IMPROVE- MENTS IN MACHINERY FOR SERRATING THE EDGES OF REAPER KNIVES, SICKLES AND SIMILAR ARTICLES, AND FOR CUTTING FILES AND RASPS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Henry Theaker at the Office of the
Commissioners of Patents on the 1st November 1883.
HENRY THEAKER of Sheffield in the County of York, Engineer, "IMPROVE-
MENTS IN MACHINERY FOR SERRATING THE EDGES OF REAPER KNIVES, SICKLES
AND SIMILAR ARTICLES, AND FOR CUTTING FILES AND RASPS"
My Invention relates to improvements in the construction of Machinery for
serrating the edges of Reaper Knives, Sickles, and other similar articles, and also
for cutting the teeth of files and rasps. Broadly speaking my improved machine
consists of a standard erected upon a base fitted with a horizontal sliding table on
which the work is fixed; the top of the standard carrying a vertical slide and
toolholder, which is raised by the action of a revolving Cam, and is forced down
again by the action of a spiral spring, the power of which can be adjusted by a
handwheel and screw. The cam shaft passes through the head of the standard and
is driven by a pulley running loose upon the shaft but which can be connected or
released by a simple clutch motion preferably worked by the foot.
An eccentric driven by the same shaft is connected to the lever of a ratchet
feed-wheel secured to a shaft which revolves in an eccentric bearing near the base
of the standard; on the other end of the shaft which projects from the eccentric
bearing above the horizontal table, is fixed a grooved friction wheel, engaging
with a correspondingly grooved plate secured to the sliding table.
The friction wheel may be instantly thrown in and out of gear with the plate
by means of a weighted lever which is attached to the eccentric bearing and is
under the control of the workman. Thus when the clutch motion is thrown into
gear the cam revolves and its periphery coming in contact with a projecting stud
upon the vertical slide, raises it to the extent of the throw of the cam, compressing
the adjustable spring, which again forces down the slide directly the stud passes
the apex of the cam-The pawl of the ratchet being moved forward at each
revolution of the eccentric, forces round the ratchet wheel, and also the friction
wheel, thus moving forward the horizontal table with the work secured to it, and
when the requisite number of teeth are cut, a slight movement of the clutch lever
detaches the pulley and stops the machine, at the same time the workman raises
T

page_text: the friction wheel out of gear with the table, which is either drawn back by
means of a weight, or similar devico, automatically, or it may be forced back by
hand.
The vertical slide with the toolholder may be permanently fixed at any desired
angle, or may be made to swivel to any angle and be secured by ordinary means.
To gradually increase or diminish the pitch of the tooth (as towards the point of a
tapered file for example) I bore the centrehole of a suitable ratchet feed wheel, as
much out of the centre as is requisite, and this simple expedient accomplishes the
desired object in a very satisfactory manner. For cutting the teeth and serrating
the edges of Sickles, and other similar curved articles, a moveable sweep is fixed
in front of the machine, in which the sickle is secured by means of the tang, and is
thus brought automatically under the cutting tool.