Improvements in Micrometers or Micrometer-calipers.
Year: 1889

page_text: Date of Application, 30th Sept., 1889
Complete Specification Left, 30th July, 1890-Accepted, 30th Aug., 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by LAROY SUNDERLAND STARRETT, of No. 160, Main
Street, Athol, Worcester County, Massachusetts, United States of America,
Manufacturer of Mechanical Tools.]
Improvements in Micrometers or Micrometer-calipers.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co. Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature of
this invention to be as follows:-
This invention relates to the class of gauges or calipers having a spindle screw-
threaded at one end to engage with a corresponding thread within a stationary tubular
barrel provided with longitudinal graduations, a peripherally-graduated sleeve fixed to
the outer end of the spindle revolving outside of said barrel.
The object of the present improvements is to guard against back-lash or lost motion
in the screw thread and compensate for wear therein, thus securing a uniform tension;
and also to provide an efficient locking device to hold the spindle firmly at any desired
position.
'
1 accomplish the first of these objects by means of a split bushing screwed into the
outer end of the tubular barrel, such bushing being internally threaded to engage with
the spindle, and having along one or both of its sides a section or tongue lying
between two slots, and spring inwardly at its free end toward the axis, being thereby
slightly lessened in axial length, and depressed more closely into the threads of the
spindle. These minute changes of position of the threads of the spring-tongues with
relation to those of the rigid remainder of the bushing, and of the spindle, press back
the threads of the spindle firmly against those of the bushing, and suffice to take up,
automatically, all end-play of the spindle, to compensate for any wear thereof, and to
ensure a perfect fit of the screw-threads.
This bushing is prolonged by an unthreaded, slotted, tubular extension forming
connected spring-fingers, surrounding an unthreaded part of the spindle, and con-
verging at their forward free ends and caused to grip the spindle by means of a
thimble nut screwed into the inner end of the barrel or frame, and having a tapering
hore which forces the prongs inwardly against the spindle. This constitutes the
second feature of my invention.
Dated this 30th day of September 1880
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Micrometers or Micrometer-calipers.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 gauges of the kind or class wherein a spindle provided
with a screw-threaded portion at one end is adapted to engage with a corresponding
thread within a stationary tubular barrel provided with longitudinal graduations, a
peripherally graduated sleeve fixed to the outer end of the spindle revolving outside
of said barrel.
The object of the present improvements is to guard-against back-lash or lost inotion

page_text: in the screw thread and compensate for wear therein, thus securing a uniform tension;
and also to provide an efficient locking device to hold the spindle firmly at any desired
position.
I accomplish the first of these objects by means of a split bushing screwed into the
outer end of the tubular barrel, such bushing being internally threaded to engage
with the spindle, and provided with one or more sections or tongues each formed
between two slots, the said sections in cases where there are more than one being
arranged diametrically opposite one another and each being sprung or depressed
inwardly at its free end toward the axis, whereby the horizontal distance between its
extremities is slightly lessened and the threads thereon are caused to enter more
closely into the threads of the spindle. These minute changes of position of the
threads of the spring-tongues with relation to those of the rigid remainder of the
bushing, and of the spindle, press back the threads of the spindle firmly against those
of the bushing, and suffice to take up, automatically, all end play of the spindle, to
compensate for wear thereof, and to ensure a perfect fit of the screw-threads.
This bushing is provided with an extension or prolongation consisting of an
unthreaded, slotted, tubular extension forming connected spring fingers, surrounding
an unthreaded part of the spindle, and converging at their forward free ends and
caused to grip the spindle by means of a thimble nut screwed into the inner end of
the barrel or frame, and having a tapering bore which forces the prongs inwardly
against the spindle. This constitutes the second feature of my invention.
In the drawing, Figure 1 is a longitudinal section through the sleeve, the barrel
and enclosed parts except the spindle, which is seen in elevation. Figure 2 is a side
view of the instrument complete, while Figure 3 represents, detached, the internal
parts. Figure 4 is an enlarged end view of the tongued bushing, two tongues being
here represented.
The anvil A is located permanently at one end of the neck or body B, the cylindrical
barrel C extending rigidly from the other end. The spindle D has an exposed
cylindrical end and an enclosed screw-threaded portion, while its outer end has the
milled head or cap E terminating in a milled tip or thumb-piece G, of considerably
less diameter than the spindle or head E, for the purpose of increasing the speed of
rotation. The head E carries the rotating sleeve F peripherally graduated at its
bevelled end as heretofore, and the barrel has the usual straight line of graduations,
see Figure 2.
H represents an interually-threaded bushing with which the screw-threads of the
spindle Dengage. This bushing has near its outer end a short threaded portion screwing
into an internal thread in the barrel C, the collar or end of such bushing having
nick to facilitate screwing it into place.
al
In order to prevent any back-lash whatever between the threaded spindle and the
bushing, I form two slots longitudinally through one side only, or through opposite
sides of the bushing, from its inner end nearly or quite to the collar, leaving
between each pair of slots a tongue I, which tongue or tongues is weakened or
reduced in thickness near the collar and depressed inwardly at the free end, bringing
each tongue or its free end somewhat nearer to the axis of the spindle than is the
body of the bushing. This depression of the tongue, (seen in duplicate and somewhat
exaggerated in Figure 4) causes the portion of the screw-threads formed on the inner
surface of the tongues to press down with an elastic pressure into the threads of the
spindle and, by the shortening tendency, to draw the spindle back into close contact
with the working faces of rigid threads of the bushing, thus making constantly
a close fit. The tongue being integral with the collar 4, its free end (when so sprung
inwardly) moves in a short, arc, and, in a most minute degree, shortens the horizontal
distance between its extremities the sections of threads upon its inner surface being
very slightly to the rear of the other portions within the rigid part of the bushing.
The elasticity of the tongue gives it a spring pressure against the threads of the
spindle, causing them to engage closely, and without play, with the threads of the
bushing proper.
The remaining feature of my present improvement is illustrated in Figures 1 and 3.

page_text: A series of spring fingers J are caused to grip the spindle by screwing an annular
nut K into the inner end of the barrel, the flaring hore of the nut surrounding and
forcing inwardly the tapering tips of said fingers. To do this the fingers should be
held stationary within the barrel, and I prefer to so hold them by the means shown in
Figure 3. The fingers J are longitudinal sections of a thin tube, slotted from one
end almost to the other. A shoulder L is formed at the outer or unslotted end of
this tube of a form to engage with a like shoulder at the inner end of the stationary
bushing H. When the spring fingers J are expanded in their normal position there
is just room for the spindle to revolve freely within them; but when the nut K is
screwed towards said finger it surrounds their tapering free ends and forces them
each toward the axis and into close contact with the cylindrical surface of the spindle
so that it is locked fast frictionally. The periphery of the nut K is milled to facilitate
turning it. The proportions of the parts are such that the nut K clamps the fingers J
firmly upon the spindle just before the milled end of said nut strikes the inner end of
the rigid barrel C.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is
First. In a micrometer gauge, the bushing H, secured within the outer end of the
barrel and internally threaded to receive the spindle, and formed with the depressed
spring-tongue or tongues I, cut away or weakened near the collar substantially as
and for the purpose set forth.
Second. In a micrometer gauge, the bushing H, externally threaded near its outer
end only to screw into the barrel, internally threaded to engage the threaded portion
of the spindle, and provided with one or more integral tongues I, each free at its
inner end from the screw threads of the barrel and yielding to approach the axis of
the spindle, for the purpose set forth.
Third. In a micrometer gauge, the combination of the barrel, the rotating spindle
therein, the interposed clamping fingers, and the annular locking nut having an
exposed milled periphery and adapted to contract said fingers around the unthreaded
part of the spindle, substantially as set forth.
Fourth. In a micrometer gauge the unthreaded clamping fingers, held from
rotation within the barrel and converging or tapering externally at their forward free
ends, in combination with the annular nut screwed into the inner end of the barrel
at its junction with the curved body and adapted to compress said tapering fingers for
the purpose set forth.
Fifth. In a micrometer gauge, the bushing H secured in one end of the barrel and
formed with a shoulder at its inner end, and the spring fingers joined at one end in a
tube shouldered to fit the end of said bushing, in combination with the barrel, the
spindle, and the locking nut, arranged substantially as set forth.
Sixth. The improved micrometer gauge constructed substantially as hereinbefore
described with reference to the accompanying drawings and for the purpose set
forth.
Dated this 2011 dose of T.... 1900
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.