METAL BODY REPAIR - OD1653 - LESSON 1/TASK 1
difficulties caused by the collision involves other skills and techniques
than are practiced by the collision expert, he cannot ignore them and must
provide for their correction.
(3) Each part of the damage occurred in a certain order. It is
necessary to correct it in the reverse order of the way in which it
occurred. Studying the damage permits you to reconstruct the sequence of
events which caused the damage, thereby providing the proper order in which
the damage should be corrected.
Roughing and Aligning.
(1) After analyzing the damage, the next step in body and fender repair
is metal bumping (roughing) which is the important unlocking and unrolling
operation. If this is done carelessly or hurriedly, new lines of strain
will probably be set up, stretching and bending the metal at such sharp
angles that a further rearrangement of the displaced fibers will be
(2) Before repairing fenders, scrape off any tar, gravel, or road dirt
underneath the damaged part. Any dirt left on the underside will cake on
the dolly block, so that hammering smooth will be impossible.
(3) The outside surface of the damaged fender or panel is then wiped
with a rag which has a small amount of thin motor oil soaked into it. This
removes dust and grit which would otherwise stick to the hammer face and
hinder the worker from securing a smooth surface. The light reflected from
the oiled surface shows the extent and depth of the various bumps.
(4) Since metal bumping and finishing are simply a matter of hammering,
it should be learned at the outset how to use the hammer and dolly. The
simple secret is to make every blow of the hammer strike the metal directly
above the dolly or spoon.
(5) A simple application of the use of a hammer and dolly block is shown
in figure 13 (on the following page). The downstroke of the hammer drives
the high spot down onto the face of the dolly block, smoothing the metal.
The dolly block absorbs the shock of the hammer blow and prevents the
damaged metal from being driven down too far.