IMPROVEMENTS IN MACHINERY APPLICABLE TO GRINDING AND BRINGING TO AN EVEN SURFACE COPPER PLATES USED IN POTTERY ENGRAVING
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by the said Thomas Smith at the Office
of the Commissioners of Patents on the 24th March 1882.
THOMAS SMITH of Stoke on Trent in the county of Stafford "IMPROVEMENTS
IN MACHINERY APPLICABLE TO GRINDING AND BRINGING TO AN EVEN SURFACE
COPPER PLATES USED IN POTTERY ENGRAVING"
The preparation of copper plates for pottery engraving at the present time is
done entirely by hand. The following is a description of the process. Copper
plates are cut to the required sizes from sheets. The surface is then scraped so as
to remove all flaws; it is then well hammered to harden the copper, and also to
set it true, that being done it has then to undergo the most laborious part of the
work. Rubbing or grinding with stone and water. There are four different kinds
of these stones used, beginning with a rough one called Scotch grit, which removes
hammer and scraper marks. Afterwards pummice stone is used to remove the
cuts of the former, then two more stones are substituted which are still finer than
previous ones until the surface is gradually brought smooth enough for the
engraver.
Now my invention is designed to do this by machinery and consists in holding
the plates in frames of various sizes to suit the various sized plates beneath
successive stones and burnishers, both the frames and the stones or burnishers
reciprocating horizontally but at different speeds and in directions at right angles
to each other.
My experimental machine is of the following description. A series of ten frames,
most of them of different sizes to suit the sizes of plates required, are arranged
along.one gantry. One long shaft carrying a screw with a different pitch for each

page_text: frame gives them all, by means of nuts cast or fixed in each frame, a horizontal
reciprocating motion; the pitch of the screws being proportioned to the width of
frame so that each stone shall get to the edge of its plate at the same moment and
so that each frame travels just the width of the plate it carries. A rocking shaft
with a series of rocking arms, of adjustable length, linked with a hinged joint to
the stone carriers or rubbers, gives a transverse and much quicker horizontal travel
to the stones than the screwed shaft gives to the frames. The telescopic slides in
the arms regulating the length of travel. The stones or rubbers are weighted with
suitable weights. The plates are held in each frame centrally by two clamping
bars, bevelled to fit the edges of the plates, and worked by a right and left handed
screw.
The long screw is revolved by means of two ratchet wheels one for the right
and the other for the left hand motions. The ratchet lever between is provided
with two spring catches, one for each wheel, but only acts on one at a time,
carrying it round by the teeth one sixth at a time, giving the frames a very slow
motion. The self-acting reversing arrangement is gained by a link and weighted
lever travelling on a screw of the same pitch as that for the narrowest frame,
corresponding exactly with the travel of the other threads. The link presses on
the cranked lever which keeps the ratchet lever (by means of a finger) at work
.against one wheel. When it arrives at either end of the thread, it is caught by a
projecting peg, which throws the weighted lever over the centre, carrying the link
with it, which then bears on the opposite side of cranked lever, and so changes the
action of ratchet lever from one wheel to the other, reversing the screw shaft
instantly.
Water is supplied to each frame in a small stream or succession of drops. The
frames slope from front to back allowing the water to run into a long trough at
their lower ends.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Smith in the Great Seal Patent Office on the
23rd September 1882.
THOMAS SMITH of Stoke on Trent in the county of Stafford
"IMPROVEMENTS
IN MACHINERY APPLICABLE TO GRINDING AND BRINGING TO AN EVEN SURFACE
COPPER PLATES USED IN POTTERY ENGRAVING"
The preparation of copper plates for pottery engraving at the present time is
done entirely by hand. The following is a description of the process Copper
plates are cut to the required sizes from sheets the surface of them scraped so as
to remove all flaws, and then in order to harden the copper and set it sufficiently
true, they are well hammered that being done the plates undergo the most
laborious part of the process that of rubbing or grinding with stone and water
There are four different kinds of stones used beginning with a rough one called
Scotch grit which removes hammer and scraper marks. Pummice stone is next
used to remove the cuts of the former then two more stones are substituted which
are still finer than previous ones the surface is thus gradually reduced fine enough
and smooth enough for the engravers tool.
Now my invention is designed to prepare these plates for the engraver by
machinery and dispense with the laborious manual labour above described. It
consists of a machine with a certain number of frames in which the copper or
other plates to be ground are held while operated upon by successive stones and
burnishers These frames are of various sizes to suit the sizes of plates to be
ground and they and the stones or burnishers while travelling at different speeds
have a horizontal reciprocating motion, the motion of one being in a direction
at about right angles to the direction of the motion of the other
Referring to the drawings
•
Fig 3-Sectional elevation on line α x
Fig 4 Sectional elevation on line y-y
In these A are the frames which hold the plates to be ground, They are shown
of various sizes to suit different sizes of plates. B, gantree upon which they slide.
One long shaft C carrying a screw C¹ for each frame runs the entire length of the
machine. The screws C₁ attached to the frames by nuts c cast or fixed to each
gives them all a horizontal reciprocating motion.
The pitch of each screw C¹ is so proportioned to the width of the frame to
which it is attached that the frames will all complete their travel in one direction
together and thus each stone or burnisher (F¹) will reach the edge of the plate at
the same time each frame travelling a distance equal to the width of the plate it
carries.
D. is a rocking shaft carrying a series of arms E These arms are adjustable in
length and are linked to the stone carriers or rubbers F with a hinged joint G.
The shaft D gives to the stone carrier a much quicker transverse horizontal travel
than the frames A receive from the screw shaft C
The telescopic arms E in the slides shown at E' regulate the length of the travel
of the stones or burnishers which are weighted with suitable weights H The
plates are held in each frame centrally by two clamping bars a bevelled to fit the
edges of the plates which are worked by a right and left hand screw I operated
by a handle at I¹
The long screw C is revolved by means of two ratchet wheels J. K. one for the
right and the other for the left hand motions. These are operated by a ratchet

page_text: .
lever placed between them which is provided with two spring catches one for each
wheel, one only of which can be in action at a time. These ratchets carry the
wheel round by the teeth one sixth at a time giving the frames A a very slow
motion. The selfacting reversing arrangement is gained by a link and weighted
lever L travelling on a. screw M of the same pitch and length as that attached to
the narrowest frame and corresponding exactly with the travel threads of the
screws actuating the other frame. The link L¹ presses on the cranked lever N
which keeps the ratchet lever (by means of a finger O) at work against one wheel
When the lever L arrives at either end of the thread of the screw M it is caught
by a projecting peg P which throws it over the centre carrying the link L' with it,
which then bears on the opposite side of cranked lever N and so changes the action
of ratchet lever from one wheel to the other reversing the screw shaft C instantly.
Water is supplied to each frame in a small stream or succession of drops by
means of a pipe R. from a cistern placed at the top of the machine or in any
convenient position The frames A slope from front to back allowing the water to
run into a long trough T at their lower ends
The mode of operation is very simple the plates to be prepared for engraving
upon are placed in the frames A and held firmly in position therein by the
clamps a screwed tightly against them The machine is then set in motion and
the stones or burnishers are caused by the motion of the rocking shaft D to move
to and fro across the surface of the plate while the motion of the screw C carries
the plates horizontally from side to side The water necessary for the grinding
operation is supplied from a small cistern S at the top of the machine through a
pipe R and passes off from the back of the frames carrying with it the refuse from
the grinding
Having now described my invention and the best mode known to me of
carrying it into effect I wish it to be understood that what I believe to be new
and desire to protect under the hereinbefore in part recited Letters Patent is
1st The manufacture of apparatus applicable for grinding or preparing the
surface of plates for engraving on in which the plates are operated upon by a
series of stones or burnishers caused to pass to and fro over their surfaco while at
the same time the plates receive a horizontal reciprocating motion in a direction
at right angles to that of the grinders substantially as described and shown..
2nd A machine applicable for grinding or preparing the surface of plates for
engraving upon in which the stones or burnishers with adjustable travel receive a
reciprocating motion from a rocking shaft and the frames which carry the plates
are moved to and fro longitudinally in a direction at right angles to that of the
grinders by means of a long screw or series of screw threads of a regulated pitch
on a. shaft which give to each frame a travel of the length of itself in the same
time or the mechanical equivalent of such screw substantially as described.
3rd The machinery applicable for grinding and bringing to an even surface
copper plates used in pottery engraving constructed and arranged substantially as
herein described and shown.
İn witness whereof I the said Thomas Smith have hereunto set my hand
and seal this 24th day of July in the year of our Lord one thousand eight
hundred and eighty two