IMPROVEMENTS IN AND IN MACHINERY FOR MAKING SLABS OF PLASTER OR COMPOSITION FOR CEILINGS AND OTHER PURPOSES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Richard William Hitchins at the
Office of the Commissioners of Patents on the 13th June 1882.
RICHARD WILLIAM HITCHINS of Stoke Newington in the County of Middlesex
"IMPROVEMENTS IN AND IN MACHINERY FOR MAKING SLABS OF PLASTER OR
COMPOSITION FOR CEILINGS AND OTHER PURPOSES
"
My Invention relates to the manufacture of compound slabs of plaster cement or
composition cast or moulded upon coarse canvas known as scrim or upon wire
netting or other suitable open fabric which slabs are intended to be employed as a
foundation for ceilings, linings for walls and other surfaces or for the ceilings and
linings themselves and for "pugging" purposes, and it consists first in a mode of
manufacturing such slabs in long lengths by machinery instead of in small slabs
by hand as hitherto practised by me and as described in the specification of former
Letters Patent granted to me and dated 4th May 1875, No 1665, and consists
secondly in the machinery employed in such manufacture. The construction and
operation of the machine are as follows, from which the method of manufacture will
be readily understood.
The machine consists of a longitudinally traversing mould, table or bed mounted
to travel on ways upon a suitable frame and beneath a pair of horizontal mixing
drums supplied with the plaster cement or composition and discharging the same
in an even stream over the whole breadth of the mould table, the fabric to be
embedded in the plaster or other slab being drawn from a reel and passed through
the machine in such manner that the liquid plaster or composition is deposited
from the one mixing drum beneath, and from the other drum above, the fabric so as
to be applied upon both sides thereof. Instead a mould table traversing to and
fro I prefer to employ an endless chain of moulds supported on a table travelling
always in one direction and these moulds may be made upon an endless fabric of
coarse wire cloth which would permit the ready escape of superfluous water and at
same time form a key on the surface of the slab for the final coat of plaster to be
subsequently applied when the slabs have been fixed in position.
The moulds have raised ledges or flanges at the sides bevelled or otherwise
formed to produce the desired bevel or configuration of the edges of the alab, and
suitable adjustable gauges, scrapers, or rollers are mounted above the mould table to

page_text: bring the cast slab to a uniform thickness the rollers being engraved or otherwise
formed with the counterpart of any pattern it may be desired to produce upon the
Blab.
The mixing drums are supplied with plaster or other composition from hoppers
above and they are furnished with rotary shafts having blades like those of a pug
mill. The plaster or composition is discharged from a longitudinal orifice at the
lower side of each drum and suitable guides may be provided for conveying it to
the proper point of desposit if necessary.
In case it is desired to embed laths of wood in the slabs, as described in my former
Patent before referred to these, may be fed in by means of rollers at the time of
casting or moulding the slab.
With the machine above described I may combine a guillotine knife operated
mechanically or otherwise for cutting the slabs to the lengths required.