IMPROVEMENTS IN FORMING THE POINTS OF AUGERS AND IN CUTTING THE SCREW THREAD OR THREADS THEREON
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by John William Simpson and John
MoFie at the Office of the Commissioners of Patents on the 11th October
1883.
JOHN WILLIAM SIMPSON and JOHN M°FIE both of Rutherglen in the County of
Lanark, North Britain, "IMPROVEMENTS IN FORMING THE POINTS OF AUGERS
AND IN CUTTING THE SCREW THREAD OR THREADS THEREON
"
This Invention, which relates to improvements in forming or shaping the points
of the blanks of screw augers preparatory to cutting the screw thread or threads
thereon as well as to improved apparatus for cutting the said screw thread or
threads, consists as follows:-
In a headstock a bollow mandril is fitted for the reception of an auger blank.—
The outer end of this mandril carries a chuck for gripping the blank into its proper
central position-The mandril is arranged to be driven at two different speeds,
namely, at a fast speed by means of a driving belt or by spur gearing during the
time when the point of the auger blank is being shaped preparatory to cutting the
screw thread or threads thereon.-It is arranged to be driven at a slow speed
during the time when the screw thread or threads is, or are being cut on the said
point. A clutch being provided for engaging the mandril with the slow speed or
fast speed gear as required.
In slide rests there are mounted two shafts, ou one of which a rotating file,
which may be either conical or cylindrical, is placed.-This file is rotated by a belt
so as to produce in it a surface speed different from the surface speed of the point
of the auger blank so that it files the blank into the requisite shape during the
time when both the blank and the file are rotating.
So soon as the point has been brought to the necessary shape by the action of
the rotating file, the said file is by operating the screw or screws of the slide rest
brought out of contact with the point of the blank and the other slide rest carrying
the rotating cutter for the screw or screws is brought into contact to operate upon
the auger point and so soon as this contact has been made the mandril carrying
the auger blank is placed in the slow speed gear. Both the rotating screw thread
cutter and the mandril are now put into operation, the cutter being pressed by
the slide rest against the point so as to cut the screw thread thereon and
[Price 2d1

page_text: simultaneously therewith the headstock carrying the mandril is put into gear with
the screw traversing mechanism by means of which it is travelled horizontally along
the bed of the machine at a speed corresponding to the pitch of the screw thread
or threads.
An indicating dial or dials is or are used for ensuring that the different parts of
the mechanism are brought to their several relative positions so as to ensure the
necessary accuracy of the work done on the auger points.
A rack and pinion or its equivalent is also provided for the purpose of moving
the headstock carrying the auger point back out of the position it normally
occupies, during the time when the blank is being adjusted and straightened in the
chuck. After the blank is adjusted and straightened the headstock and the parts
it carries are returned to their normal position.
By means of the mechanism hereinbefore described the screw thread or threads is,
or are, or may be cut on the auger point during one slow revolution of the auger
point and for the purpose of finishing off and smoothing so as to prevent the cutter
leaving any ridge upon the screw thread, a rapidly revolving hand gearing is
employed for imparting a quick speed to the mandril during its last few revolutions
of screw cutting.