The Red Cloud chief., 1889-03-15
ABOUT CIRCULAR SAWS.
How the Plates from which They Ar
Msao Are Treated asd Tempered.

How The Plates from which They Ars
Msds Are Treated asd Tempered.
Ordinary circular saws are Of all
sizes from elk inches TO six feet il
diameter. The plates from which they
are shaped come from steel mills il
circular form. almost round. il not
perfectly SO. The first thing Ia b
done is to see that each plate is made
. perfect circle. 4 hole is then cut in
the center. and the teeth are marked
around the rim. The plate 10 thea
taken to q machine on which the teeth
are to be cut. 1t is placed upon a pin
1t such q distance from the machine
that the edge comes beneath the die.
and the operation Of i~eeth-cuiting be-
gins. The steel is cut cold. each tooth
being made by n blow. All sizes and
descriptions Of dies are necessary, as
the style Of saw and saw-tee;h are
many. After the teeth have been cut
the next operation is tina; OF temper
ing. which is the most difficult aud i'm
pOrtant process in the making OF q
saw. Several saws arc placed in the
furnace At . time and allowed
to remain until they have reached
the proper temperature. q light
cherry red. when the plates must be
taken from the oven and plunged into
. vat Of whale oil. heated by pieces Of
red-hOt iron or steel. which are placed
in the vat one after another until its
contents are properly heated. As each
piece is dropped in. q brilliant, flame
leaps from the surface Of the oil, and
continues TO burn until extinguished
by stirring the liquid with . long iron
rod. The large glowing plates Are
then cautiously slid into the vat Leav.
ing the tempering department. the saw
goes back to the main shop % be ham,
mered and Strengthened ready for
grinding. This work is done by hand.
After the plate. which has been more
or less warped during the tempering
process. has been made perfectly
straight again. it is placed in the grind
ing machine. which il = carriage b.
tween two wheels which turn il. and at
the same time press its sides against .
rapidly revolving grindstOne. The car
riage 10 fixed In automatic bearings.
and Is moved back and forth At the will
Of the operator. 1t usually takes about
two hours to grind a large five-fOOt Cir
cular saw. though the time varies &c
cOrding TO the kind Of saw that is being
made. The next operation is that Of
polishing. which Is done with emery
wheels. To polish a large circular saw
the plate is secured 10 a large wheel or
dange, which turns. carrying the saw
with II. the wOrkmen meanwhile press
ing an emery ball attached to u handle)
against the side.
The saw must then be rounded"
that is. care must be taken To prevent
ono tooth projecting farther than the
others. For this purpose the saw is
placed in a bearing. and made 10 turn
slowly. 1t is then gradually brought
in contact with an emery wheel. the
latter turning very swiftly. until the
edge Of every tooth touches the wheel.
The saw is next sharpened and sub
mitted to further hamnering for the
purpose OF ''truing' and straighten-
ing. and is then cased ready for ship
ment.
One important part Of the saw
makers business is the renovation Of
old saws injured in fires. 1t is straight
ened up. tempered over again. and pro-
vided with n new Sc; Of teeth.
This article has dealt only with COM
circular saws. the teeth Of which
are not separate from the plate. Other
however. supplied with inserted
teeth OF various kinds. are made in
numbers. These are all patent
SAWS. and can be supplied with new
sets u false teeth as often rs necessary.
Mechanical News.