IMPROVEMENTS IN DRILLING MACHINES
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by James Nelson at the Office of
the Commissioners of Patents, with his Petition, on the 28th April
1875.
I, JAMES NELSON, of Sunderland, in the County of Durham, Engincer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
DRILLING MACHINES," to be as follows:-
My Invention consists in constructing drilling machines as follows:-
Upon one end of a slotted base plate I mount a vertical socket which is
bored to receive a cylindrical part of a bracket herein-after mentioned.
The said cylindrical part is turned externally to fit the vertical socket,
and bored internally to receive the tube and carrier of the drill spindle.
On the top of the tube and carrier is a horizontal bevel wheel, either cast
in one piece therewith or fixed thereto, while at the bottom are collars to
prevent the tube rising. Within the tube is a sunk key which fits into
a vertical groove in the drill spindle; this spindle is screw-threaded
externally and has a hole at its lower end to receive the drill.
The upper part of the bevel wheel is formed with a concentric dove-
tailed or mitred recess in which the lower portion of an upper horizontal

page_text: bevel wheel fits. This upper wheel is fixed to or formed in a piece with
the cover of the drill spindle, and this cover is formed with a female
thread commencing at its lower end and extending as far up as may be
desirable to form a nut to the drill spindle; this cover also serves to
steady the spindle when at work. On the top of the cover is a cap.
E
Passing through a bearing in the bracket herein-before mentioned is a
horizontal hollow spindle, having at one end a bevel pinion to gear into
the bevel wheel first hercin-before mentioned, and at the other end a
handle for driving it so as to rotate the drill. Another spindle passes
through the hollow of the last-named spindle, and carries at one end a 1
bevel pinion to gear into the upper or second bevel wheel, and at the
other end a handle for driving it, so as to rotate the cover and thus cause
the drill to move up or down.
The numbers of the teeth of the two bevel wheels and corresponding
pinions are slightly different, so that if both the pinions are rotated the
same number of revolutions in the same direction, one wheel will move
at a different speed to the other, and as the cover or nut of the drill
spindle will thus rotate at a different speed to this 'spindle, the latter
will be screwed downwards and the drill will consequently be fed.
The operation or working of the machine is as follows:-The slotted
base plate is fixed to any convenient thing, and the bracket which
carries all the working parts is turned round in the vertical socket to any
convenient angle and then fixed by a pinching screw. The drill is then
brought down to its work by rotating the handle of the upper pinion
which gives motion to the cover or nut. When the drill has reached its
work this handle is turned or doubled down, so that a catch thercon
takes into the handle of the lower pinion. This latter handle is then
turned; both pinions and both wheels will thus be rotated together, and
while the drill is thereby caused to rotate a gradual advance or feed
thereof is effected owing to the difference in speeds of the two wheels as
above described.
Instead of fastening the two handles together by a catch as above
stated the two pinions or their spindles may be fixed together by a
friction nut, and in this case the drill may be brought to its work by a
hand wheel on the cover of the drill spindle.
Drilling machines constructed as above described are very compact,
the height from the bottom of the base plate to the top of the cover

page_text: being only about 2 times the travel of the drill. As the tube of the
spindle revolves with this spindle there is no wear of the spindle, and as
the spindle in its work never or rarely projects beyond the bottom of its
tube it is thoroughly and equally guided during the whole of its travel,
and is not exposed to dirt or to damage.
Although I have described the Invention as applied to hand or
portable drilling machines, I consider that the arrangement in which a
drill spindle works in a revolving tube and never projects therefrom, and
is therefore equally guided during the whole of its travol, may be applied
with advantage to all kinds of drilling machines, and so may the mode
of feeding the drill.