Improvements in Helical Cutters or Knives for Cropping, Clipping, Shearing, and Mowing Machines and the like.
Year: 1892

page_text: Date of Application, 29th Aug., 1892
Complete Specification Left; 23rd May, 1893-Accepted, 24th June, 1893
PROVISIONAL SPECIFICATION.
Improvements in Helical Cutters or Knives for Cropping, Clipping,
Shearing, and Mowing Machines and the like.
I, ROBERT FULTON CRAIG, of Caledonia Engine Works, Paisley, in the
County of Renfrew, North Britain, Engineer, do hereby declare the nature of this
invention to be as follows, that is to say :-
My said invention has for its object to render helical or spiral cutters or knives
used in various machines including machines for operating on woven fabrics and
grass cutting machines, more durable than as hitherto made and such as to require
less frequent sharpening or grinding.
In carrying out my invention I prefer to make the helical cutter blade of what
is known as the " bayonet" section; my improvements are however applicable
with various sectional shapes. I make the back or part of the blade by which it
is fixed to the roller or centre on which it is mounted, of wrought iron, and I make
the wrought iron extend to the extreme cutting edge on the convex side but on the
concave side plate the blade with steel the steel extending from the extreme edge
inwards to a suitable distance.
With this construction a very hard steel can be used without the same liability
to break or crack which there is when the edge and part near it is entirely of steel;
whilst in the event of a crack occurring the wrought iron tends to prevent the
damage from spreading and to retain pieces which might otherwise fly off. The
wrought iron is on the side on which most wear occurs and consequently the
sharpness of the extreme steel edge is longer maintained that in such cutters as
hitherto made.
Dated this Twenty-seventh day of August 1892
EDMUND HUNT,
Applicant's Agent.
COMPLETE SPECIFICATION.
Improvements in Helical Cutters or Knives for Cropping, Clipping,
Shearing, and Mowing Machines and the like.
1, ROBERT FULTON CRAIG, of Caledonia Engine Works, Paisley, in the
County of Renfrew, North Britain, Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My said invention has for its object to render helical or spiral cutters or knives
used in various machines including machines for operating on woven fabrics and
grass cutting machines, more durable than as hitherto made, and such as to require
less frequent sharpening or grinding.
In carrying out my invention I prefer to make the helical cutter blade of what is
known as the " bayonet" section, my improvements are however applicable with
various sectional shapes. make the back or part of the blade by which it is fixed
to the roller or centre on which it is mounted, of wrought iron, and I make the
wrought iron extend to the extreme cutting edge on the convex or following side
but on the concave or cutting side I plate the blade with steel extending from the
extreme edge inwards to a suitable distance.
And in order that my said invention and the manner of performing the same
may be properly understood I hereunto append a sheet of explanatory drawings,

page_text: to be hereinafter referred to, and showing parts of helical cutters or knives as
made with my improvements.
Figures, 1, 2, and, 3, are transverse sections of 'parts of three examples of my
improved helical cutters or knives. In these drawings the same reference letters
are used to mark the same or like parts wherever they are repeated.
As shown in Figure, 1, of the drawings I make the back or part of the blade, A,
by which it is fixed to the centre, or roller, B. (indicated by dotted lines) on which
it is mounted, of wrought iron, C, and I make the wrought iron extend to the outer
edge, D, on the convex side, but on the concave side I plate the blade with steel, E,
preferably in the proportion of one part of steel to two parts of iron, the steel,
which in the figures is indicated by reversed section lines extending from the
extreme edge inwards to a suitable distance.
Figures, 2, and, 3, show parts of other forms of blades, A, their front parts
being similarly plated or faced with steel, E, extending from the extreme edge, D,
inwards.
With this construction a very hard steel can be used without the same liability
to break or crack which there is when the edge and part near it is entirely of
steel; whilst in the event of a crack occurring the wrought iron tends to prevent
the damage from spreading and to retain pieces which might otherwise fly off.
The wrought iron is on the side on which most wear occurs and consequently the
sharpness of the extreme steel edge is longer maintained than in such cutters as
hitherto made.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
The improvement in helical cutters or knives consisting in forming the back and
part of the blades of wrought iron which wrought iron extends to the extreme outer
edge of the blades and is plated with steel on one side substantially in the manner
and for the purposes hereinbefore described.
Dated this Twenty-second day of May 1893.
EDMUND HUNT,
Applicant's Agent.