with which large work is required has led to the construction of
machines of an entirely different type in which there is no
designed limit of capacity. With these machines the limit to
the size of parts is no longer set by the character of the machine-
shop equipment but by the facilities of the railroad companies
for transporting the pieces, the limiting dimensions being
reached with the largest pieces that will pass through railroad
tunnels and bridges.
This system of machine tools, known as floor-plate tools, is
due to John Riddell, mechanical superintendent of the Schenec-
tady works of the General Electric Company, from which
works the system has spread to others doing large work.
The starting point of the system is the provision of a heavy
cast-iron floor plate made in sections, usually ten feet square,
and fitted with T slots by which both work and tools are bolted
down. Large floor areas are fitted with these plates, a section
of such a floor at the General Electric Company's Schenectady
works being shown in Fig. 172. The machine tools themselves
are of considerable variety, several being shown in Figs. 173
-176, from which it will be apparent that it is the individual
191
192
METHODS OF MACHINE SHOP WORK
FIG. 172. Modern floor plate.
FIG. 173. Portable floor plate drilling machine.
FLOOR-PLATE WORK
193
oj
E
fcO
3
I
13
194
METHODS OF MACHINE SHOP WORK
electric motor drive that has made the system feasible. Each
machine is provided with its own motor, convenient plugs being
provided for connecting at any convenient point. In each
case also the machine is provided with a suitable lifting bale
by which the overhead crane may transport it from place to
place.
FIG 176. Portable floor plate milling machine.
EXAMPLES OF FLOOR-PLATE TOOLS
Fig. 174 shows two portable Newton slotting machines at
work planing the feed of a motor frame. Fig. 175 shows a hori-
zontaf spindle Newton drilling machine mounted on an adjust-
FLOOR-PLATE WORK
195
able base and Fig. 173 a drilling machine of somewhat different
pattern, though by the same maker, engaged on a much larger
piece of work. In both cases the piece of work is mounted on a
central turn table. This last machine is also provided with a
vertical feed to the spindle head and Fig. 176 shows it at work
milling the dove-tail slots in an armature spider. The floor-
plate system as applied to heavy milling operations is shown in
FIG. 177. Section and half section of floor plate boring mill.
Figs. 240-242 and as applied to the cutting of large gears in
Fig. 270.
THE FLOOR-PLATE BORING MILL
One of the applications of this system is to the floor-plate
boring mill. The boring mill, like all machine tools other
than floor-plate tools, is limited in the capacity of the work which
it will take in, whereas the floor-plate boring mill, like other
196
METHODS OF MACHINE SHOP WORK
floor-plate tools, has no such limitation. The floor-plate boring
mill consists of a revolving table sunk in the regular floor plate
which surrounds it, the work and the machine tools being
mounted upon the revolving and the stationary plates in various
ways and in accordance with the requirements of the piece of
work in hand.
A section and half section of such a floor-plate mill at the works
of the Crocker- Wheeler Company is shown in Fig. 177. The
revolving table is shown at a, the center piece b being stationary
FIG. 178. The tool revolves while the work stands still.
Work of the floor-plate boring mill.
and serving as a bearing for the revolving table. A supple-
mentary, non-revolving, removable piece c is provided, properly
fitted at its center so that it may be quickly dropped into place
concentrically with the other parts. This supplementary piece
is only occasionally used but it adds materially to the flexibility
of the machine. 1
In use, the work is sometimes bolted to the surrounding floor
plate, the tool being mounted upon and turning with the re-
1 The heavy lines of the upper view show oil supply and drain pipes.
FLOOR-PLATE WORK
FIG. 179. The work revolves while the tool stands still.
I
L
FIG. 1 80. The work revolves while the tool stands still.
Work of the floor-plate boring mill.
198 METHODS OF MACHINE SHOP WORK
volving table, while in other cases the reverse arrangement is
used, the arrangement being determined by the size of the work.
Fig. 178 shows a generator ring frame mounted upon the sur-
rounding plate and the tool mounted upon the revolving plate,
other tools performing additional operations simultaneously.
Fig. 179 shows the reverse arrangement, the work being here
mounted on the revolving table while the tool support is
mounted on the surrounding floor plate. For still smaller work
as in Fig. 180, the tool is mounted upon the inner supplemen-
tary plate, which does not revolve, while the ring frame is
mounted upon the revolving table and, obviously, if re-
quired, the reverse arrangement may be used, the work being
mounted upon the supplementary plate and the tool upon the
revolving table.
CHAPTER X
DRILLING
Types of drilling machines Jigs and their uses Gang, multiple-
spindle and station drilling machines The laying-out machine for the
accurate spacing of holes The base line system of drawings Other
methods of spacing holes The master plate.
TYPES OF DRILLING MACHINES
The drilling machine is made in a great variety of forms, of
which three by the Cincinnati Bickford Tool Company are
shown in Figs. 181-183. The most common form, called the
upright drilling machine, with modern and unusual features, is
shown in Fig. 181. With the two that follow, it is fitted with
the popular constant -speed pulley drive. 1 By means of the
two bevel gears on the upper end of the spindle and their con-
nections, the spindle may be revolved in either direction and
with the back gears and the convenient lever for manipulating
them the speed may be quickly changed. Thus equipped the
machine may be used for tapping as well as drilling. The tap
having been driven through the work, movement of the front
lever depending from the driving head reverses the tap, when
movement of the rear lever accelerates the speed of withdrawal.
A depth gage for the depth of drilling and an automatic trip
whereby the feed is automatically stopped when the desired
depth has been reached are also provided.
To accommodate work in which holes must be drilled at a
considerable distance from their sides the radial drill, Figs.
182 and 183, has large application. In most cases these
machines are made as shown in Fig. 182, the drill spindle being
always vertical. Such machines are called plain radials. In
1 To the best of the author's knowledge, the first machine tool of any kind to
be thus driven was a Bickford drilling machine exhibited at the Pan-American
Exposition of 1900.
199
200
METHODS OF MACHINE SHOP WORK
other cases as in Fig. 183 the arm is so made as to swivel about
a horizontal line and the drill spindle about its vertical center
line, whereby the spindle may be made to perform its function
FIG. 181. Upright drilling and tapping machine.
at any angle with the horizontal and vertical planes. Such
machines are called universal radials. Sometimes one of these
adjustments is omitted and the machine becomes a semi-
DRILLING
201
FIGS. 182 and 183. Plain and universal radial drilling machines.
202
METHODS OF MACHINE SHOP WORK
universal radial. The convenience of the universal and semi-
universal machines adapts them to the performing of otherwise
difficult operations, but the necessary joint at the base of the
arm precisely the point where stiffness is most needed robs
them of stiffness and, except as regards this convenience of
adjustment, which is only occasionally required, the plain
radial is much to be preferred.
DRILLING JIGS
Drilling in connection with manufacturing operations is
always done in connection with drilling jigs which take a great
FIG. 184. Various forms of drilling jigs.
variety of forms, a few of which are shown in Fig. 184. The
object of a drill jig is to guide the tool, the laying-out of the
holes being done once for all on the jig, uniformity of spacing
DRILLING
203
in the work being thus assured. To insure permanence of the
locations the holes are bushed with hardened steel bushes.
Eventually even hardened bushes wear, but it is then a simple
matter to remove the old and insert new bushes, the result
being to restore the jigs to their original accuracy.
This word jig is properly applied to appliances which guide
cutting tools. Numerous other appliances used in connection
FIG. 185. Large boring bar jig.
with other operations which locate the work, rather than guide
the tool, are frequently called jigs but are more properly
fixtures.
Jigs for large work are frequently seen, such an one from the
Cincinnati Planer Company being shown in Fig. 185, which
illustrates a jig for the bearings of the various shafts which
extend through a planer bed. These bearings it serves to locate
in proper position with respect to one another and also with
respect to the V's of the planer. The jig has locating V's
204 METHODS OF MACHINE SHOP WORK
which enter the V's of the planer bed. The tool guided by the
jig is a boring bar which is guided at both ends by bushes in
the jig body, the drive being from a radial drilling machine
through an adjustable knuckle joint.
GANG AND STATION DRILLING MACHINES
Drilling machines are frequently arranged in gangs, of which
an example by the W. F. and John Barnes Company is shown
FIG. 1 86. Gang drilling machine.
in Fig. 1 86. With a piece of work in position the operator
has but to trip a lever when the drill drops to the work, feeds
through it and, when the hole is finished, automatically flies
back to the starting point. The spindles are fitted in succession
with various drills and reamers, the work being shifted from
spindle to spindle and the four tools operating simultaneously on
as many pieces. Arranged in this manner the equipment be-
comes essentially a station machine in which the shifting from
station to station is by hand.
DRILLING 205
An automatic station drilling machine by the Windsor
Machine Company is shown in Fig. 187. The work is carried
on a turn table fitted with as many chucks as there are drilling
spindles plus one, an extra station being required for loading
and unloading the chucks. The feed is effected by the vertical
movement of the turn table which revolves one step after the
completion of each drilling operation. Each piece of work is
finished as it passes the last operative station from which the
next indexing movement carries it to the idle or loading station
where the finished piece is removed and a new one is substituted,
with a drilling operation in progress. The spindles are driven
by universally adjustable telescopic connections permitting
lateral adjustment of the cutting tool to any point on the face
of the work and change gears are provided by which the speeds of
the different spindles may be independently adjusted. Other
operations than drilling, such as reaming, counterboring, etc.,
suitable for revolving tools may be carried on. 1
MULTIPLE-SPINDLE DRILLING MACHINES
A comparatively recent development of the drilling machine is
the multiple-spindle machine, if which an example, by the
Baush Machine Tool Company, is shown in Fig. 188. The
drills are driven from the central spindle by gearing and uni-
versal telescopic joints and are adjustable in number and to
cover any layout within the limits of the machine.
Small multiple-spindle drill heads are frequently made for
attachment to otherwise plain machines such attachment
being frequently homemade for the work in hand. Two such
cases from the works of the General Electric Company are shown
in Fig. 189 together with the jigs which go with them. The
various spindles are driven by suitable gears, all connected to a
central gear attached to the main spindle at the center.
Other cases of multiple-spindle drill heads by the Langelier
Manufacturing Company are shown in Figs. 190-192. Each
of these is designed for a special piece of work and different
heads are made to interchange on the same drilling machine.
1 The reader should compare this illustration with Fig. 159 showing a station
machine in which the work revolves.
206
METHODS OF MACHINE SHOP WORK
c
P
DRILLING
207
The driving of the spindles is by the mechanism shown in Fig.
193. Each spindle carries above its bearing an offset crank,
the spindles being driven in common by a crank plate
FIG. 189. Multiple spindle drill heads.
mounted eccentrically in the main spindle. This construction
permits the spindles to be grouped together more closely than
any other, the limiting center distance being two diameters of
the drill.
208
METHODS OF MACHINE SHOP WORK
1.1
DRILLING
209
FIG. 193. Method of driving multiple spindle drill heads.
14
FIG. 194. An example of highly organized multiple spindle drilling.
210 METHODS OF MACHINE SHOP WORK
A highly organized piece of multiple-spindle drilling from
the works of the Westinghouse Electric and Manufacturing
Company is shown in Fig. 194. The work in progress is the
drilling of one side of a shell of an electric railway motor. The
scheme is to provide two jigs, one of which is loaded with work
while the other is under the drilling machine in action, and then,
in addition to this, to provide means for the quick interchange
of the two jigs. A suitable track and turntable will be seen, a
short piece of track, not seen, extending underneath the drilling
machine and at right angles to the track shown. The jigs are
fitted with wheels suitably flanged for the track. From a pile
of undrilled castings in the foreground the operator loads the
jig, provisions for doing which quickly are provided as shown.
Meanwhile a preceding casting has been drilled under the
machine. When finished it is run out on the turntable which is
turned through ninety degrees and the jig and its work are
run off to the rear where the jig is unloaded. The previously
loaded jig is then run on the turntable and under the machine,
when the other jig is run back to the loading position and loaded,
this sequence of operations going on indefinitely.
LAYING OUT MACHINES FOR SPACING HOLES
The accurate laying out of holes in jigs is a subject on which a
book could be written. It is, perhaps, the master operation of
the tool room and a great many methods of doing it have been
devised.
A superior method of doing this is by the use of a special
machine, for this purpose only, from the works of the Burrough's
Adding Machine Company, shown in Fig. 195. The machine is
by the Sigourney Tool Company from designs by the Burrough's
Company. The work table is arranged similarly to that of a
knee-type milling machine with the addition that it has fitted
to the work table, in such positions as to read in two directions
at right angles from one another, two finely graduated scales
which are provided with verniers. With this construction the
adjustment of the table may be made with great accuracy and
convenience, the convenience being increased by the fact that
both scales and verniers are adjustable endwise in order that the
DRILLING
211
212 METHODS OF MACHINE SHOP WORK
work may be begun with the first reading at the zero or, more
frequently, at an even inch of the scale. To prevent the side-
wise crawling tendency of the drill on the surface of the work,
it is guided by a bush inserted in an arm which projects from the
machine frame and since, because of the clearance with which
they are provided, twist drills cannot be made to fit jig holes
with precision, the hole, after being drilled, is reamed with a
rose reamer having a ground shank which accurately fits a
second bush in the same arm. The machine is fitted with a
complete assortment of bushes and reamers which are kept in
the cabinet below it.
The largest and finest example of this method of attacking
the jig-making problem with which the author is acquainted is
shown in Figs. 196-198, from the (British) firm Alfred Herbert,
Limited. The general principle of the machine does not differ
from the one just shown, although it will be seen to have much
greater capacity, the longitudinal traverse being sixty and the
transverse traverse thirty inches. The method of measuring
the distances between holes is, however, entirely different and
capable of much greater accuracy, being based on the use of
end measure rods, micrometer screws and gravity drop pieces,
these last being similar to the drop piece described in connec-
tion with the Pratt and Whitney measuring machine. These
features are used for the fine adjustment only. While the
traverse screws are not depended upon for final settings, they
are fitted with graduated dials for the coarse adjustments and,
to save the counting of their revolutions, graduated scales are
provided for both longitudinal and transverse movements.
Referring to Fig. 197, the pilot wheel by which the transverse
adjusting screw is manipulated is plainly seen. Beyond it,
near the base, is its graduated dial, beyond which, on the bed, is
the scale. In the foreground is the micrometer dial and in
front of it the gravity drop piece, while beyond it on the base
is the end-measure rod. The corresponding parts for the
longitudinal adjustment are shown in Fig. 198. As the moving
parts are heavy a more sensitive adjustment than that of the
pilot wheels is necessary, the provision for this being most
clearly shown in Fig. 197. It consists of a lever which, while
DRILLING
213
FIGS. 197 and 198. Details of large tool room laying out machine.
214 METHODS OF MACHINE SHOP WORK
usually free from, may be clamped to the traverse screw. The
lever is provided with an adjusting screw at its end which bears
on a fixed abutment. With the lever clamped to the main
screw, the adjusting screw will obviously give very fine
adjustments.
The table feed and adjusting screws of high-class milling
machines are made to a high degree of precision and are fitted
with micrometer dials whereby readings to thousandths are
obtained. With the work clamped to the work table and a
boring tool placed in the spindle, the lengthwise, transverse and
elevating screws provide means for measuring the spaces be-
tween holes in a manner analogous to those used with these
laying-out machines. This plan is often used but is not to be
recommended unless the milling machine is new. Accurate
screws are provided in these machines because customers
expect them and not because it is a suitable place for such
screws, for it is not. Their use as feed screws under the pressure
due to the cut leads to wear which is greatest where the screws
are most used, that is near their centers of length. Conse-
quently, whatever their accuracy when new they do not long
retain it.
The appropriate construction would embody the division of
functions which appears in these laying-out machines, in
both of which the moving of the parts and the measurement of
the movements are entirely distinct and hence wear of the screws
has no effect on the accuracy of the readings. The Herbert
machine is unnecessarily refined for commercial milling ma-
chines but there seems to be no reason why the Burroughs con-
struction is not applicable to such machines.
BASE LINE DRAWINGS
Drawings for work to be made on machines of this type are
laid out on the base line plan. Were the dimensions between
holes given as is common on construction drawings, the practice
would necessitate a large amount of addition and subtraction
of fractional dimensions in order to obtain the readings of the
scales, a process which would not only consume time but would
be productive of errors. These objections are overcome by the
DRILLING
215
base line drawings in which the locations of all the holes are
laid out as coordinates from base lines. An example of this
kind of drawing is shown in Fig. 199. The locations of the
holes are always the true readings of the scales so far as the
fractions are concerned, although the whole inches frequently
differ in accordance with the location of the zeros of the scales.
In some cases the base lines are external to the piece of work
while in others, as in the present case, the base lines pass through
K 0.620 s - *
\*- 0.544 " - -;->
I K- 0525 -*
I \\f- 0.5225^ - - -f
(<- -Q38/3 ^
Tirz _i i w u
4- -F- e '-e- .
iQli^ili^^
a ' i ! 1 1 *-**-*=*- -= - -=
FIG. 199. Base line drawing for use with laying out machines.
the center of one of the principal holes. This hole being made
first and the scale and vernier adjusted to read zero or an even
inch, the locating of the other holes becomes a simple matter.
OTHER METHODS OF SPACING HOLES
These machines provide the most obvious and the quickest
method of locating holes with accuracy and their cost would be
justified in a large number of shops. Nevertheless they are
216
METHODS OF MACHINE SHOP WORK
seldom found and other methods, of which many have been
developed by the tool makers, must be resorted to. An ex-
tremely accurate and satisfactory method has already been
shown in connection with the Johansson gages, Fig. 106, and the
same plan is obviously applicable and is frequently used with
plug and other forms of gages as indicated in Fig. 200, in which
the discs are of such diameters as to shift the piece of work by
such amounts as will bring the centers of the desired holes in
3
GOO
C ) tJ
1
000
3
C) C)
FIG. 200. Gage method of accurately spacing holes.
line with the lathe spindle. In these cases, as, indeed, in most
others, the holes are finished with a single pointed lathe boring
tool which assures perfect alignment of the holes with the lathe
spindle. By this plan, the work being swung in the lathe,
the size of the pieces which can be treated is limited by the
capacity of the lathe.
A method which, for the highest class of work, has, perhaps,
found larger use than any other, is the New England button
DRILLING
217
method which, while slow, is capable of results of the highest
degree of accuracy. This method is shown in Figs. 201-203.
The process involves the preliminary positioning of a series
of buttons at the exact locations where the jig holes are required.
The buttons are small cylinders of hardened steel of exactly
the same diameter with holes through them endwise and with
them go small cap screws of a diameter somewhat less than
that of the holes through the buttons.
The jig having been planed, the tool maker lays out the holes
as accurately as may be with scale and dividers and drills and
taps holes for the button holding cap screws. The buttons are
then lightly secured in their approxmate positions as shown in
3
'Jig
Cen ter of Spindle
^-Button
FIG. 203.
Ite
Jig-'
FIG. 202.
The button method of spacing holes.
Fig. 201 and, using a parallel strip and micrometer as in Fig. 202,
they are adjusted to the exact position desired. The jig is
then strapped to a lathe face plate as in Fig. 203 and carefully
positioned until the tool maker's indicator stands still as the
lathe revolves, showing the button to be exactly in line with the
lathe spindle. The button is then removed and the hole is
enlarged to the required size by a boring tool held in the tool
post. The jig is then shifted on the face plate to bring the
other buttons successively in line with the spindle when, the
holes being bored, they are obviously accurately spaced.
218
METHODS OF MACHINE SHOP WORK
As with the gage method the pieces which can be handled in
this way are limited in size by the capacity of the lathe and in
such cases the button method may be applied to the milling
machine as indicated in Fig. 204. The indicator is here mounted
in the spindle of the milling machine and the jig plate is
FIG. 204. Use of the button method on milling machines.
adjusted by means of the milling machine table screws until
the indicator index stands still when the spindle is revolved.
This button is then removed, a boring tool is substituted for
the indicator and the hole is bored the process being repeated
in succession for the remaining buttons.
Twist drills cannot be depended upon for making the holes,
DRILLING
219