New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1900-09-30
HUGE GRANITE COLUMNS.
SHAPED AND POLISHED IN A LATHE
TO ADORN THE EPISCOPAL CATHEDRAL IN THIS
CITY-THE BIGGEST MACHINE OF ITS
KIND IN THE WORLD
KIND IN THE WORLD.

KIND IN THE WORLD.
For the Cathedral of St John the Divine, IN
this city, thirty-twO magnificent granite col
uInns are to be supplied, each as high as a four
story house, and TO shape them a remarkable
piece of machinery has recently been constructed
in Philadelphia and sent to the quarries Of the
Bodwell Granite Company in Vinalhaven. Me-
1t is nothing less than a turning lathe Of IN
paralleled strength and proportions.
a good Illustration of the objects and opera
ton of a lathe is found in shop where wooden
balusters are manufactured A stick Of wood,
three or four inches square and two or three
feet long, is adjusted in a horizontal position.
with its ends firmly held by metal disks. which
are intended to revolve rapidly The stick being
thus set in rotation, workman applies TO it the
edge of chisel, or other cutting tool which
rests on a fixed support but may be shifted
from one end of the stick TO the other. The
result of this treatment is to make the stick
perfectly round in a very short time. Its diam
eter at different points may be varied if this
is desirable. so that in one place there is
graceful bulge and in another a slender taper.
Lathes also built for working metal. and
the cutter is usually shifted automatically by a
screw motion, so that the lack of uniformity
which results from hand work is eliminated and
absolute adherence to a model insured.
The same method is now employed in shaping
long blocks of stone into columns like those in
front of the New-York Life Building in Broad
way The stone is suspended horizontally be-
tween the head stock" and tail stock" both
of which can rotate. As in other lathes. the
power which causes the stone to revolve is ap-
piled to the head stock By arranging suitable
cutting tools on the side the superfluous material
is Clipped off by degrees and the column is re-
duced to the desired dimensions as surely.
though. of course, not so rapidly, as wooden
baluster.
The finished columns of the Episcopal Cathe-
dral are TO be a feet long, and have diameter
of 6 feet When finished each will weigh 100 tons.
But to begin with block is quarried out that
is 60 feet long, measures S1a by . feet in cross
section, and weighs about 80 tons. This bur
den must be sustained by the two rotating ends
of the marvellous machine recently sent to
Vinalhaven. Before the lathe is put in operation
it is intended that little of each rectangular
edge shall be taken off from the block by hand.
Eight cutting tools will he adjusted close to
each other, one going little deeper than its
predecessor Each is designed 10 cut off three
inches OF stone so that together they would
be capable of making cut twenty-four inches
in depth. BY a suitable mechanism these cut
tiers are slowly shifted from end of the
lathe to the other, so as to traverse the whole
a manner that they cannot make the diameter
less than six feet.
When column has thus been brought down
to the proper size it still has rather rough
surface. The stone must now be polished This
second operation is conducted with the lathe
also but the rotation is effected at a somewhat
higher rate of speed. There are two polishing
processes. The first. rough polishing, is
done with a cup shaped device that mas lot
of hardened steel shot in contact with the NOV
ing surface. In the final operation sand and
emery are employed. \ period of about six
weeks is required for each column. 1t viii take
nearly four years. therefore, TO get out the
whole thirty-twO columns.
This machine is So feet long and weighs $50
tons. 1t is much larger than any other stone
cutting lathe ever before constructed. II IS
driven by a fifty horsepower engine When en-
gagged in cutting its speed is one and three
quarters revolutions minute. and three when
used for polishing. The change of speed is eff
fected by gearing The work of constructing
the lathe was begun in December last, and it
was delivered to the BodweH Granite Company
in MAY. But it was not put into operation until
a few weeks ago