Improvements in Rotary Cutter Heads.
Year: 1891

page_text: Date of Application, 6th July, 1891
Complete Specification Left, 6th May, 1892-Accepted, 6th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements in Rotary Cutter Heads.
I, CHARLES LOUIS GOEHRING, of Alleghany, United States of America, at
present residing at the Cannon Street Hotel, Cannon Street, in the City of London
do hereby declare the nature of this invention to be as follows:-
Hitherto it has been the practice is securing these rotary cutter heads to the
shafts which operate them to fasten them by means of, a pinching screw or an end
nut which jamb them against a collar or equivalent upon the shaft; I have however
found by experience that both these methods are faulty inasmuch as however
slightly the cutter heads appear to be invariably out of truth when running. This
is sometimes more- and sometimes less the case but the fact appears to be that
either the shaft is bent or the nut bears harder upon one side of the head than upon
the other; whatever the exact cause the result is the same that the head does
not run true. To obviate this I have adopted with complete success the following
plan
The invention may be applied to any ordinary description of rotary cutter head
and consists in elongating the head so as to provide at each end a length of tube
which is screw threaded on the outside and tapered and provided with any required
number, say for example six longitudinal saw cuts, after the manner of a well-
known form of drill chuck. Upon this tapered portion screws a nut either tapered
internally or not by which the split tube is compressed radially upon the shaft to
which the cutter head is thus concentrically secured at each end. The cutter head
being truly bored and turned can be made to fit the shaft which by this arrange-
ment has no tendency to bend with perfect mechanical accuracy, the result obtained.
being altogether superior to anything of the kind that has ever before come under
my notice.
The interior of the cutter head may be recessed so as to be slightly larger than
the diameter of the shaft while the bore of the split ends may with advantage be
made as nearly as practicable to coincide with the diameter of the shaft by which
means very great mechanical accuracy can be easily obtained.
These cutter heads are particularly suitable for use in wood working machinery
but are otherwise applicable.
Dated this 6th day of July 1891
W. P. THOMPSON & BOUlt,
Agents for the Applicant.
"
COMPLETE SPECIFICATION.
Improvements in Rotary Cutter Heads.
I CHARLES LOUIS GOEHRING of Alleghany, United States of America, at
present residing at the Cannon Street Hotel, Cannon Street, in the City of London,
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.:―
Hitherto it has been the practice in securing cutter heads to the shafts which
operate them to fasten them by means of a pinching screw or an end nut which
jam them against a collar or equivalent upon the shaft; I have however found
by experience that both these methods are faulty more particularly at high speeds
inasmuch as, however slightly, the cutter heads appear to be invariably out of
truth when running. This is sometimes more and sometimes. less the case but the
ID 71

page_text: fact appears to be that either the shaft is bent or the nut bears harder upon one
side of the head than upon the other; whatever the exact cause the result is the
same that the head does. not run true.. To obviate this I have adopted the
following plan with such success that I am able to run the heads with perfect
practical accuracy 50% faster than with the old method of fixing.
The invention may be applied to any ordinary description of rotary cutter head
and consists in elongating the head so as to provide at each end a length of tube
which is screw threaded on the outside and tapered and provided with any required
number, say for example six longitudinal saw cuts, after the manner of a well
known form of drill chuck. Upon this tapered portion screws a nut either tapered
internally or not by which the split tube is compressed radially upon the shaft to
which the cutter head is thus concentrically secured at each end. The cutter
head being truly bored and turned can be made to fit the shaft (which by this
arrangement has no tendency to bend) with perfect mechanical accuracy, the
result obtained being altogether superior to anything of the kind that has ever
before come under my notice.
The interior of the cutter head may be recessed so as to be slightly larger
than the diameter of the shaft while the bore of the split ends may with advantage
be made as nearly as practicable to coincide with the diameter of the shaft by
which means very great mechanical accuracy can be easily obtained.
These cutter heads are particularly suitable for use in wood working machinery
but are otherwise applicable.
In the accompanying drawings
Figure 1 is a view of an ordinary cutter head but with the improved fastening.
Figure 2 is a longitudinal section of the same cutter head on the line 2-2 of
Figure 2, with the shaft in elevation.
Figure 3 is an end view of the same and
Figure 4 is a view showing special means for positively securing the cutter
head upon the shaft, this form being as a rule only required in the case of large
heads.
Like letters represent like parts throughout the drawings.
A is the shaft and B the cutter head upon which the cutters C may be secured
in any desired manner. The method shown in the drawings is one commonly
adopted and consists of headed bolts D fitting into T-slots in the cutter head and
passing through the cutters outside which nuts D¹ are screwed upon the bolts D, thus
fixing the cutters in position. This fastening is merely introduced here so as to
show a complete cutter head as the particular shape or construction of the head
and the manner of fastening the cutters are outside the present invention.
The head B is extended at one or both ends according to circumstances as at E
forming a projecting, tube or nipple which is split or provided with any required
number (in the drawing six are shown) of saw cuts E' so as to impart to the tube
the necessary spring. The outside of the nipple E is screw-threaded as shown and
a nut F which may if desired be tapered to correspond with the taper of E is
screwed upon it so that as will be well understood the separated portions of E will,
as the nut is screwed further upon the Dipple, be caused to grip the shaft A and
thus hold the cutter head firmly upon it. In the lower part of Figure 2 the
head B is shown recessed at A¹.
Usually it is desirable to secure the cutter head by both ends as shown in
Figures 1 and 2, but as the bore of the head and the shaft may be tapered it is
not always necessary to secure it with the screw and nut at both ends.
In some cases, and particularly in the case of large and long heads it is necessary
to have some positive means of preventing any slip between the cutter head and
the shaft although as a rule, and particularly for small heads the method shown in
Figures 1 and 2 of the drawings is ample, and found to work excellently in practice.
Various means may be employed for this purpose, the plan illustrated in Figures 2
and 4 of the drawings being a practicable one. In this case G is a collar or clutch
secured in any convenient manner upon or being part of the shaft A. and provided

page_text: with alternate projecting and receding portions G and G' and to engage with this
clutch the nipple E is correspondingly provided with projecting portions E which
enter the recess G the whole forming a complete clutch and making a positive
connection between A and B. With this form of clutch and six saw cuts E' it is
desirable that the portions of E cut away should apply in each case to two
contiguous parts so that the portion E² may be a solid portion without any cut E' in
it as otherwise a certain amount of spring or give might result. The clutch here
described is a useful one and very convenient where the cutter is placed upon the
shaft remote from any enlargement or end thereof, but it will be readily seen that
the precise form of the positive connection between A and B may be greatly varied
without departing from the spirit of the invention.
The nipples E are described as being tapered and the nuts tapered to correspond
or not as required, but if desired the nipples may be made parallel and tapered nuts
run upon them. The former arrangement is however preferred.
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 :-
1. As a means of securing a cutter head upon its shaft the combination with the
cutter head of one or more externally threaded split extensions such as E E and
nuts F substantially as and for the purpose described and illustrated in the
accompanying drawings.
2. The combination with a shaft A of a cutter head B and one or more externally
threaded split extensions such as E E and nuts F substantially as and for the
purpose described and illustrated in the accompanying drawings.
3. The combination with a cutter head and shatt of a clutch such as G G¹ G'
and E E E F substantially as described and illustrated in the accompanying
drawings.
Dated this 5th day of May 1892