A NEW OR IMPROVED MACHINE FOR GRINDING THE TOOLS USED IN TURNING OR SHAVING THE HEADS OF WOOD SCREWS AND OTHER SIMILAR ARTICLES
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by William Avery at the Office
of the Commissioners of Patents, with his Petition, on the 7th June
1864.
I, WILLIAM AVERY, of the Firm of James, Sons, and Avery, of Bir-
mingham, in the County of Warwick, Screw Manufacturers, do hereby declare
the nature of the said Invention for "A NEW OR IMPROVED MACHINE FOR
GRINDING THE TOOLS USED IN TURNING OR SHAVING THE HEADS OF WOOD SCREWS
AND OTHER SIMILAR ARTICLES," to be as follows:-
The tools used in turning or shaving the heads of wood screws and other
similar articles are kept in working order by being ground on one of their
ends, the grinding being effected in two planes inclined at an obtuse angle to
each other. This grinding is usually performed on an ordinary grindstone,
the tool being held by the workman, but it is scarcely possible to grind the
tool in this way with any nicety, and the object of my Invention is to effect
the grinding of the said tools with greater precision than is practicable by the
ordinary method.
My said Invention consists of a machine in which a grindstone is provided
with the means herein-after described for adjusting it with great precision,
and provided also with a holder in which the tool to be ground is fixed, and
by which the tool can be presented at the required angle to the grindstone,
and made to pass across the grinding surface. The lower half of the grind-
stone works in a water trough, the axis of the grindstone working in bearings

page_text: capable of sliding up inclines on either side of the said trough. The sliding
motion of the said bearings is effected by screws worked by a hand wheel.
The holder in which the tool is fixed while being ground is supported in a
frame which can slide in bearings on each side of the trough. The said
holder consists of a hollow cylinder, the axis of which is set at an angle with
the radius of the grindstone, the angle being that at which it is desired to
grind the planes at the end of the tool. The tool enters the cylinder at an
opening in its side, and is fixed by a wedge operated upon by a screw and
hand wheel. By means of another hand wheel the said holder or cylinder
may be made to perform when required a movement of partial rotation. The
frame which carries the holder is capable of being moved across the grinding
surface of the grindstone by means of a pinion which turns in bearings on the
said frame, the said pinion taking into a rack fixed to the trough. By means
of a hand wheel on the axis of the said pinion it can be made to rotate and
carry the holder across the grindstone. In using the machine the tool is fixed
in the holder, its precise position being determined by a stop or guide. The
grindstone is made to turn, and the tool is carried across its surface by means
of the rack and pinion described, one of the planes on the end of the tool is
thus ground. The holder carrying the tool is now made to partially rotate on
its axis, and the tool being then carried again across the surface of the grind-
stone the other plane on the end of it is ground. This process is repeated
until the tool is sufficiently ground.