Western news and the Libby times. [volume] (Libby, Mont.) 1920-1933, 1929-01-10
GREAT ACCURACY NECESSARY
IN MANUFACTURING FORDS

| A million axle shafts, each one ex-
actly like the other 999,999 within
one thousandth of an inch--four mil
lion pistons fitting four million cyl
inders with a degree of exactness
that all but staggers the imagination
many more millions of drilled and
threaded holes, all placed with an
accuracy of location that is incom-
prehensible to any but the mechanic
ally or automatically minded-and
all these factors, combined with other
millions of parts manufactured in
widely separated units of gigantic
| plant, meeting on an assembly line
to fashion a million automobiles. This
is the miracle that is modern mass
! production, the miracle that was con-
jured up by Henry Ford when he
started his first automobile assemble
line.
The story of how it is possible to
make a million--or ten million, or
twenty million, for that matter-of
any machine part, each one identical
with all it's fellows, is a story of
measurements. Just as that story Of
measurements explains the ability of
the Ford Motor Company to produce
fifteen million Model T. automobiles,
it also explains Mr.. Ford's ability to
produce the Model A in the same
plants and by the same methods that
made possible the pioneer Ford cars,
yet at limits that are from one quar-
ter to one half what they were on
the Model T.
Today, in the Detroit plants, me-
chanics who have never looked
through the eye-piece of a micro
scope are measuring within limits too
fine for any unaided eye to see. Mod
ell A. ~parts machined to within one
ten-thousandth part Of an inch ac-
curacy are all in tire days work. Back
of this precision are something like
million cages that must be kept
in correct adjustment at all times
and many thousands of these cages
are in constant use throughout the
Ford plants. There is no time for
handefitting of inaccurate parts on
the assembly line. TEey must. either
fit the first time or they are valueless.
Therefore, the parts must leave the
various machines which fashion them.
with every specified dimension cor
rect. The result is that when put t67
gether, the car moves off the assem-
bly, line under its own power, com
pleted means of transportation re-
curing no special adjustments.
There are inspection and working
cages to measure outside and inside
diameters, lengths, widths, heights,
angles, pitch, diameter and lead Of
screw threads, which are in the hands
of Workman-t throughout each-day,
testing and checking each part as
it passes from machine to machine
through the plant. But these cages
will wear or get slightly out Of adj
| justment under constant use, there
fore, they must be constantly
watched. So behind them must be
master cages, Of greater accuracy,
for use as standards. These master
cages are accurate within a millionth
part of an inch!
/ Throughout the Ford plants in
| spectors are moving constantly, each
with special hardened, ground and
| Tapped rectangular steel blocks. These
gage blocks are in special sizes to
meet requirements Of the workman's
scrutiny, making it unnecessary for
inspectors to make up combinations
to measure different dimensions of
length. A set of 81 gage blocks, such
as is used in the. tool rooms, can
be combined to measure 10000 diff
ferent size lengths, from three-six-
teenths inch to over twelve inches,
and each Of the 10000 combination
cages represent variation of one
ten-thousandth part Of an inch.
On some operations where the linn
its are close, the cages are changed
every two to four hours to correct a
wear Of one ten-thousandth part of
an inch which occurs in that time.
Others are adjusted or changed at less
frequent intervals, as frequency of
use and amount Of wear dictates.
Valuable Lichens