IMPROVEMENTS IN MACHINERY FOR TAPPING SCREW THREADS." MACHINERY FOR TAPPING SCREW THREADS
Year: 1875

page_text: LETTERS PATENT to Robert Taylor, of Oldham, in the County of
Lancaster, Machinist, for the Invention of "IMPROVEMENTS IN
MACHINERY FOR TAPPING SCREW THREADS."
MACHINERY FOR TAPPING SCREW THREADS.”
PROVISIONAL SPECIFICATION left by the said Robert Taylor at the
Office of the Commissioners of Patents, with his Petition, on the
28th January 1875.
I, ROBERT TAYLOR, of Oldham, in the County of Lancaster, Machinist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
MACHINERY FOR TAPPING SCREW THREADS," to be as follows:-
My improved machinery is particularly adapted for tapping screw
threads into washers or other articles secured to shafts by set screws, but
it may be applied for other purposes.
The screw tap is secured to a spindle, which is turned round alter-
nately in contrary directions by means of one strap and three pulleys.
One pulley is keyed on the spindle, another is loose thereon, and the

page_text: third is loose on the bush in which the spindle revolves; this last pulley
has internal teeth gearing into a carrier pinion, which gears into a pinion
keyed on the spindle. When the driving strap is on the fast pulley it
turns the tap slowly round to cut the screw thread, and when it is on
the third pulley it turns the spindle quickly round to unscrew the tap.
The article to be tapped is mounted on a slide that is moved to and
fro on the table as usual, and the strap is moved from the first to the
third pulley by a rod connected to the slide acting on an elbow catch
lever by which the strap guide lever is held, and the strap is brought
back again by a link connected to the slide and to the strap guide
lever.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Taylor in the Great Seal Patent Office
on the 7th July 1875.
- TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
TAYLOR, of Oldham, in the County of Lancaster, Machinist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
, Letters Patent, bearing date the Twenty-eighth day of January, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-eighth year of Her reign, did, for Herself, Her heirs and suc-
éessors, give and grant unto me, the said Robert Taylor, Her special
licence that I, the said Robert Taylor, my executors, administrators,
and assigns, or such others as I, the said Robert Taylor, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
MACHINERY FOR TAPPING SCREW THREADS," upon the condition (amongst
others) that I, the said Robert Taylor, my executors or administrators,
by an instrument in writing under my, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
♥..

page_text: are made in the ordinary manner.
The spindle d is turned round alter-
nately in contrary directions by the driving strap / and the pulleys i
and; the former is keyed on the spindle, and the latter is loose on the
bush k, which is held fast in the headstock c, and in which one end of
the spindle revolves. The inside of the pulley j is furnished with an
internal spur wheel j', gearing into the carrier pinion 2, which revolves
on a stud fixed in the flange k' of the bush k, and the pinion gears into
and drives the spur wheel d', keyed on the spindle d. Between the
pulleys and jis the pulley m, loose on the spindle.
The article to be tapped, shewn at n in Figs. 1 and 3, is placed upon a
stud o¹ in the bracket o, which is bolted to the bracket p, secured to the
slide g; this stud and the brackets are adjustable to suit the various
sizes of the articles to be tapped. To the slide 9 is also fixed the
adjustable rod f', the end of which acts on the pendant arm of the
elbow catch lever q, which takes on a pin projecting from the strap
guide lever 1. Near the upper end of this strap guide lever is the
stud for the upper end of the jointed link 8, the lower end of which
passes through the stud 9' fixed to the slide g. At the top of the strap
guide lever is a slot to receive the end of the strap fork t, which is
fixed in the starting rod t, passing through guides fixed to the caps of
the spindle d. The starting rod can be worked by hand to start or stop
the machine.
The mode of operation is as follows, and the Drawing represents the
parts in the positions they occupy when the driving strap h is on the
fast pulley i, and the spindle d is revolving at the proper speed for
tapping the screw :-As soon as the operator has put the article to be
tapped on the stud o' in the bracket o, he pushes the slide g forward
until the end of the screwing tap e enters the hole that had previously
been bored in the article to be tapped. The tap then gradually screws
itself into the hole, and draws the slide 9 towards the headstock c, a
thereby bringing the end of the rod f¹ against the elbow catch lever q,
which is thus lifted off the pin in the strap guide lever 7. As soon as
this lever is released the counterweight on its horizontal arm moves the
driving strap on to the pulley j, and the spindle d is then turned round
at an accelerated speed and in the contrary direction to unscrew the tap :
out of the hole previously tapped. During the unscrewing of the tap
the slide is pushed back, and the jointed links then brings the strap
guide lever back to its original position, where it is held by the catch q,
g

page_text: and the parts are then in position for repeating the operations as soon as
the tapped article has been taken off the stud o³ and an untapped one put
in its place.
Having thus stated the nature of my Invention and described the
manner of performing the same, I declare that I claim,―
First. The application of the internal toothed wheel j¹, combined with
the pinion and wheel d', for reversing the motion and accelerating the
speed of the spindle of a screw cutting machine, as shewn and
described.
And, Secondly. The improved combination of lever, links, and catch
for stopping and starting screw cutting machines, as shewn and
described.
In witness whereof, I, the said Robert Taylor, have hereto set
my hand and seal, this Fifth day of July One thousand eight
hundred and seventy-five.
DATTITm