HAND GRINDING APPARATUS FOR LITHOGRAPHIC STONES
Year: 1886

page_text: I, RICHARD KOCH Manufacturer of Cottbus in the Kingdom of Prussia and
German Empire, do hereby declare the nature of my said invention for "HAND
GRINDING APPARATUS FOR LITHOGRAPHIC STONES" and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :—
The method hitherto in use of grinding lithographic stones by hand (and by
means of a so-called rubber) requires both skill and practice and a great amount
of strength on the part of the workman, and in spite of that unevennesses are
frequently found in the stones, which makes the printing on them all the more
difficult.
All drawbacks of this nature are avoided by the compendious grinding apparatus
illustrated in the accompanying drawing. It excels both in simplicity and cheap-
ness; no great exercise or strength is required to work with it.
.
Fig. 1) represents a side-view of the apparatus together with a longitudinal
section in part,
'
2) is a front view with a cross-cut in part,
"
»
3) is a plan of the upper bearing-plate, and
27
4) shows a plan of the grinding plate.
Two beams a a which have to bear the whole apparatus and at the same time to
resist the counter-pressure caused by the grinding are fastened to the ceiling of the
laboratory. On the underside of the beams are fastened the flat iron rails b b and
to these the rails c c are secured in such a way that an intermediate space is left
between the upper rail b and the under rail c. In this space two rollers d d can
move freely. These rollers d d are fastened to the bearing-plate T of the apparatus
in such a way that they can revolve. Plate T is provided with 5 openings
symetrically applied in which the spindles ƒ and g g 9 g can rotate with little play
but cannot get displaced. Below the bearing-plate T the spindle f has a cog-
wheel h and a handle i. The spindles g are likewise provided below the bearing-
plate T each with a cog-wheel k, which all gear into the cog-wheel h of spindle f.
These spindles g have on their lower ends a square threaded screw by means of
which they bear the grinding-plate S. The latter being provided for this purpose
with projecting nipples having female threads. Spindles g and their screws are
made long enough to allow the plate S a vertical motion. When the handle i is
°

page_text: turned the rotating motion is transferred by cog-wheel h to cog-wheels k, which
are equally large and to spindles g by means of which the grinding-plate S is raised
or lowered, or pressed less or more against the stone L to be ground. The grinding
of the stone is carried out by pulling the grinding-plate S backward and forward.
For this purpose plate S is provided with handles m. Meanwhile the rollers d
press against the upper rails b and run along them. All that is to be done by the
workman is to move the plate S backwards and forwards; the necessary pressure
is produced by the weight of the apparatus and by the driving of the screw-
spindles g.
Grinding-plate S is made of chilled cast-iron or any other suitable material. In
this manner the stone is ground perfectly even without its being necessary to use
expensive machines or to exercise any great amount of strength.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
A hand-grinding apparatus for lithographic stones in which the grinding is
performed by moving backwards or forwards a grinding-plate S, made of chilled
cast-iron or of any other suitable material and suspended to four screw-spindles
and which can be raised or lowered by means of handle i, spindle f, cog-wheels h
and k, and in which the backward and forward motion of the apparatus is rendered
possible by using rollers d which are fastened to the bearing-plate T and run
between the rails b and c secured to the beams a a.
HUGHES, ELI & HUGHES,
Agents for the Applicant.