A New or Improved Process for Sharpening Files.
Year: 1891

page_text: Date of Application, 11th Aug., 1891-Accepted, 12th Sept., 1891
COMPLETE SPECIFICATION.
A New or Improved Process for Sharpening Files.
I JULIUS ERLENWEIN of Edenkoben, Rhenish Bavaria, File Merchant 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:-
This invention relates to sharpening files by means of which the hitherto costly
method of sharpening by means of sand blast or jet is replaced.
This new method or process consists in operating upon the teeth or serrations of
a file with a rapidly rotating cylindrical brush the wire bristles of which are
arranged obliquely upon the axis of the brush frame emery sand and the like being
used in conjunction therewith.
A. brush of this kind is shown in the accompanying drawings in which Figure 1
is a plan and Figure 2 a longitudinal section of part of a file in the process of being
acted upon with a wire brush.
a Figure 2 is the cylindrical brush frame turning upon the axis the cylindrical
body of the brush is furnished with oblique perforations e in which are inserted
the bristles of steel, iron, brass wires or the like in such a manner as to have a
direction corresponding to the obliquity of the teeth d of the file e held parallely
to the axis of the cylindrical brush frame a.
The brush above described is used as follows:-It is mounted in a suitable frame
fitted to suitable driving gear and set thereby in motion-emery sand or the like
being supplied while the file requiring to be sharpened is pressed against the wire
bristles in the manner shown in Figure 2 until the teeth of the said file are
sufficiently sharpened. By this manner of proceeding each tooth of the file is
separately sharpened in the same manner as a knife an axe a chisel a scythe and
the like may be sharpened by means of a steel or of a stone. The files thus
sharpened are moreover polished to a certain extent and are thereby rendered con-
siderably harder than is effected when they are treated by means of a sand blast
or jet. The consequence is that the files sharpened according to this invention
have better cutting edges and a greater ductility than could be obtained heretofore
and hence cannot be so readily clogged so that on this ground alone they are
distinguished by their greater working efficiency.
As regards the re-sharpening or re-setting of files which have become blunt a
great advantage is obtained by this process which is made obviously clear by
referring to Figures 3 and 4 of the accompanying drawings. Figure 3 shows the
teeth of a re-sharpened file while Figure 4 shows a file sharpened according to
this invention. The sharpened teeth carry at their upper edge a bent back burr f
which deviates considerably from the form of a cutting edge suitable for working
on metals. This burr cannot be prevented when re-setting a file as heretofore being
a consequence of a lateral over pressure in the material through the various cuts
which are set close to one another. The teeth g sharpened according to my process
(Figure 4) have on the contrary a clear cutting edge.
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 :
A process for sharpening files consisting in subjecting the latter to the treatment
with the addition of sand and the like-of a cylindrical brush the bristles c of
which have a corresponding slant direction with that of the teeth of the file this

page_text: brush being made to revolve rapidly substantially as shown and described in the
drawings.
Dated this 11th day of August 1891.
TONGUE & BIRKBECK,
34, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Patentee.