Improvements in Machines for Drilling Gun Barrels and the like.
Year: 1891

page_text: Date of Application, 13th Feb., 1891-Accepted 16th May, 1891
COMPLETE SPECIFICATION.
Improvements in Machines for Drilling Gun Barrels and the like.
THE PRATT AND WHITNEY COMPANY of No. 1 Flower Street, Hartford in
the County of Hartford and State of Connecticut, United States of America,
Manufacturers, and CHARLES WILLIAM SPONSEE of same place, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to machines for drilling gun-barrels by means of a drill
automatically fed to its work, and having a forced supply of oil (or other lubricating
fluid) delivered through the drilling tool to the face of the bore.
In the drawings accompanying and forming a part of this Specification
Fig. 1 is a plan view and Fig. 2 a front elevation, of a barrel-drilling machine
embodying my invention.
Fig. 3 is a plan view, drawn on a larger scale, of that portion of the machine
which is at the left-hand in Figs. 1 and 2.
Fig. 4 is a front or side elevation of that part of the machine shown in
Fig. 3.
Figs. 5 and 6 are a plan and a front elevation, respectively, of the middle
portion of the machine, as will be seen by comparison with Figs. 1 and 2.
Fig. 7 is an elevation of the end of the machine at the left-hand in Figs. 1, 2, 3
and 4.
Fig. 8 is a vertical transverse section in a line at the right-hand of the parts
shown in Fig. 4; this view shows the head of the machine and the parts carried
thereby, as seen from the right-hand in Fig. 4.
Fig. 9 is a longitudinal vertical section through the head of the machine, this
being the portion shown in Figs. 3 and 4; this view shows more in detail the
construction of the driving-spindle.
Figs. 10 and 11 are cross sections in lines a a and b b, respectively, of Fig. 5.
Fig. 12 is a vertical longitudinal section of the parts shown in Figs. 5 and 6.
Fig. 13 is an end view, partially in section, of the barrel-rest.
Fig. 14 is a side view (partially broken away) of the oil-pump, the cap or
covering being removed.
Figs. 15 and 16 illustrate the construction of the improved drill used in the
machine.
Similar characters designate like parts in all the figures.
The main-frame or bed of the machine, which is designated by B, is supported on
legs, as 2 and 4, and is shaped and fitted to carry the several mechanisms and
operative details. The frame, 3, of the drilling-machine head, is fixed to said bed
by screws, 5, and is provided with the barrel-carrying spindle 10, which is furnished
with suitable spindle-driving means, and is also connected to actuate the drill-
feeding apparatus. The spindle 10 is journaled in the front-bearings 9, which is
carried by the upright 8 of said frame 3; in the middle bearing 7, which is carried
by the upright 6 of said frame; and, in the rear-bearing 14, formed in the frame.
The rear-bearing 14 has the usual cap 15, and the bearings 7 and 9 are held in
place by caps 11 and 13, respectively, secured by screws in a well-known manner.
Said rear-bearing is carried by the rearwardly-extending yoke-shaped part, 12, of
the frame 3, which also carries the thrust-screw, or step, 16, (provided with a
check-nut 17,) for taking the end-thrust of the spindle 10. For actuating said
spindle, it is provided with the loose pulley 18 and the driving pulley 20, the loose
pulley being fitted to turn freely on the said spindle between the outer bearing 14
and a friction-collar, 19, which is removably fixed to the spindle by means of the

page_text: set-screw 21. The driving pulley 20 is fitted to normally turn freely on the spindle
contiguous to said collar 19; the hub, 22, of said wheel being clamped between
said fixed collar and a sliding friction-collar, 24, that is furnished with a screw, 23,
whose point engages a slot, 25, formed in the spindle; this construction, shown best
in Fig. 9, permits the free longitudinal movement of said collar, while preventing
rotation thereof on the spindle. A spring, 26, is carried by the spindle between the
collar 24 and the adjusting-nut 27; which nut is screwed onto the threaded part, 29, of
the spindle 10, and is provided with a set-screw, 28, as a means for fixing the same in
place on said spindle. In practice, the spring 26 may be carried directly on the spindle;
but it is preferably carried as shown, by an extension of the nut itself, thereby providing
for a larger and more even-tensioned spring of a relatively short length. The spindle 10
is revolved by means of an ordinary belt, as D, running on the pulley 20, (Fig. 8,)
and through the pulley-clamping devices above described. By this means the
spindle is yieldingly driven, so that any unusual obstruction will cause the pulley
to slip, and thus avoid in a large degree the breakage of drills. A flange or
collar, 30, formed on the spindle 10, and a nut, 31, screwed onto said spindle and
fixed thereto by the set-screw 32, serve to hold the spindle in place longitudinally.
A suitable chuck, as 33, for holding the small end, or muzzle, of the barrel to be
drilled, is firmly screwed or otherwise fixed to the forward end of spindle 10; said
chuck, in the preferred form thereof herein shown, is split on one side for a portion
of its length, and has a clamp-screw, 34, for closing the same onto the small end
of the barrel C, as will be understood from Fig. 9. A worm, 35, (which may be
fixed to the spindle 10 by a pin, 36,) meshes with and drives the worm-gear 37,
which is fixed to the shaft or stud 38, that is journaled in bearings formed on the
head 3; said shaft lies at right-angles to the spindle 10 and carries fixed to its
forward end a worm, 39, which meshes with the worm-gear 40, that is fixed to one
end of an intermediate shaft, 41, journaled in suitable bearings, as 42 and 43, formed
on the main-bed of the machine. Said shaft 41 has removably fixed to the rear-
ward end thereof a gear, 44, which meshes with another and similar gear, 45,
similarly fixed to the end of the feed-screw 46. One end of said feed-screw is
journaled in a bearing, 47, formed in the left-hand end of the bed B, the opposite
end thereof being journaled in a similar bearing, 48, at the right-hand end of said
bed. By substituting differently-proportioned gears for the change-wheels 44
and 45, the relative speeds of the spindle 10 and the feed-screw 46 may be varied
as required.
For starting and stopping the machine, a shipper mechanism is provided for
shipping the belt from the loose pulley 18 onto the driving pulley 20 by hand, and
from the pulley 20 back onto the pulley 18 automatically. The shipper-rod 50 is
fitted to slide in bearings, as 49 and 51, formed on the yoke 12 and the upright 8,
respectively, of the head 3; a shipper-handle, 52, is fixed to the right-hand end of
the said rod by means of a pin, as 53, or otherwise; and a guide-arm, 54, is similarly
fixed by a pin, 55, to the left-hand end thereof. The forked end, 56, of the arm 54
engages the guide-pin 57, that is fixed in the end of the yoke 12 to prevent rotation
of the rod 50. A collar, 58, is fixed to the rod 50 by a set-screw, 59; and a
retracting-spring, 60, is carried on the said rod between the bearing 51 and said
collar 58. The belt-shipper 61 is carried on the said rod 50, to which it is or may
be fixed by a pin, as 62. The lower end or catch, 63, of the shipper-handle 52 is
designed to engage the hook-end, 64, of the knock-off pawl 65; which pawl is
pivotally supported at 66 on the bracket 67, that is fixed to the main-bed B by
screws as shown. Said bracket has a hub or boss, 68, formed thereon, which is
bored to receive the plunger 69 and the spring 70, that are provided for the purpose
of holding the pawl 65 normally in the position shown in Fig. 4 of the drawings.
The knock-off rod 71, for disengaging the pawl 65 from the catch 63, is carried in
a bearing, 72, which is formed therefor on the bracket 67, and in another and
similar bearing, 73, which is formed on a bracket, 74, that is fixed to the main-bed
by screws as shown in Figs. 2 and 6. A spring, 75, is carried on the rod 71
between the bearing 72 and the collar 76, which collar is adjustably fixed to the

page_text: said rod by means of a set-screw, as 77; said spring being provided for the purpose
of holding the said rod 71 normally in the position shown in Figs. 2, 4 and 6, with
the adjustable stop-collar 76 against the bearing 73; the collar 78 being secured by
a set-screw, as 79, in a well-known manner. A stop-arm, 80, through which to
actuate said rod, is adjustably secured to the rod 71 by means of a clamp-screw, 81,
in a well-known manner.
Referring to Figs. 5, 6 and 12, the breech of the barrel, C, to be drilled, is first
fitted to run closely within the sleeve or bushing 82, which is removably-fixed in
the hub, 83, of the barrel-rest 84; this rest is fitted to slide on the ways of the
main-bed B, and is provided with a shoe or gib, 85, and several set-screws, as 86,
for adjusting said rest to its ways, and for taking up any wear, as shown in Fig. 13.
Said rest is also furnished with the usual stamps, as 87 and 88, (secured by
screws 95,) which are provided with the nuts 89 and 90, to receive the threaded
ends of the binding-screws 91 and 92, respectively, the said nuts being provided
with pins, as 93, Fig. 6, to prevent the same from turning; a portion of the rest is
shown cut away on each side, as at 94, Figs. 6 and 13, to allow of the clamping of
the said straps 87 and 88 to the ways f and g. A projection, 96, is formed on the
under side of the barrel-rest bed, and is bored to form a guide or rest for the feed-
screw 46, and also for the large oil-pipe 158, hereinafter described. A drill-
guide, 97, is fitted tightly in the bore of the bushing, 82, of the barrel-rest, for
guiding the point of the drill at the beginning of a bore. Referring to Figs. 5, 6, 11
and 12, it will be seen that the bed, 100, of the drill-carriage is fitted to slide on
the ways, and 9, , of the main-bed B, and is furnished with the usual shoe or gib 101,
the set-screws 102 for said gib, and with the usual straps, 103, secured thereto
by the holding-screws 104. The said bed 100 has thereon a hub, 105, suitably
formed for receiving the drill-holder 106, the stem or shank, 107, of which is
inserted in the bore of said hub, with the flange, 108, thereof bringing up against
the forward end of the hub; the holder 106 is firmly held in place by the screw 109.
To prevent the said drill-holder from turning in the hub 105, a slot or groove, 110,
is formed in the shank, 107, thereof, and a screw, 111, is provided, whose point
engages said slot and thus prevents said holder from turning. See Fig. 12. The
holder 106 is bored to receive the shank, 130, of the drill 112, and is split on one
side for a portion of its length to provide for the clamping of the drill in the holder
by means of suitable clamp-screws, as 113; a push-screw, 114, is provided to force
open the sides of the drill-holder when the drill is to be removed.
The drill-carriage, when disconnected from the feed-screw, may be moved
rapidly forward and backward by hand, as when setting the machinery ready for
usc, or may be fed slowly forward at the proper speed for drilling by means of
the aforesaid feed-screw 46 and suitable means on said carriage for engaging said
screw. As shown in its preferred form in the drawings, said means consists of the
worm-gear 117 engaging said screw, and devices for clamping and releasing said
gear, and for turning the same by hand. The hand-wheel shaft 115, (see Fig. 11,)
is carried in a bearing, 116, formed on the carriage, 100, and the worm-gear 117
(preferably made of bronze) is keyed or otherwise removably fixed to the inner
end of the said shaft; the hand-wheel, 118, being similarly secured to the outer
end thereof. Said worm-gear constitutes a revolving nut, and also a feed-
pinion, and is in constant engagement with the feed-screw 46; so that by turning
the hand-wheel 118 the carriage may be moved forward or backward
desired, the screw serving as a rack, and the worm-gear as a pinion. For
causing the said gear 117 to serve as a feed-nut, some suitable clamping devices
are provided therefor, which may be as follows:-A clamp-screw, 119, is fitted
into a threaded bearing, 120, formed on the bed 100 in alignment with the
bearing 116. In practice, the threaded part of said bearing may be a bushing
or nut, as 121, that is firmly fixed in the said hub or bearing 120. A friction-
plate, 122, is carried on the inner end of the screw 119, and a friction-disk, 124,
(preferably made of leather,) is fixed to the plate 122. A lever or handle, 126,
is firmly fixed to the outer end of the clamp-screw 119 by means of a binding-
as

page_text: •
screw 127; by means of these devices the operator may readily clamp and
unclamp the worm-gear 117, between the said friction-washer 124 and the
flange 128 of the bearing 116, thereby preventing said gear from turning; con-
stituting it a feed-nut for operating the drill-carriage.
A lug, or projection, 129, is located on the bed 100 to strike the aforesaid
stop-arm 80 on the completion of the drilling, and through the rod 71 to
disengage the pawl 65 from the catch 63 of the shipper-handle 52, whereupon
the spring 60 throws back the rod 50 and ships the belt D from the driving
pulley 20 onto the loose pulley 18, thus stopping the machine.
The drill 112 is especially designed for use in my improved drilling machine;
the construction thereof will be best understood by referring to Figs. 15 and 16.
The drill is truly formed, and in a general way is similar to the ordinary two-
fluted drill. One of its two grooves or flutes 135 and 136 is continuous
throughout the entire length thereof, as shown (partly in dotted lines) in Fig. 15.
The groove 135, besides being continuous. throughout the length of the drill, is
covered or closed by a strip of sheet-metal, as 137, which is dovetailed into the
edges of said groove and then soldered to prevent leakage, thus forming a
covered channel for the passage of oil throughout the entire length of said drill,
from the interior of the holder 106 to the face of the bore being made.
The means for supplying the cutting edges of the drill with oil consists of an
ordinary pump, as P, Figs. 3, 4, and 14, suitably connected by piping, through
which oil may be conveyed to the drill.
The pump P consists of an ordinary pump-case or box 140, which is shown
secured by screws to the main-bed B at the left-hand end thereof, and furnished
with a removable cover, as 141. A shaft, as 142, provided with a pulley, 143,
adapted to be driven by means of a suitable belt (not shown) carries the usual
driving gear 144, located within the case 140, and which, as shown in Fig. 14,
meshes with and drives the driven gear 145, that is carried on a shaft or stud, 146,
also journaled in the frame or case of the pump.
an
A suitable oil-tank, as T, Fig. 2, is usually located about as shown in said fig.,
and has a partition wall, 147, dividing said tank into two divisions;
opening, 148, in the said wall allows the oil to overflow from the part "t" of
the tank into the main division thereof. The tank-cover, 149, has thereon a
strainer, as 150, perforated at 151, for separating the coarser chips or cuttings
from the oil drained from the machine; the said oil, and the finer chips mixed
therewith, pass through the strainer at 151, and through the opening, 152, in the
cover 149, into the chamber t of the tank. The fine chips settle to the bottom, as
indicated at 153, and the oil gradually rises until it reaches the level of the
overflow opening 148, through which it passes into the main division T of the
tank. A suction-pipe, 154, reaching nearly to the bottom of the tank T, as
shown in Fig. 2, is connected, as shown in Fig. 4, with the pump P. An outlet-
pipe, 155, connects the said pump with the opening or oil-passage, 156, formed in
the head 3, (Figs. 3, 8, and 9,) which passage is connected by a suitable pipe-
joint, as 157, Fig. 9, with the large conveyor-pipe 158, that is supported at its
outer end by the boss or guide-bearing, 96, of the barrel-rest bed 84.
The guide-
bearing 96, shown best in Figs. 12 and 13, is perforated as therein indicated at 98
for the feed-screw shaft 46 and also at 99 for the aforesaid tube 158, thus
maintaining the parallelism of said shaft and tube. As shown in this fig., a
smaller conveyor-pipe, as 159, is fitted to slide closely within the pipe 158, thus
connecting the pipe 158 with the oil-passage 160, formed in the carriage-bed 100;
through which passage the oil passes into the hollow stem, 107, of the drill-
holder 106, and thence through the covered channel, 135, of the drill 112, to the
cutting-point thereof.
An oil-guard, 165, Figs. 10, 11, and 12, rests on the bed B as shown in said
figs., and has the projections 166 formed on the inside thereof for the partial
support of the funnel 167; said funnel is also furnished with the funnel-holder 168,
which is provided with a bushing, 169, fitting the drill 112, said bushing having

page_text: a projection, 170, fitting the groove 136 of said drill. Said funnel-holder is
furnished with a pin, as 171, and the bushing 169 has a groove, 172, cut in the
periphery thereof, in which said pin engages for securing the said bushing in said
holder, and for allowing said bushing to turn with the drill, the projection 170
thereof acting as a driver therefor. By this means the funnel is securely held in
place, without materially wearing the drill. When the carriage is run fully back,
the drill is withdrawn from the funnel and oil-guard, and leaves the funnel free to
be removed.
In the general views, Figs. 1 and 2, some details, owing to the intricacy of the
mechanism, are not designated by reference characters; reference being had, in
all such cases, to the corresponding and enlarged views, Figs. 3 to 16, inclusive.
In preparing the machine for use, the operator secures a suitable-sized chuck, 33,
to the spindle 10; fixes in place a guide-bushing, 82, corresponding to the barrel
to be drilled, and provides the drill-guide 97 fitting in one end of said bushing as
hereinbefore described; and puts in place the drill and clamps it firmly into the
drill-holder 106, setting the carriage at the extreme right-hand of the bed, as
indicated by dotted lines in Fig. 2; the barrel-rest being also moved toward
the right-hand sufficiently far to withdraw the bushing 82 some distance off from
the barrel. Next, the gun-barrel to be drilled is fixed in the chuck 33 by means
of a clamp-screw 34, and the barrel-rest is moved towards the left-hand to carry
the large end of the barrel, as indicated in Fig. 12. It will be understood, of
course, that the arrangement of the barrel C may be reversed, the hole being
drilled from the small end instead of the large end, provided the chuck and socket
for supporting the same are suitably constructed therefor. The barrel being in
place and the rest set for carrying the same, the clamp-screws. 91 and 92 are
tightened to firmly hold said rest; next, the oil-funnel is put in place and the
drill-carriage is moved forward by means of the hand-wheel and pinion thereof
until the drill passes through the funnel and through the bushing 97 to the end of
the barrel C. The machine now being started by hand by means of the handle 52,
rod 50 and the shipper 61 whereby the belt D is shifted from the loose pulley 18
onto the driving pulley 20, the clamp-screw 119 is turned by means of the
handle 126 to firmly clamp the revolving nut 117 in the carriage, thus causing
the feed-screw to move forward the carriage at a speed determined by the
described feed-gearing intermediate to the spindle 10 and said feed-screw.
As the carriage moves forward, the drill is forced against the barrel and cuts
its way into the same, being lubricated by the current of oil forced by
the pump P through the pipes 158 and 159, the channel 160, and through the
drill itself, to the face of the bore, as herein before described. The pump P being
a forcing-pump of positive action, the current of oil or other lubricating fluid
employed is driven to the face of the bore in a positive manner, thereby furnishing
effective means for driving the chips through the open channel or groove, 136, of
the drill 112, until the chips mixed with the discharge oil or fluid are delivered
into the funnel 167, from thence they drop through the opening in the bed B
onto the screen 151 of the oil-tank. As the drill-carriage is driven forward as
described, the conveyor-pipe 159 is forced forward within the larger conveyor-
pipe 158, thus by a telescopic arrangement providing a constant communication
between the fixed pump and the travelling drill-carriage. The conveyor-pipe 159
being parallel with the drill and with the ways of the frame, serves as a piston
on which the forced current of fluid acts to normally drive the carriage backward
toward the right-hand. This action, in connection with the feed-screw acting on
the clamped-nut 117, holds the drill-carriage firmly between two opposing forces,
thus rendering the forward movement very firm and steady, as required for
drilling accurately formed holes. On the drill-carriage reaching the forward end
of its stroke and completing the drilling of the barrel, the stop 129 strikes the
stop-arm 80, (this arm having been previously set on the rod 71 in a suitable
position therefor,) and, as hereinbefore described, disengages the catch 65 from the

page_text: shipper-rod arm 52, thereby permitting the spring 60 to shift the belt D from the
driving pulley 20 onto the loose pulley 18 and thus automatically stop the machine.
The operator now loosens the clamp-screw 119, and taking hold of the hand-
wheel 118, runs back the carriage to the position shown by dotted lines in Fig. 2,
thereby withdrawing the drill from the barrel. Next, the clamp-screws 91 and 92
are loosened and the barrel-rest moved toward the right-hand; after which the
clamp-screw 31 of the chuck 33 is loosened and the barrel taken ont. The
machine is then in position ready for a repetition of the above-described
operations.
The drill-guide 97 is made of considerable length relative to the diameter of the
drill, as will be seen from Fig. 12. It is also made to closely fit the drill, and is
set in accurate alignment with the axis of the barrel-carrying spindle, so as to
afford a guide for the long and slender drill and thus prevent any springing of the
drill from affecting the direction of the drilling.
The frictional surface of the revolving nut 117 being in the plane of the carriage
movement, and the nut being set or fixed by friction only, any material increase of
the resistance to the drill over the normal feeding power will cause the slipping
of said revolving nut between its clamping faces so as to reduce the feeding
movement and thus allow the obstruction to be overcome. This provision
accommodates the action of the machine to variability in the character of the
metal of the barrel C, so that when meeting harder portions or spots of the metal,
the rate of drilling will be correspondingly reduced.
A practical effect of operating the main spindle 10 by means of the frictional
driving apparatus and in connection with drill-feeding mechanism actuated from the
spindle itself, is to gradually reduce the velocity of the spindle (and, of course,
the cutting velocity,) on the drill meeting with increased resistance, as for instance,
on reaching a harder portion of the barrel C. A slight increase in the resistance
encountered by the drill causes the pulley to slip between the collars 19 and 24,
the friction caused by the slipping increasing slightly the driving power of the
pulley, so that the cutting speed is slightly reduced and the cutting pressure
simultaneously slightly increased, thus automatically regulating the action of the
machine to the particular character of the metal, and thereby attaining the very
highest degree of efficiency throughout the whole operation of drilling the barrel.
This feature of the invention is further extended by the combination with the
frictional driving mechanism of the frictional driving apparatus of the feed-carriage,
thus providing two independent frictional apparatuses, one for the spindle and one
for the drill-carriage, which apparatuses co-act for the attainment of one result;
it being understood that the machine herein described is peculiarly organized for
the especial purpose of securing the utmost efficiency, precision and economy.
One peculiar result of the organization shown and described is the automatic
relieving of obstructions due to the clogging of the chips at the point of the drill.
When, during the operation of the machine, the tough steel chips pack together at
the point of the drilling-tool, the forced current of oil increases the pressure on
the drill, so that both the drill and the tube 159 act as pistons for retracting the
drill-carriage; this slightly withdraws the drill from the face of the bore, thereby
dislodging the obstruction, which is immediately washed out by the high-pressure
current, leaving the drill free to be advanced again by the feed mechanism; the
retreating movement of the carriage being due, as will be understood, to the
pressure on the piston increasing to a point sufficient to overcome the friction on
the sides of the revolving nut 117. By this means a positive-acting pump co-acts
with the frictional feed mechanism to not only clear the bore of chips while the
machine acts normally, but to also clear away obstructions arising from packing of
the chips, experience showing that such obstructions will occasionally happen.
By means of this improved machine, it is found practicable to drill a small-bore
rifle-barrel by one continuous operation, without stopping the machine or with-
drawing the drill from the barrel to be cleared of chips; since the forced current

page_text: of oil conveyed as herein described appears to forcibly dislodge and carry out the
chips as fast as they are formed, thus keeping the bore free of obstruction,
keeping the barrel cool, and lubricating the cutting lips of the drilling-tool.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. In a gun-barrel-drilling machine, the combination with a frame having ways
for a barrel-rest and a drill-carriage, of the barrel-carrying spindle and the feed-
screw supported by bearings in substantial alignment. with said ways, the barrel-
rest constructed to support the outer end of the barrel and to be clamped to the
frame and having a drill-guide, the drill-carriage fitted to slide on said ways and
carrying the drill in alignment with said drill-guide and barrel-carrying spindle,
and means for engaging and disengaging the carriage from the feed-screw.
2. In a gun-barrel-drilling machine, the combination with the frame, the barrel-
carrying spindle, and a feed-screw, of the barrel-rest movable on said frame and
constructed to carry the outer end of the barrel and provided with a drill-guide,
of the drill-carriage connected and fitted to slide on said frame and adapted to be
actuated by said screw, a drill carried by said carriage in alignment with said
drill-guide and spindle, means forcing lubricating fluid in through the drill and out
through the drilled bore and drill-guide, and a funnel substantially as described
covering the drill adjacent to the guide for catching the discharged chips and
lubricating fluid.
3. In a gun-barrel-drilling machine, the combination with means for rotating the
barrel, and with the movable barrel-rest adapted to engage the outer end of the
barrel, of the drill-guide 97 closely fitting the drill and set in alignment with
the axis of the barrel, the drill fitting said guide and having a covered channel to
the point thereof, a carriage carrying and feeding the drill, and means supplying
lubricating fluid to the drill-channel, whereby the drill is accurately guided and
the point thereof supplied with fluid, and the drill-guide kept free of obstruction.
4. In a gun-barrel-drilling machine, the combination with a drill-carriage and
the drill carried thereby, of a bushing fitted to slide on the drill in engagement
with the grooves thereof, whereby the bushing is revolved with the drill, and a
funnel substantially as described supported on the revolving bushing in longitudinal
engagement therewith, whereby the bushing is slid on the drill.
5. In a gun-barrel-drilling machine, the combination with the drill-carriage
having the passage-way 160, of the drill-holder removably fixed in the drill-
carriage and having its interior communicating with said passage, and the channel-
drill removably fixed in said holder, whereby communication is made between said
passage way and the channel of the drill.
6. In a gun-barrel-drilling machine, the combination with the drill-carriage, of
the hollow drill-holder removably fixed therein, the channeled drill removably
fixed in said holder, the conveyor-pipe connected to the carriage, and a passage
leading from said pipe to the interior of the drill-holder, whereby communication
is made between the conveyor-pipe and the point of the drill.
7. In a gun-barrel-drilling machine, the combination with the frame having
ways for the drill-carriage and having a feed-screw parallel with said ways, of the
drill-carriage 100 fitted to slide on said ways and carrying the drill, a revolving
nut supported on said carriage in engagement with the feed-screw, means for
revolving said nut by hand for traversing the carriage, and a clamp for frictionally
setting the revolving nut to feed forward the carriage with a limited power,
whereby the feeding movement is retarded by increased resistance to the drill.
8. In a gun-barrel-drilling machine, the combination with the frame having
ways for the barrel-rest and the drill-carriage, of the barrel-carrying spindle, the
feed-screw and the fixed conveyor-tube set in alignment with said ways, the
barrel-rest fitting said ways and having guide-bearings for said feed-screw and
conveyor-pipe, the drill-carriage furnished for operation from the feed-screw and

page_text: carrying the drill in alignment with the spindle, and a sliding conveyor-tube
connected to the carriage and fitting the fixed conveyor-tube, said sliding tube
constituting a piston normally resisting the feeding movement of the carriage.
9. In a gun-barrel-drilling machine, the combination with the head carrying the
spindle and having a channel supplied by a pump, and with the drill-carriage
carrying the channeled drill in alignment with said spindle, of the two conveyor-
tubes, one fixed to the head and communicating with the channel therein, and the
other fixed to said carriage and communicating with the drill-channel, said tubes
being telescoped one within the other and forming an extensible connection
between the pump and the drill.
10. In a drilling machine, the combination with the head and the spindle
mounted therein, and with the drill fed to work by feed mechanism substantially
as described actuated from said spindle, of the driving pulley mounted to turn
freely on the spindle between a fixed collar and a sliding collar, and a spring
acting on the sliding collar to clamp said pulley for frictionally driving the spindle,
whereby the speed of the spindle is reduced on the drill meeting with increased
resistance.
11. In a drilling machine, the combination with means supporting and rotating
the piece to be drilled, of the drill-carriage carrying the channeled drill, a positive-
acting pump communicating by connections substantially as described with the
drill-channel, and frictional feed mechanism forwardly actuating the drill-carriage,
whereby an obstruction in the bore raises the pressure to retract the drill and
dislodge the obstruction.
Dated this 11th day of February 1891
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.