IMPROVEMENTS IN KNIVES EMPLOYED IN WOOD-PLANNING MACHINERY, AND THE MODE OF GRINDING SAME, ALSO IMPROVEMENTS IN CERTAIN PARTS OF THE MACHINERY IN WHICH THEY ARE EMPLOYED
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Thomas John Clarke at the Office
of the Commissioners of Patents on the 23rd June 1880.
THOMAS JOHN CLARKE, of Aylestone Park, Leicester, in the County of
Leicester. "IMPROVEMENTS IN KNIVES EMPLOYED IN WOOD-PLANNING MACHINERY,
AND THE MODE OF GRINDING SAME, ALSO IMPROVEMENTS IN CERTAIN PARTS OF
THE MACHINERY IN WHICH THEY ARE EMPLOYED."
Heretofore thick knives have been used partly composed of steel and partly
composed of iron. Knives made in this manner are costly, and the steel much
injured with the process of welding.
According to the first part of my Invention in order to remedy these dis-
advantages I take a piece of hardened steel the required length & width, and
properly sharpened for its purpose as a knife; I then take a piece of soft steel or
iron the same length as the knife, but a little narrower, and bevelled on one edge
and slightly hollow on one side; I then clamp the knife next to the knife block or
holder with the steel or iron plate on the back of the thin steel knife, so that the
bevel edge of the soft steel or iron plate comes close to the back of the knife edge
to provent the knife from breaking when coming in contact with any obstruction,
such as knots or other hard substances in the wood.
The knives made in this way are much more easily sharpened, as they are only
about one sixth the thickness of those made of iron and steel in the old mode.
I also purpose to sharpen these and other knives used for cutting wood and
other like substances by passing them to and fro with a worm cut with a right
and left hand thread, so that the worm always being turned one way carries the
knife backwards and forwards on front of a grinding stone or emery wheel auto-
matically, and so grinds an equal and bevel edge, and therewith saving a great.
deal of time and labour.
My next part of the improvement is for a knife block or holder. These are
generally made with a dovetail, grove running from end to end of the block or
knife holder with several bolts-fitted-in-it. These bolts are used for holding the
knives firm to the block, and these bolts.are.frequently broken with hard substances.
coming in contact-with-the-knives, and the workmen suffer great inconvenience
and loss of time with having to remove several of the bolts before he can extricate
the broken one from the grove. According to my Invention in order to remedy

page_text: these disadvantages I make in my knife block or holder a short T shaped grove,
so that each bolt may be put separately into its own grove without the incon-
venience of removing others, and by this means I give additional strength to the
knife block or holder, as I get the full strength of metal around the steel shaft in
several places, wherein if the dovetail grove runs from end to end of the block or
knife holder the strength of the metal is so far removed that the pressure on the
wedgo shaped heads of the bolts crack the block or knife holder, and so causes an
accident when the machine is put in motion.