IMPROVEMENTS IN TURNING LATHES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by James Garvie at the Office of the
Commissioners of Patents on the 9th September 1880.
JAMES GARVIE, of 5, New Street, Bishopsgate Without, in the County of
Middlesex, Engineer. "IMPROVEMENTS IN TURNING LATHES."
This Invention relates to a peculiar combination and arrangement of parts
constituting an improved lathe for turning regular and irregular work, and for
chasing or cutting screws.
The improved lathe may be driven in any well known manner, and be provided
with one or more heads, single or double geared, the whole being fitted on a suitable
bed or standard. When used for turning taper, circular, or irregular work, a pattern
is mounted on a bracket at the back of the lathe, which pattern is caused to swivel
when required on a pivot or centre, and is capable of adjustment and of boing fixed
in any desired position. Along this pattern slides a block or pin to which is
connected one end of a connecting rod, the opposite end of which rod is connected
by a tightening screw to the slide rest, mounted on a loose slide, which loose slide
moves freely across the saddle, the connecting rod being left free to work through
the loose slide when parallel work is required. AT slot is provided in the top of
the slide rest to receive the tool holder, which may be of any well known
construction, but I prefer to employ the arrangements hereinafter described. This
tool holder consists according to one arrangement of a vertical stud or pillar having
a T head on its lower end, fitting into the corresponding slot in the slide rest, and
free to be withdrawn at either side of the rest. A screw thread on the stud
receives a tightening nut for fixing the tool holder in the slide rest. A holo is
provided across the upper end of the stud to receive the tool, which is fixed by a
pinching screw. According to another arrangement, a capstan tool holder is
mounted so as to turn upon the upper end of a stud or pillar introduced into the
same T slot as the one previously referred to, spring or other catches being
provided for fixing the said capstan head in any desired position. Below the
capstan head there is secured to the stud or pillar in any suitable manner a plate
which serves for tightening the stud or pillar in position in its slot, and for carrying
the spring or other catches above referred to. In order to afford greater facility
for chasing screw threads of various pitches, and for rapidly changing from one
pitch to another, or from right to left handed threads, I employ a number of leading

page_text: screws of different pitches, so mounted in a moveable or adjustable holder, whether
made to slide or to turn on a centre, as to enable any one of the series to be brought
into gear as required, spring or other catches being provided for fixing the holder
in position. These leading screws are driven from the head of the lathe in the
ordinary manner, but in order to afford facility for changing from right to left
handed screws, I employ an adjustable quadrant carrying three pinions gearing into
each other. When the intermediate pinion is in gear with the screw, a right hand
thread is produced, and by simply shifting the quadrant so as to bring the third
pinion into gear with the screw, a left hand thread is formed, the quadrant being
fixed in either position by a tightening screw or otherwise.