1. * GB780091 (A)
Description: GB780091 (A) ? 1957-07-31
Improvements in or relating to taper gauges
Description of GB780091 (A)
COMPLETE SPECIFICATION
Improvements in or relating to Taper Gauges
We, PATENTOOLS LIMITED, of Mitre House,
Western Road, Brighton 1, Sussex, a British
Company, do hereby declare the invention, for which we pray that a
patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement:-
This invention relates to taper gauges and has for its object to
provide an improved, simple and effective construction of device
whereby the degree or angle of taper of a workpiece or object, whether
of circular or rectangular cross-section, may be measured with a high
degree of accuracy.
According to the present invention, a taper gauge comprises two plates
or other flat members disposed in overlapping slidable relation and
provided with spaced or straight edge elements projecting from the
said members to engage at opposite sides of a tapered workpiece or
object, said plates or flat members having coincident slots, pivot
means extending through the coincident slots and including a pinion
engaging rack teeth on one side of the slot in one member and rack
teeth on the opposite side of the slot in the other member and an
adjusting wheel for rotating said pinion, the slots being arranged so
that by rotation of said pinion, said members are movable inwards and
outwards with respect to the pivot means and at the same time movable
about the axis of the pivot means while maintaining symmetrical
disposition of the two members, and means for locking said members
together in any position of adjustment, the device including
cylindrical or semi-cylindrical micrometer-engaging surfaces in planes
parallel to said lines of engagement and at predetermined spacing
whereby the angle or degree of taper may be readily ascertained from

2. the difference in micrometer readings at two positions on the device.
The slot in each member may extend perpendicularly to the line of
engagement of the spaced elements or straight edge carried by the
respective member.
The means for locking said members together may comprise a clamping
knob engaging a screw-threaded portion of a pin extending axially
through the pivot means whereby the plate members may be clamped
between the head of the pin and a spacing sleeve abutting the
adjusting wheel. The knob of the locking means may include a spring
for maintaining the plate members in frictional engagement
Each plate or flat member may be provided with a pair of cylindrical
pins extending perpendicularly to the plate or member, said pins
providing work-engaging surfaces and also micrometer-engaging
surfaces.
For measuring short tapers, or relatively long tapers having a reduced
middle portion, the work-engaging elements may be in the form of
blades or jaws having parallel straight edges, one of which is
comparatively short in length, said blades or jaws being reversibly
attachable to the ends of said cylindrical pins so that either the
short or the long straight edges of said blades or jaws may be
juxtaposed.
The invention is hereinafter described, by way of example, with
reference to the accompanying diagrammatic drawings, in which:
Fig. 1 is a bottom plan view illustrating one embodiment of taper
gauge according to the invention;
Fig. 2 is an end elevation corresponding to Fig. 1 and
Fig. 3 is a section on the line III--III,
Fig. 1.
In carrying the invention into effect according to a particular
embodiment, the device comprises two plate members 1, 2, substantially
of bell or T-shape in plan, said plate members being disposed with the
narrower parts Ia, 2a in slidable overlapping relation. Each plate
member at the extremities of the wider part is provided with a pair of
cylindrical pins 3 projecting perpendicularly downwards from the plate
members and fixed thereto as by means of screws 4, each pair of pins
being spaced at a predetermined distance apart, and the four pins 3
being of such length that when the pins are placed to rest on a flat
surface, the plate members 1, 2 are disposed in horizontal planes. In
each plate member an elongated slot lb, 2b extends centrally in the
narrower part la, 2a respectively of the plate member 1 or 2
perpendicular to the plane in which the respective pair of cylindrical
pins 3 are disposed.
One slot ib is provided with a rack member lc with teeth on one side,
and the other slot 2b with a rack member 2c with teeth at the opposite

3. side. The plate members 1, 2 are held together in slidable relation by
pivot means comprising a pin 5 having a head 5a engaging at the
underside of the lower plate member, a sleeve member 6 rotatable on
the pin and including a pinion 6a engaging with the opposed rack
teeth, and a knurled adjusting wheel 6b disposed at a suitable height
above the upper plate member, the central pin 5 having a
screw-threaded portion 5b projecting above the knurled adjusting wheel
6b for the reception of a cylindrical clamping knob 7 which has a
sleeve portion 7a housing a spring 8 serving to hold the plate members
1,2 together with a suitable degree of pressure maintaining them in
frictional engagement. In order to maintain the pinion 6a centrally
disposed in relation to said slots lb, 2D, the head 5a of the pin 5 is
provided with a shallow shouldered portion Sc having parallel edges
engageable in shallow grooves 2d in the under face of the lower plate
member 2, a bush 5d on the pin 5 adjacent the head 5a slides in the
slot 2b and part of the sleeve 6 above the pinion 6a slides in the
slot lb.
The pinion 6a and knurled adjusting wheel 6b may be formed in one
piece with the sleeve 6, the wheel 6b being spaced from the pinion 6a
sufficiently to permit the pinion teeth to be cut by the use of a
standard milling cutter.
The wheel 6b is spaced from the plate member 1 by a sleeve 9. The
knurled adjusting wheel 6b may be retained in position on the central
spindle 5 by means of a transverse pin 10 extending through the
spindle and held in place by a slotted washer 11 against which the
aforesaid spring 8 bears.
In the use of the device described, the gauge is placed over a tapered
part to be checked and the knurled adjusting wheel 6b is rotated to
bring the four pins 3 into light contact with the work. At the same
time the device should be aligned so that the plate members 1, 2 are
parallel to the- axis of the taper to be measured. Such alignment may
be effected visually, but for very accurate measurement the pins 3
should be supported on parallel blocks. The clamping knob 7 is then
tightened to lock the plate members 1, 2 in the adjusted position and
with a micrometer the distance apart of the pairs of pins 3 is
measured. The difference in the two measurements is divided by a
constant (twice the predetermined spacing of the pins) and the angle
of taper found by reference to a table of sines.
The device may be used as a sine bar by providing means for retaining
two of the pins 3 in light contact and opening the other pair of pins
to a set micrometer reading.
The use of the device may be extended by providing extension blades or
jaws adapted to be detachably fixed to the pins which, for this
purpose, may be provided at the lower ends with portions of reduced

4. diameter forming registers engageable in holes in the blades or jaws
which may be fixed in position by knurled or other screws.
Each blade or jaw has parallel straight edges, one extending to the
full spacing of the pins or beyond the pins, if desired, and the other
being relatively short and being disposed at a middle position in the
length of the blade or jaw and preferably at a greater distance from
the common centre line of the pins than the longer straight edge.
The device according to the invention provides a compact form of gauge
having a large range of adjustment and which, when locked, is of
sufficient rigidity to ensure accurate micrometer measurements.
It will be understood that the invention is not limited to the
particular embodiment hereinbefore described. For example, straight
edge work-engaging elements may be otherwise carried by the plates and
the micrometerengaging surfaces may be constituted by cylindrical or
semi-cylindrical elements other than those engaging the workpiece
providing that the micrometer-engaging surfaces associated with each
plate member are in a plane parallel with the work-engaging surfaces.
What we claim is :-
1. A taper gauge comprising two plates or other flat members disposed
in overlapping slidable relation and provided with spaced or straight
edge elements projecting from the said members to engage at opposite
sides of a tapered workpiece or object, said plates or flat members
having coincident slots, pivot means extending through the coincident
slots and including a pinion engaging rack teeth on one side of the
slot in one member and rack teeth on the opposite side of the slot in
the other member and an adjusting wheel for rotating said pinion, the
slots being arranged so that by rotation of said pinion, said members
are movable inwards and outwards with respect to the pivot means and
at the same time movable about the axis of the pivot means while
maintaining symmetrical disposition of the two members, and means for
locking said members together in any position of adjustment, the
device including cylindrical or semi-cylindrical micrometer-engaging
surfaces in planes parallel to said lines of engagement and at
predetermined spacing whereby the angle or degree of taper may be
readily ascertained from the difference in micrometer readings at two
positions on the device.
2. A taper gauge according to Claim 1, wherein the slot in each member
extends