Improvements in Holding and Adjusting Circular Cutters for Lathes and like Machines.
Year: 1898

page_text: Date of Application, 18th Feb., 1898
Complete Specification Left, 15th Nov., 1893—Accepted, 7th Jan., 1899
PROVISIONAL SPECIFICATION.
Improvements in Holding and Adjusting Circular Cutters for Lathes
and like Machines.
We, THE HOFFMANN MANUFACTURING COMPANY, LIMITED, and ERNST GUSTAV
HOFFMANN, Engineer, both of 43, Beech Street, Barbican, London, E.C., do hereby
declare the nature of this invention to be as follows:-
This invention relates to means for holding and adjusting circular cutters
having a cutting edge adapted to be presented to a rotating body to cut or shape
same as in a lathe, the invention being however particularly applicable for use in
connection with an automatic ball making machine in which small balls or like
articles are turned from a rotating wire:
Considerable difficulty has heretofore been experienced in the holding and
adjusting of circular cutters and the present invention is designed to overcome
the same.
In carrying out the invention the circular cutter is attached to a bar or mandril
which seats in a recess or jaw of the slide. In a recess at right angles to this
in said slide is located a clamp one end of which is slit and adapted to embrace
the bar or mandril of the cutter. A screw is provided for tightening the clamp
upon said mandrel and a pin carrying an eccentric thereon passes through the
clamp and the sides of the slide. Said pin is provided with a handle so that on
turning same the eccentric draws the clamp tightly onto the mandrel and holds
it in the recess or jaw of the slide.
As the adjustment of the cutters edge is in a circular direction, as the cutter is
ground off the position of the clamp must be gradually altered so as to have the
cutters edge held always in the required position. A screw is provided at the
rear of the clamp which passes through same and bears on a part of the slide the
adjustment of this screw moving the cutter on its axis.
As explained the clamp is held in the slide by an eccentric pin which draws the
mandril of the cutter into its seat. In consequence however of the changing
positions of the clamp resulting from the continuous grinding of the cutter it
is not feasible to have a fixed point where the eccentric will in all cases bear
upon the clamp.
To provide means therefore against which the eccentric may efficiently act no
matter what the position of the clamp a block is provided in the clamp having a
face formed as a segment of a circle the centre of which is the axis of the cutter
and against this face the eccentric bears. A screw adjustment is preferably pro-
vided for the block to be adjusted vertically a wedge at the back of same provid-
ing means for adjusting the position of the block laterally to adjust the pressure
of the eccentric.
To adjust the cutter itself laterally its mandril or bar may carry inside same a
rod having a pin projecting from same and passing through the mandril into.a
circular groove formed inside a part of the clamp. The end of the rod is screw

page_text: threaded and carries a nut suitably held to the mandril and preferably provided
with micrometer divisions to enable same to be readily adjusted.
When the nut is turned the rod (through the pin which engages with the
groove in the clamp) is capable of moving the mandril laterally in said clamp the
tightening screw of same having been previously loosened.
Dated the 18th day of February 1898
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London, Chartered Patent Agent,
Agent for the Applicants.
Improvements in Holding and Adjusting Circular Cutters for Lathes
and like Machines.
We, THE HOFFMANN MANUFACTURING COMPANY, LIMITED, and ERNST GUSTAV
HOFFMANN, Engineer, both formerly of 43, Beech Street, Barbican, London, but
now of Chelmsford, Essex, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:.
This invention relates to means for holding and adjusting circular cutters
having a cutting edge adapted to be presented to a rotating body to cut or shape
same as in a lathe the invention being however particularly applicable for use in
connection with an automatic ball making machine in which small balls or like
articles are turned from a rotating wire."
While the employment of circular cutters has long been recognised as a great
advantage, their general use, has in many cases, been delayed or altogether pre-
vented on account of the difficulty experienced in securing them in a substantial
and practical manner in the slide rest of the machine, and because the adjustment
of the cutters in relation to the work it is acting upon offers great obstacles.
In machines, such as the ball making machine referred to, an additional
difficulty is experienced in so mounting the cutter upon the slide rest that the
screws or eccentrics used to fasten it upon the rest should not in any way strain
or spring the casting composing the rest.
Inasmuch as the machine has to work so accurately it is most important that
its slide rest may move freely and at the same time without any play, and since
the slightest straining of the slide would interfere seriously with its free move-
ment, it is of the greatest importance that the means for securing the cutter upon
the slide be of such a construction that they do not in the slightest degree cause
straining or springing of the slide.
In the accompanying drawings:
Fig. 1 is a plan of a slide rest and a circular cutter constructed according to
this invention.
Fig. 2 is an end view.
Fig. 3 is a longitudinal section through a part of the mandril to which the
cutter is attached.
Fig. 4 is a section on line, Fig. 1, and
Fig. 5 is a section on line y-y of same figure.
The cutter a is shown as adapted for making rivets out of a rotating wire but
its shape is immaterial to the present invention. It is secured to and carried by
a mandril b, and a clamp or holder e in position in a slide d. The cutter is
secured upon its mandril by a nut b¹ and the mandril beds or rests in semi-
..circular grooves e formed in the ends of projections d' of the slide d. and is

page_text: drawn tight in said grooves by means of the lever shaped handle or clamp c
and an eccentric pin f which passes through holes in the projections d¹ d' and
through a larger hole in the clamp which is situated between said projections.
The pin has a part f' which is eccentric to the rest of the body of the pin and the
holes in the projections dd, and this part occupies a position in the hole through
the clamp c.
The clamp c is split at Fig. 5 and a screw g passes through it at
this point to tighten the clamp upon the mandril b. The clamp also has a
screw passing through it at the end and bearing on a hardened block in
slide d, a wedge block k having a curved surface for the eccentric f to bear
against screws for adjusting same and a wedge block at the rear of block k
for altering the position of same laterally. The adjustment of the cutters edge
in a vertical direction, or rather in a circular direction around its own centre, is
effected after first loosening eccentric pin f by screw the clamp being raised at
the handle and by turning the screw into same. When the limit of adjustment
is reached by reason of the number of times the cutter has been ground it is
necessary to change the position of the cutter in clamp c so as to permit the
screw to be almost entirely withdrawn and the clamp c to be brought down again
as close upon the slide d as possible.
One of the objects of this construction is to obviate the readjustment of the
cutter in its clamp e as little as possible, because such adjustment is always more
or less interfering with the accurate setting of the cutter, and it is for this
reason that it is desirable to be able to grind off the cutter a good deal before it is
really necessary to reset it in position in connection with the clamp c.
Assuming that the clamp is at its highest point and that the position must be
changed, all that is necessary to effect the change is to loosen screw g withdraw
screw and then force the clamp down upon the slide while rotating the
mandril 6 within the clamp c to the required extent. As soon as this is accom-
plished screw g is again fastened and the fine adjustment is effected by the
screw h.
As already explained the lever shaped clamp c is fastened to the slide by the
eccentric f which draws the mandril against its semi-circular seats on the slide.
In consequence of the changing position of the clamp c resulting from the con-
tinuous grinding of the cutter, it is impossible to have a fixed point where the
eccentric would in all cases bear upon the clamp c.
In order to provide therefore means against which the eccentric f' could
bear, no matter what the position of clamp c, the arrangement of wedges 1, k,
is employed.
The curve of wedge coincides with the curve of a circle, the radius of which
starts from the centre of the cutter and terminates at the point against which
the eccentric f¹ bears. In order to make this wedge & fall absolutely in line with
the true centre of the just mentioned circle, it is provided with the two screws k¹, k²,
whereby it can be adjusted lower or higher, as required. Said wedge k having
the just described curved face, and it being further provided with means for
adjusting in a vertical direction makes it clear that the eccentric will always
find a properly adjusted point against which it can bear, no matter where the
clamp c is positioned. In order to provide for inaccuracy in workmanship on the
one hand, and for wear and tear upon the points of contact between the eccentric f¹
and wedge on the other hand, the wedge has been provided. Said wedge
has a screw on one side only, by means of which it is possible to move wedge k
away from, or to the centre of the cutter, thereby permitting eccentric fi to
draw the clamp c to the slide with more or less pressure.
In order to overcome the straining or springing of the slide when fastening
the cutter upon it, as before explained it will be noticed that the strains created
by fastening the clamp c are only located as between the metal itself.
The mandril b is drawn upon its semi-circular seat provided upon the two
extensions of the slide, and the eccentric f is forced in a direction towards the

page_text: seats of said mandril, and therefore no matter what the strain between these
two points, the slide generally, or any other part of the slide, is not affected
thereby.
The arrangement offers great facility in taking out the cutter, grinding it,
and putting it back in exactly the same position it occupied before, and for this
purpose the eccentric pin f is withdrawn and the clamp and cutter lifted out and
ground without altering the position of the cutter in said clamp. All that is
necessary afterwards to compensate for the amount which has been ground off
at is done by screwing in the screw h.
For very accurate work, it is important to be able to accurately adjust the cutter
laterally or longitudinally to the wire or material it works upon, and in order
to effect such accurate adjustment quickly and without complication the device
shown at Fig. 3 is employed.
The principal part of Fig. 3 is the body of the mandril b through which a hole 62 is
drilled in line with its axis. Within the said hole is a pin s having on one end a screw
threads and on the other a hole through which a smaller pin m passes at right
angles. The ends of the pin s fits into a nut r said nut being secured partly
within the mandril bin such a manner that it cannot move one way or another
longitudinally, which is effected by a pin engaging in a groove in nut r
and passing through mandril 6 at right angles to its axis.
The pin m which passes through the other end of pin sengages internally
with clamp c for which purpose a groove is provided in said clamp, extending
all round the internal surface. This is seen best at Fig. 5 which also shows how
the pin m can lie inserted through a small hole provided on top of the clamp c.
There is a still smaller hole at the bottom of clamp c.
The larger
hole is for the insertion of the pin m and the smaller hole is for the
purpose of pushing out pin `m but at the same time preventing it from falling
through which it otherwise would do.
The mandril bis furthermore provided with a slot t shown also in Fig. 1
wherein pin m can be moved longitudinally, to a limited extent.
Coming now to the description of the action of these parts, it will be noticed
to start with that the mandril b can turn within clamp e without obstacle because
the pin m will travel around the internal groove in clamp e but if nut r be
rotated one way or another it will force the mandril and its cutter by means of
a pin m laterally and since the nut engages with pins by means of a very
fine thread and the nut being furthermore divided on its periphery with a
number of divisions which will produce in combination with the screw thread a
direct reading of say 1/1000th of an inch, it follows that the lateral movement of
the cutter mandril within the clamp c can be determined by means of said micro-
meter nut to a very fine degree.
Of course when said adjustment is used it is necessary to loosen screw 9 as
much as is necessary, to permit the mandril to move in the clamp. The cutter
with its mandril can be removed entirely from clamp e very quickly by simply
withdrawing pin m through the hole on the top of clamp c when said mandril
is free to be taken out of the clamp.
C
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. For holding a circular cutter the combination with a rotatable mandril
carrying the cutter, of a clamp embracing said mandril, means for tightening
the clamp and holding the mandril in any desired position and
for holding the clamp and for moving it together with the cutter
around the axial line of the latter, 'substantially as described.
means
2. For holding a circular cutter, a clamp having a movement together with
and around the axis of same, a slide rest for holding the clamp an eccentric for
holding the clamp in the rest and a block having a curved face corresponding to
the curve of a circle, the centre of which is the centre of the cutter and against

page_text: which the eccentric can bear at any position of the clamp, substantially as
described.
3. For holding a circular cutter a movable clamp, a wedge block having a
curved face corresponding to the curve of a circle the centre, of which is the
centre of the cutter, an eccentric forming part of a device for holding the clamp,
adapted to bear against the curved face of the wedge block, and means for
adjusting the wedge block both horizontally and vertically, substantially as
described.
4. For holding a circular cutter, a mandril carrying the cutter, a clamp in
which the mandril is held, and in which it may be turned, a pin located in a hole
in said mandril, a second pin carried by the first, a slot in the mandril through
which same passes a groove in the clamp in which the pin engages, means for
moving the pins in the mandril so that the latter is moved longitudinally in the
clamp for the purpose of adjustment and means for withdrawing one of the
pins to allow the mandril to be released from the clamp, substantially as
described.
Dated this 15th day of November 1898.
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London,
Chartered Patent Agent for the Applicants.