Improvements in Dental Burrs, and in Hand-pieces therefor.
Year: 1895

page_text: Date of Application, 5th Feb., 1895-Accepted, 5th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in Dental Burrs, and in Hand-pieces therefor.
1, JOHN DIETRICH WILKENS, of No. 2231 Prairie Avenue Chicago, in the
County of Cook and State of Illinois, United States of America, Mechanical
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 invention relates to certain improvements in hand pieces and burrs for dental
engines; and it consists in certain features of construction of those parts of the hand
piece which are manipulated to lock and release the tool; and in certain features of
construction of the tool, i.e., a dental burr.
In the accompanying drawing,
Figure 1 is a view of the hand piece complete.
Figure 2 is a sectional view, partly in elevation, showing the tool in position to
be withdrawn.
Figure 3 is a view showing separately and detached the chuck, the chuck actuating
rod and the rear section of a divided spindle.
Figure 4 is a perspective view, partly broken away, of the forward section of the
divided spindle.
Figure 5 is a perspective view of a cam lever.
Figure 6 is a similar view of an actuating collar for the cam lever.
Figure 7 is a sectional elevation of the connected ends of the spindle sections
and the sliding collar for actuating the cam lever, the latter showing in side
elevation.
Figure 8 is a detail plan view of the outside casing.
Figure 9 is a similar view of a sliding sleeve which works over the casing.
Figure 10 shown in inverted plan and side elevation, respectively, a removable
detent used in connection with the sliding sleeve.
Figure 11 is a perspective view of an eight toothed burr, showing the stem
partially broken away.
Figure 12 is an end view of the head or working end of the burr shown in
Figure 11.
Figure 13 shows a six toothed burr; and
Figure 14 a twelve toothed burr, both of which embody my invention.
The hand piece shown in the accompanying drawings belongs to that class wherein
a tool driving spindle is revolubly mounted within a non-rotating casing or sheath,
the spindle being adapted for connection at its rear end to a flexible shaft or other
means for rotating it.
In the drawing, A represents an enclosing casing having the usual hard metal
nose piece a and an aperture a¹ in the wall of the casing toward its rear end.
Crepresents a sheath collet having threaded ends c, one of which threaded ends
engages with the internal threads of the casing A, and the other of which engages
with a coupling section (not shown). Within the collet C is an internal spindle
collet D, having a jamb nut d.
E, (Figure 3), represents the rear section of a divided spindle which has its
forward end externally threaded for engagement with the front spindle section F,
(Figure 4). The spindle section E is longitudinally slotted, as at e, Figures 2, 3
and 7, and this slot is bisected by a transverse depression e', which forms a seat for

page_text: the lugs of the cam lever G. This cam lever has a straight front face; its lower
side is curved; and the tail piece of the lever extends to about the plane of the
lugs g,
which is coincident with that of the opening of the slot e.
When the lugs g
rest in their seats, the cam lever is suspended thereby, its body resting within the
slote and the tail piece projecting into the path of travel of an internal rib h of a
collar H, which coilar encircles and slides upon the spindle section E, the rib riding
in the slot e of the spindle.
I represents a chuck operating rod which is slidably mounted in the front section F
of the divided spindle; and J represents a tubular chuck having its front end split
to provide the spring clamping jaws j. The chuck jaws are closed by their impinge-
ment upon the internal tapering walls of the front end of the spindle section. F, and
by their closing they are made to gripe the shank of a tool, as K. The collar H is
actuated by means of a sliding sleeve L, which is mounted over the aperture a¹ in
the sheath or casing A. This sliding collar has a longitudinal depression 1, the
bottom wall of which is cut away at one point . The front or end wall of the
depression is under-cut or dove-tailed, as at ". Mounted within the seat formed
by this depression is the detent M, shown in Figure 10, and consisting of a flat
plate having its forward end dove-tailed or bevelled to correspond with the under-
cut or dove-tailed front wall of the seat, as shown in the side elevation Figure 10,
at m, while the rear end of the detent is preferably cut away or notched, as shown
at m'. On the lower side of this plate M is the lug M', which projects through the
aperture and engages a groove h¹ in the collar H. A locking collar N has a
threaded engagement with the collar L and engages also the offset m³ of the detent M,
thus preventing the latter leaving its seat.
The operation of the parts will now be understood. When the several parts
are in the position shown in Figure 2, the tool K may have its shank entered
between the chuck jaws and then to lock the tool the sliding collar will be
drawn back, the lug of its detent moving correspondingly and in the same
direction the sliding collar H whose lug / will engage the tail piece of the
cam lever G, thrusting the lower front corner of the latter into engagement
with the sliding actuating rod I, which in turn moves the chuck forward within the
front section of the spindle, closing the chuck jaws and gripping the tool.
To release the tool, the sleeve is slipped forward, freeing the cam lever and the
actuating rod I and chuck J, and as soon as the pressure upon the latter is relieved
the tool may be easily withdrawn.
Many of the features of construction are intended to facilitate and economize
manufacture, while the particular construction is such that the various parts may
be readily assembled and securely held in position so as to attain certainty of
operation and prevent any undue wear or movement of the parts with relation to
each other. The principal feature of the invention, however, relates to the manner
of locking and releasing the tool. Where the operator desires a hand piece in
which the tools can be rapidly changed, the sliding sleeve furnishes the most
expeditious and least objectionable form of device for effecting the locking
and releasing of the tool; and in my construction the actuating collar and cam
lever are mounted upon and rotate with the spindle, while the sliding sleeve is
mounted upon the casing and is not rotatable. Furthermore, the sliding sleeve
is always maintained in operative position with relation to the sliding collar
which acts upon the cam lever so that no matter in what position the collar
and can lever may be they are actuated by the sliding of the external sleeve
in its groove. The detent, which forms the connection between the sliding
sleeve and the sliding collar, is removable to permit ready assembling of the
parts, and the dove-tailed connection of the detent with the seat in the sleeve,
in conjunction with the locking collar, affords efficient means for retaining
the detent in its place during operation and yet permits its ready removal or
insertion.
A hand piece constructed as above described has no parts which are subject to
much wear; but in order to compensate for any wear that may result, I provide the

page_text: spindle collet D with the milled head D' so that by screwing the collet D forward
in the sheath collet C compensation for wear is secured.
While I have shown the spindle as divided or constructed in two sections, I do
not limit my invention thereto, as it is obvious that this feature is structural only and
not of the essence of the invention.
The burr is so constructed as to provide at its apex suitable cutting edges,
preferably continuous with the cutting edges of the leaves or teeth extending over
the sides or body of the head of the tool, and alternating with teeth whose cutting
edges terminate short of the apex.
In the most common construction of these tools, there has been provide a series
of cutting blades whose cutting edges are arranged in spiral lines converging to the
axis of rotation of the tool and forming whorls circumferentially of the head. These
cutting blades usually terminate at the extremity of the heal at a point coincident
with the axis of rotation, and usually a channel or groove has been cut across
the point of the tool at right angles to its axis of rotation. This construction is
objectionable for the reason that the chips of tooth matter accumulate in such channel
or depression and thus clog the tool, create friction and impede and render more
painful the operation.
To remedy this defect it has been proposed to provide a burr-drill, as the
inventor calls it, having a single continuous cutting edge crossing the axis of
rotation of the tool, the theory of the inventor being that the presence of this
cutting edge would adapt the tool for use both as a drill and as a burr, and
render it equally adapted for cutting in the line of its axis as at right angles
thereto.
There are certain advantages and disadvantages incident to both of these carlier
forms of construction. In the first described construction, i.e., where the cutting
blades or leaves all terminate near the axial centre, there is no effective cutting edge
at such point, and therefore the channel is usually cut to provide a clearance, and
the burr or drill clogs as before described. On the other hand, this construction has
certain advantages in that the cutting edge is extended and is effective to a point
very near the axial centre of the head, so that side or lateral cutting as well as
cutting in the line of the axis is facilitated.
In the construction wherein a single cutting edge has been extended across the
axis of rotation of the drill, the side leaves or teeth have been grouped on opposite
sides of the head with the cutting edges of each terminating at a single point at
some distance from such central cutting edge. This leaves spaces between such
points and the cutting edge crossing the apex of the head which are not operated
upon by the side cutting leaves. It is desirable to space these cutting edges as near
together as practicable with due regard to clearance of the chips and tooth
matter; and my improvement consists in a burr having teeth or leaves provided
with cutting edges extending across the axis of rotation of the drill and bisecting
each other at said axis, and alternating or intermediate leaves having their
cutting edges terminating sufficiently short of the axis to provide for suitable
clearance for the material removed by cutting edges which cross the axis of
the burr.
In the tool shown in Figures 11 and 12, there are eight leaves or teeth, as they
are commonly called in the art, and the leaves o and o¹ are connected by a
single continuous cutting edge extending across the axis of rotation of the tool.
The leaves and pare similarly connected, the connecting cutting edge of
the leaves o, o' and p, p, bisecting each other at the axis of rotation.
Alternating with these are the intermediate leaves or teeth 9 of substantially
the same contour as the connected leaves or teeth, but their cutting edges
terminate short of the axial centre of the tool, thus providing for clearance, as
indicated at r.
The number of leaves or teeth vary considerably. In constructing small burrs,
frequently only six teeth are employed as shown in Figure 13, and in this case,
instead of having two pairs of leaves connected by continuous cutting edges

page_text: intersecting each other, three of the leaves have their cutting edges extended
across the end of the head while the intermediate leaves have their cutting edges
terminating short of the apex. In Figure 14 I have shown a burr having twelve
teeth six of which are connected in pairs by cutting edges crossing the apex and
alternated with disconnected teeth or leaves whose cutting edges terminate short of
the axis.
From the above description it will be seen that there is no "dead" point upon
the working end of this tool, as in the construction where the leaves are grouped
and terminate at the same point. The cutting edges which bisect each other at the
axis of rotation of the tool completely traverse all of the surface not touched by
the edges of the main body of the leaves, while the independent or disconnected
leaves o have their cutting edges extended sufficiently near to the axis of rotation
to assist materially in the cutting without liability of clogging the head of the tool
with tooth matter.
It will be seen that a leaf q is interposed between each pair of the connected leaves
and has an independent cutting edge, and this will be much more effective than that
wherein the cutting edges all terminate at or near the axis of the drill, and also
more effective than the construction wherein three or more of the side leaves are
converged to a single point and with a single cutting edge only extending across
the head of the drill.
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. In a dental hand piece, the combination with an outer casing or sheath having
a longitudinal working aperture in its wall, a rotatable hollow spindle mounted
therein and having a longitudinal slot, an endwise movable chuck within the hollow
of the spindle, a cam lever pivotally mounted in the spindle slot and rotatable there-
with, a collar sliding on the spindle and having a rib or projection to engage and
positively rock the cam lever, and a sliding sleeve mounted on the casing and having
a detent movable in the working aperture thereof and adapted to engage and move
the sliding collar, substantially as described.
2. In a dental engine hand piece, the combination with a casing, a sliding sleeve
mounted thereon, a detent working in a slotted aperture of the casing, a sectional
spindle whose front section is hollow and rear section slotted, and the two sections
being threaded for engagement with each other, a cain lever pivoted in the slot of
the rear section, a sliding chuck and a chuck actuating rod within the hollow of the
front spindle section, the heel of the cam being adapted to operate upon the
actuating rod, a sliding collar on the spindle, said collar having an internal rib
working in the groove or slot thereof and engaging the lever and said collar having
a peripheral groove with which the detent of the sliding sleeve engages, substantially
as described.
3. In a dental engine hand piece, a lock operating device comprising a sliding
sleeve having a removable detent provided with a lug adapted to work through an
aperture of the casing, said sleeve having a seat or depression to receive the body
of the detent and an aperture to permit the passage of its lug, the front wall
of the seat being under-cut or dove-tailed and the front end of the detent being
bevelled, and a locking collar having threaded engagement with the sliding sleeve
and adapted to engage the rear end of the detent to secure it in place, substantially
as described.
4. A dental burr having leaves connected by a continuous cutting edge crossing
the axis of rotation of the burr and one or more leaves having a cutting edge
extending to said axial centre at an angle to the cutting edge of the pair and other
leaves having cutting edges terminating short of the axial centre arranged
intermediate the connected leaves, substantially as described.
5. A dental burr having leaves connected in pairs to provide a plurality of
continuous cutting edges crossing the axis of rotation and intersecting each other a

page_text: said axis, and intermediate leaves alternating with the connected leaves, said inter-
mediate leaves having cutting edges terminating short of the axis of rotation,.
substantially as described.
Dated the 5th day of February 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant..