes
supports the metal that you are ham-
times this might be your object, or
them natural and comfortable to
mering and is placed exactly under
part of it, but sometimes it produces
swing. They are best swung with the
and in contact with the area that is
the unwanted result of stretching.
arm, from the elbow, with a slight
being hammered. This means that
Hammering off-dolly is much
flexing or unwinding of the wrist. The
you are hitting the metal between the
more common, and usually more
motion against the metal for most
hammer and the dolly. The inevitable
useful. In this technique, the dolly is
procedures should be a slapping
action that allows rebound, some-
times with a little bit of sliding thrown
in. This is not like driving nails.
Hammers should be held some-
what loosely, and with a limber wrist
behind them, to allow them to
rebound. You should pay attention
to that rebound because it contains
information about what is happen-
ing to the metal that you are ham-
mering. The sound that a hammer
makes also communicates informa-
tion about what its impacts are
doing to the metal. Most beginners,
and a few professionals, tend to hit
too hard with body hammers,
expecting one or a few master blows
to move the metal. In most situa-
tions, it is far preferable to use sev-
Dollies like these offer many useful surfaces for backing up hammer work. The
eral lighter blows. Good metal
three on the left are for working very small areas. The two larger dollies, with
workers develop distinctive rhythms
handles, can be mounted in vises and used in fabricating. The front dolly is
and timbres to their hammer blows.
rubber clad, and provides a somewhat resilient surface.
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AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
FOR M I NG, F IT TI NG AN D S MO OTH I NG
This photo shows hammering on-
dolly, but in this case the dolly is
rubber clad. This allows for fine
shaping, without much danger of
stretching the metal. Hammering on-
Shot bags come in many sizes and shapes, and can be filled with many
dolly with an iron dolly can cause
materials. The large, square bag (center) contains lead shot, and is useful for
excessive stretching, even if you are
forming fairly large items. The smaller bags (right) are hand held, for backing
careful to control this tendency.
up stationary items. The round bag (left) works both ways.
not held directly under the metal
rebound action. Various specialty
Bending, Beading and Prying
that is hammered, but offset from it.
dollies are available in many differ-
An example would be holding a
ent shapes and, in some cases, are
The fastest way to move a lot of
dolly under one or the other side of
clad in relatively soft materials, like
sheetmetal in a broad area is with
a ridge that is being hammered
rubber, to give them resilience, or
devices that bend and bead it. Bend-
down. The result is to level the ridge
dampening.
ing and beading apply more to fabri-
to the panel. There may be some
Shot and sand bags are very use-
cation than to repair. Prying, another
unwanted upsetting of the metal
ful for hammer forming three-
form of mechanical bending, is used
that is hammered this way but this
dimensional shapes. These bags can
mostly in repair work. The mainstays
can be corrected easily, later.
be filled with steel or lead shot, as
of equipment for bending body
Hammering
off-dolly
makes
well as sand or other materials. They
metal are brakes and slip rolls. Brakes
good use of the rebounding action of
are used to back up metal in a some-
are used to make straight-line bends,
the dolly, after it is impacted by the
what yielding manner. As you ham-
in sheet stock, to very precise angles.
metal that is being struck against it
mer metal on a shot bag, it dishes
They also can be used to radius flat
with a hammer. After the hammer
out. This provides relatively smooth
material by applying numerous, suc-
blow is struck, the dolly rebounds
forming and controlled stretching in
cessive, small bends to it. Finger
against the metal and acts to push it
the same operation. Shaped plastic
brakes, or box and pan brakes, are
out, toward the hammering force.
mallets, used with shot-bag backing,
useful for making bends in local
For this to work, the dolly must be
is a particularly effective hand-form-
areas, with standing metal on one or
pressed against the back of what you
ing combination.
both sides of those bends. Slip rolls
are hammering. You can easily imag-
Every autobody practitioner has
are used to impart permanent curva-
ine that driving a configuration like
some favorite backing surface for ham-
ture in one plane to panel materials.
a ridge down at its center, while
mering metal. These can range from
Bead rollers are specialty tools that
holding a dolly, alternately, under
anvils to blocks of various woods, and
are capable of rolling shallow beads
each side of the ridge, tends to level
even plastic materials. One of my
or other shapes into flat or slightly
the panel, and remove the ridge. As
favorite b
ackup surfaces is between
curved sheetmetal.
the ridge goes down, the metal bor-
one and three thicknesses (layers) of
Picks and pries are used locally to
dering it is kept level by the dolly’s
heavy, corrugated cardboard.
move metal, particularly in poor
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
49
CHAPTE R 5
This 16-foot sheetmetal brake is beyond the needs of most situations. It can be
Hand-operated bead rollers, like this
used for making bends in small items, too, and operates with an ease and
one, form beads and ribs into sheet-
precision that are wonderful. The counter balances make it very easy to control.
metal. Numerous forming and folding
dies are available for bead rollers.
Some of the more interesting
combinations use a soft top die and a
hard bottom one.
amount of force and frequency of its
application. This realization led to
some pretty violent devices for form-
ing metal. The most famous of the
early versions of these were the Pet-
tingell and Yoder power hammers.
These were huge, noisy devices that
used
a
wide
variety
of
shaping/stretching dies to greatly
speed the process of custom forming
metal.
Over the years, power hammers
evolved into much more compact,
quiet, and effective machines. Fore-
most in the modern crop of such
devices is the Pullmax, a machine
This finger or box-and-pan brake provides for bending around three-
used widely in prototype and
dimensional features of metal. It is shown here making a bend that would be
advanced metal restoration shops.
impossible with a flat brake.
In contrast to the earliest power
hammers, modern machines, like
access areas, where hammers and
Power Forming
the Pullmax, are as often used with
dollies cannot reach it.
the likes of Eckold shrinking dies and
All of the tools that are used for
Eventually someone realized that
Steck shrinking/shaping dies. These
bending, beading, and prying repre-
the action of striking metal with a
are general-purpose heads that can
sent non-impact methods of moving
hammer on a dolly could be mecha-
form and/or shrink metal very
and modifying metal.
nized, thereby greatly increasing the
locally and with no fuss. They are
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AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
FOR M I NG, F IT TI NG AN D S MO OTH I NG
relatively quiet and easy to use. The
tricky part of the proposition is to
know when, where, for how long, and
at what pressure settings to use them.
Before you add a Pullmax or other
power hammer to your want list, you
should know that these are very expen-
sive machines that are in the province
of professional, not amateur, use.
Pulling Approaches to
Moving Metal
So far, most of our attention has
been directed toward hitting metal
down with a hammer, or using a
dolly to hit or rebound it out. There
are also times when it is desirable to
pull metal. These situations are some-
times encountered in repair work. In
Pries and their close cousins, spoons, are used in many operations. The more
the most elaborate processes, pulling
robust items shown here, spoons, do prying duty or provide hammering backups.
plates are soldered, brazed, or welded
The lighter items are used only for prying. The homemade edge bender (top) is
to areas that require massive pulling
an item I fabricated from an old car spring.
force to return them to something
close to their original positions. Then
mechanical or hydraulic force is used
to pull them out by the plates. This is
very heavy duty repair work that
requires considerable equipment.
Smaller scale pulling is commonly
performed to remove dents, where
most of the displaced metal is locked
out of position by a very small area of
metal, and where access issues prevent
using impact tools to push out that
small area. Manual and mechanically
activated suction cups can be used for
very light duty pulling. Some shops
employ the barbaric practice of using
a slide-hammer to push or puncture
(or shoot) a hardened screw through
an area of a panel that is to be pulled.
Then, the screw is tightened into the
metal by turning it, and the slide-
Slip rolls, like this hand-operated machine, provide for uniformly bending
hammer is operated in the other direc-
metal in one plane. They impart predictable and continuous curves to sheet-
tion to pull the metal out by the screw.
metal. Slip rolls can also be set to put several different curvatures in the same
Avoid this rough approach.
panel, and to flatten distorted metal.
A more refined version of this
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51
CHAPTE R 5
practice is to use a stud welder to
weld a steel stud to a depressed area
of a panel, and then to use a slide-
hammer with a special clamp, that
holds the stud’s head, to pull the
metal out. When this operation is
finished, the stud can be ground
level to the panel.
Smoothing, Stretching,
Shrinking and Forming
Operations
Two of the simplest machines
made for metal working, the English
wheel and the planishing hammer,
are extremely useful for basic fabricat-
ing jobs. These exist in both relatively
inexpensive and high-end versions.
English wheels were among the
earliest applications of machines to
Stud welding involves using a specialized spot welder to resistance weld the
head of a stud to part of a panel, for the purpose of pulling its metal out. The
welding operation is very fast.
Once the stud is welded to the panel, a
specialized slide hammer grips its
shank. The stud is then slide hammered
This stud-welder attachment is great for pulling up small dings. The tool’s copper
away from the panel, pulling out the low
tip is resistance welded to the ding’s center, and then pried away from the panel
metal. The stud is then twisted or cut
with the tool’s levers. When the area is level, the tool is twisted slightly to break the
off, and the area is ground flat.
weld, and removed.
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wheeled metal. Stroking the metal
through the wheels at
different angles
makes it possible to form almost any
curved or dished shape. It takes con-
siderable practice to know where, with
which wheel combinations, with what
pressures, and for how many strokes to
use an English wheel. When you begin
to learn how to determine and com-
bine these variables, it is amazing what
you can accomplish with this simple
device. Wheeling is often performed
after some kind of impact procedure,
like hammering metal into a shot bag,
has been used to rough out a shape in
it. In these cases, wheeling can fine
tune the format of the metal, and
These old fender-smoothing tools amount to portable English wheels.
smooth out the results of the impacts
Although they date from the days of the Model T Ford, they are still useful in
used to form it before it is wheeled.
some situations. They are intended more to smooth than to stretch metal.
Unlike the power hammering
metal forming. While these devices
are only powered by human muscles,
knowledge, and imagination, they
are almost always larger items than
can be hand held, and are incredibly
useful for stretching, forming, and
smoothing metal for fabrications.
The basic device is a C-clamp-
shaped unit with two opposing
wheels that can be incrementally
tensioned against each other. The
wheels usually differ in diameter,
while the tension between them is
adjustable. The top wheel is gener-
ally flat, and much larger than the
bottom wheel. The bottom wheel
usually has varying degrees of lateral
curvature, and is almost always avail-
able in different contours.
The principle of the English wheel
is that as metal is pushed and pulled
between
the
tensioned
wheels,
the pressure stretches and forms it. The
curvature—and thus the contact patch
area and resulting pressure—of the
This imaginative wheel combination, mounted on an English wheel, uses a
shaped wheel helps to determine creasing lower wheel and a soft upper wheel, literally a caster wheel. The
the contour that is worked into the
result is to allow forming without excessive stretching.
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CHAPTE R 5
English wheels
devices mentioned earlier in this
come in many
chapter, English wheels vary from
