Please wait. Contacting image service... loading

Article text

Precision of Ford Engineering
To maintain absolute accuracy in the
manufacture of Ford cars the Ford
Company uses the famous Johansson
system of gauges, which are capable
of measuring exactly one-millionth of
an inch. These gauges satisfy the
ford demands for accuracy because
they permit a limit of one-tentn the
thickness of a sheet of onion-skin
paper in such parts as the V-8 piston
and connecting rods. At 172 opera
tions in machining and inspecting ol
parts for the Ford car there is a
tolerance ol five ten-thousandths ol
an inch, or half the thickness ol a
piece of onion-skin paper. A few
measurements are made to two-ten
thousandths ot an Inch to ensure in
the parts longer operating life.
A Johansson gauge is a rectangular
block made from nickel steel, the dis
tance between two of the faces being
accurate within the limits specified in
miilionths of an inch. So periectly
are the faces of these blocks finished
that two or more blocks can be
"wrung" together with a (listing
motion, after which they rill adhere
so firmly that it takes a considerable
pull—even allowing for atmospheric
pressure—to separate them. A set of
these gauges consists of 81 pieces, and
by using them separately or combined
more than 20,000 different sites can
be obtained.
$