Fixture for setting the stationary gaging contact on a dial bore gage

A gaging fixture for presetting the radially extended position of a stationary work engaging contact on a dial bore gage or like instrument, wherein the stationary work engaging contact is mounted on a member threadedly engaged with the gage, which member carries a threaded locking member for locking the threaded member and the stationary work engaging contact thereon in predetermined and determinable positions of adjustment, said fixture including a first member having a portion for engaging the member on which the stationary work gaging contact is located, and a second member movable axially and rotatably relative to the first member and having a portion thereof engageable with the member for locking the stationary work engaging contact in predetermined radial positions, the portions of the said first and second members being constructed and positioned to simultaneously engage the member on which the stationary work engaging contact is located and the locking member associated therewith in only one predetermined relative position, and cooperating indicator means on said relatively movable members calibrated to indicate the radially extended position of the stationary work engaging contact for any setting of the fixture over a predetermined range of movement of the threaded member on which the stationary work engaging contact is located.

Dial bore gages and like instruments for measuring the size and surface 
characteristics of bores are well known devices, have wide application and 
are used for many purposes. Typical of such dial bore gages is the dial 
bore gage disclosed in Rutter U.S. patent application Ser. No. 655,892, 
filed Mar. 11, 1976 and assigned to Applicant's assignee. As indicated in 
this copending case, it is well known to adjust or select a diameter or 
range of measurements that can be measured by a particular dial bore gage, 
and when this is done a particular gage can be used to accurately gage and 
measure many different diameters simply by setting the radially extended 
position of the stationary work engaging contact. Heretofore the usual way 
for adjusting the position of the stationary or non-movable contact has 
been to mount the contact on a member that is threaded into the work 
engaging end of the gage, and this contact is then threaded inwardly and 
outwardly to a desired position and locked in position by means of a 
locknut. It is important to be able to position the stationary work 
engaging contact at a particular location taking into account the diameter 
of surface on workpiece to be measured. Being able to locate and hold a 
desired setting while tightening the locknut is difficult and imprecise 
when using known members and the like and when this is done some means are 
also still required to indicate when the desired setting is obtained. To 
accomplish this using known means requires trial and error setting 
techniques since merely tightening up on a locknut will usually produce 
some error unless means are provided to hold the setting while the locknut 
is tightened. The accuracy of such a setting procedure using known setting 
means depends on the skill and experience of the person making the setting 
and on the precision of the parts involved. The obvious limitations and 
shortcomings of such procedures are easily recognized, and as a result it 
has been difficult if not impossible using the known means to quickly and 
accurately preset the stationary work engaging contact so that the gage 
can then be accurately set and used to measure or indicate a particular 
diameter. It is especially difficult to accomplish the aforesaid 
accurately while the gaging contacts are engaged with a ring gage or other 
standard. For these and other reasons, the ability to accurately preset 
dial bore gages and like instruments has been limited, and it has not been 
possible or practical to set such gages precisely enough so that the gage 
can then be acurately set within a range for each different dimension to 
be measured. The present invention overcomes these and other limitations 
and shortcomings of known gage setting devices, and teaches the 
construction and operation of a setting fixture which is relatively simple 
structurally and operationally, and one which can be used as a coarse 
setting device to quickly preset a gage to any setting within the range 
thereof. 
It is therefore a principal object of the present invention to teach the 
construction and operation of a novel setting fixture for use in setting 
the radial position of a work engaging contact such as the stationary work 
engaging contact of a dial gage or like instrument. 
Another object is to provide a relatively simple inexpensive tool which can 
be operated even by persons having relatively little skill and training. 
Another object is to increase the range of dimensions that can be 
accurately indicated using a dial bore gage. 
Another object is to enable fairly accurate coarse presetting of a work 
engaging contact on a gage or like device to any position within the range 
of the adjustment means. 
Another object is to facilitate adjustment of a threaded member while 
retaining a locking member therefor in an unlocked position. 
Another object is to enable a dial bore gage or like instrument to be 
coarsely preset so that it can thereafter be accurately set to a desired 
dimension using ring gages or other dimensional standards to achieve the 
desired gaging accuracy. 
Another object is to enlarge the range of accurate setting positions of 
dial bore gages.

These and other objects and advantages of the present invention will become 
apparent after considering the following detailed specification which 
discloses a preferred embodiment of the present device in conjunction with 
the accompanying drawings, wherein: 
FIG. 1 is a side elevational view in cross section taken on the axis of a 
setting fixture constructed according to the present invention; 
FIG. 2 is a side elevational view of one of the relatively movable portions 
of the fixture of FIG. 1; 
FIG. 3 is a top view of the fixture portion shown in FIG. 2; 
FIG. 4 is a left end view of the fixture portion of FIG. 3; 
FIG. 5 is a right end view of the fixture portion of FIG. 3; 
FIG 6 is a side elevational view of another portion of the setting fixture 
of FIG. 1; 
FIG. 7 is a left end view of the fixture portion of FIG. 6; 
FIG. 8 is a right end view of the fixture portion of FIG. 6; 
FIG. 9 is a side elevational view of a member attached to the fixture 
portion shown in FIGS. 6-8; 
FIG. 10 is a top view of the member shown in FIG. 9; 
FIG. 11 is a left end view of the member shown in FIG. 10; 
FIG. 12 is a side view of an adjustable stationary gaging point assembly 
for use on a dial bore gage; 
FIG. 13 is a left end view of the assembly shown in FIG. 12; and, 
FIG. 14 is a side elevational view of a dial bore gage equipped with an 
adjustable stationary gaging contact assembly similar to that shown in 
FIGS. 12 and 13, said view also showing in cross-section a setting fixture 
operatively engaged with said assembly. 
Referring to the drawings more particularly by reference numbers, number 20 
identifies a setting fixture constructed according to the present 
invention. The setting fixture 20 includes first and second relatively 
movable portions 22 and 24. As shown in FIG. 1, the portion 22 is an 
elongated cylindrical member having a bore 26 which extends into it from 
one end and communicates with a smaller diameter bore portion 28 adjacent 
the opposite end. The member 22 also has an enlarged diameter portion 30 
which is knurled on its outer surface for ease of gripping, and the end of 
the member 22 has two spaced endwardly projecting portions 32 and 34 which 
have respective opposed surfaces 36 and 38 formed thereon. The surfaces 36 
and 38 are parallel to each other and are located different distances from 
the axis of the member 22, the portion 32 being shown somewhat thicker in 
the radial direction than the portion 34 (see FIG. 4). As shown in FIG. 2 
the member 22 has a cylindrical body portion 40, and a scale 42 is formed 
on the outer surface thereof and extends in an axial direction. 
The member 24 is likewise cylindrical in shape and has a body portion 44 
(FIGS. 1 and 6) which has a counterbore 46 extending into it from one end. 
The counterbore 46 is slightly larger in diameter than the cylindrical 
body portion 40 of the member 22 and receives the body portion 40 therein 
as clearly shown. The body portion 44 has an enlarged diameter portion 48 
which is knurled on its outer surface, and the portion 44 has a reduced 
diamer portion 50 which extends from one end of the knurled portion 48 and 
has its opposite end connected to a tapered end portion 52. A 
circumferential scale 54 is formed on the tapered end portion 52, and the 
scale 54 cooperates with the axial scale 42 on the member 22 during 
operation of the device. The member 24 has a smaller diameter bore 56 
which extends from one end of the counterbore 46 to a threaded bore 
portion 58 which extends therefrom to the opposite end of the member 24 
from the tapered portion 52. The threaded bore 58 receives a threaded 
locking member or plug 60 (FIGS. 1 and 8) which is adjusted at the factory 
to accurately locate a member such as member 66 to be described later in 
the member 24. The member 24 also has a radially extending threaded bore 
62 which extends from the outer surface thereof to the bore 56. The bore 
62 receives a locking member or set screw 64 which is used to lock the 
member 66 in position in the bore 56. 
The member 66 is rod shaped (FIGS. 9-11) and has a cylindrical rod portion 
68 of the same diameter as the diameter of the bore 56. The member 66 also 
has an end portion 70 which is somewhat larger in diameter than the rod 
portion 68 and includes a round portion 72 of approximately the same 
diameter as the bore 26 in the member 22. The rod member 66 is positioned 
extending through the member 22 (FIG. 1) with the rod portion 68 extending 
into the bore 56. The accurate location of the rod portion 68 in the bore 
56 is important for reasons which will become apparent later, and this 
position is locked against movement by means of the set screw 64 in the 
radial bore 62. In this position, the threaded member or plug 60 abuts the 
end surface 74 of the member 66 and this provides means to accurately 
locate the member 66 therein during assembly. Adjustment of the member 60 
is preferably done at the factory and normally will not be changed in the 
field. Preventing field adjustment can be assured by providing means to 
lock the member 60 in the bore 58. With the members assembled and 
connected as disclosed in FIG. 1, the member 22 can move axially and 
rotationally relative to the member 24, being limited in these movements 
only by engagement between the enlarged end portion 70 on the member 66 
and shoulder 75 formed at the juncture between the bores 26 and 28. This 
engagement prevents complete separation of the portions 22 and 24. 
Referring again to FIGS. 9-11, the enlarged end portion 70 of the member 66 
is shown bifurcated by a slot 76 which extends inwardly from the free end 
thereof. The enlarged end portion 72 of the member 66 is formed by the 
spaced endwardly extending portions 78 and 80 which are of different 
radial thickness, and the members 78 and 80 have respective surfaces 82 
and 84 thereon which are in spaced parallel relation. With the radial 
thicknesses of the portions 78 and 80 being different, it means that the 
space formed therebetween is offset somewhat relative to the axis of the 
device and this is clearly evident in FIGS. 10 and 11. The reasons for 
this off axis condition is so that the portions 78 and 80 can only move 
into engagement with a member to be turned thereby in one position, and 
this is important to the operation of the device. The same is also true of 
the spaced portions 32 and 34 on the member 22. The particular manner in 
which the portions 32 and 34 and the portions 78 and 80 engage threaded 
members on the dial bore gage during adjustment is important to the 
operational accuracy of the subject fixture because it makes the scales 42 
and 54 cooperate in such a way as to give a fairly accurate direct reading 
of the radial position to which the stationary work engaging contact is 
adjusted as will be described more in detail in connection with FIGS. 
12-14. 
In FIG. 12 the details of a stationary but adjustable gaging contact 
assembly 90 for a dial bore gage 92 of the type shown in FIG. 14 is shown. 
The assembly 90 includes a threaded portion 94 which cooperates with a 
threaded bore 95 provided therefor in the gaging end portion 96 of the 
dial bore gage 92. A locking member 98 is mounted on the threaded portion 
94 of the assembly 90, and when the assembly 90 is in a desired radial 
position on the gage 92, the member 98 is rotated to be against the gaging 
portion 96 to retain the setting. The assembly 90 has a head end portion 
99 with a work engaging member 100 mounted on the free end thereof. The 
member 100 is one of two portions of the gage 92 which engage the work 
during a gaging operation. The other work engaging member is the movable 
work engaging member 102, and the member 102 engages the surface being 
gaged diametrically opposite from the member 100. The gage 92 may also 
have work engaging centralizer members which engage the work surface to 
make sure that the contacts 100 and 102 are on a diameter of the work 
during gaging, but the centralizers and other gage portions are not parts 
of the present invention as such. The movable work engaging contact 102 is 
operatively connected to dial portions 104 of the gage 92 in a manner 
known to the prior art. 
The purpose of the subject fixture 20 is to provide means to fairly 
accurately preset the stationary work engaging assembly 90, and 
particularly the work engaging contact 100 thereon, so that the gage 92 
with this coarse setting can be used to accurately gage any diameter of 
work surface within a close range of coarse adjustment obtained. It is 
recognized, however, that some standard or fine setting device may be 
required to achieve the final gaging accuracy desired. With the subject 
fixture it is possible to make the coarse adjustment easily and quickly 
without the awkwardness normally associated with making adjustments 
especially adjustments where one threaded member is used to lock the 
position of another. The head end portion 99 of the assembly 90 and the 
lock nut 98 are constructed to cooperate with the subject fixture during 
adjustment thereof as will be described. 
Referring to FIG. 14, the threaded portion 94 of the assembly 90 is shown 
threaded into the threaded bore 95 provided therefor in the gaging portion 
96. While in this position and using the subject setting fixture installed 
on the gage as shown, the locking member 98 is loosened on the threaded 
portion 94 by engagement thereof with means on the fixture so as to be out 
of engagement with gaging portion 96. It is now possible to turn the 
assembly 90 in either direction as required to reach a desired adjustment. 
The locking member 98 as already stated is threadedly engaged with the 
threaded portion 94, and is constructed to have two parallel opposite 
surfaces 108 and 110 (FIG. 13). The surfaces 108 and 110 as clearly shown 
are parallel and are spaced different distances from the axis of the 
assembly 90. Furthermore, the distance between surfaces 108 and 110 is the 
same as the distance between the opposed parallel surfaces 36 and 38 on 
the respective portions 32 and 34 of the member 22. This is so that the 
surfaces 36 and 38 will engage the surfaces 108 and 110 in one position 
only as shown in FIG. 14. The fact that these surfaces are only engageable 
in one position is important because this is one of the conditions that is 
necessary for the scales 42 and 54 to cooperate and to give a direct 
reading of the gage setting. 
The work engaging member 100 on the assembly 90 is mounted on an endward 
extension 116 of the assembly 90, and the portion 116 has opposite 
parallel surfaces 118 and 120 (FIGS. 12 and 13) which are likewise spaced 
different distances on opposite sides of the axis of the assembly 90 and 
in position to be engaged by the respective parallel surfaces 82 and 84 on 
the portions 78 and 80, of the member 66 (FIG. 10). This is so that the 
members 24 and 66 and the assembly 90 can become cooperatively engaged 
also in one position only as shown in FIG. 14. It is now apparent that 
both the locking member 98 and the assembly 90 can only be simultaneously 
engaged with the members 22 and 24 in one position. This is what makes it 
possible for the graduated scales 42 and 54 to cooperate and be calibrated 
to directly indicate the position of the work engaging member 100 in all 
positions of the assembly 90 on the gage 92. Because of this an operator 
can, by loosening the locknut 98, preset the position of the work engaging 
contact 100 and thereafter lock the gage in this condition. This can be 
done quickly and with little or no special skill or training. 
When the setting fixture 20 is operatively engaged with the dial bore gage, 
it is a simple matter while holding onto the members 22 and 24 to first 
rotate the member 22 to loosen the locking member 98, and while holding 
the locking member in its loosened condition, rotate the member 24 and the 
engaged assembly 90 to achieve a desired setting position as indicated by 
the scales 42 and 54. When the member 24 is rotated in one direction, the 
assembly 90 will move inwardly reducing the effective gaging diameter, and 
when the member 24 is rotated in the opposite direction the assembly 90 
will move outwardly increasing the gaging diameter. When the desired 
position for the member 24 has been reached as determined by the relative 
positions of the scales 42 and 54, the member 22 can be turned slightly 
while maintaining and moving the member 24 in concert therewith to retain 
the desired setting, and to bring the lock member 98 into locking position 
against the gage portion 96. This is easy to accomplish. 
The scale 42 on the member 22 (FIG. 2) is shown divided into equal 
increments and subincrements, and the scale 54 is divided into equal 
increments extending around the surface thereof, positions for twenty-five 
equal increments being indicated in FIG. 6. The scale, as shown, is 
arranged so that one complete rotation of the member 22 relative to the 
member 24, taking into account the dimensional characteristics of the 
threads on the assembly 90, will change the radial position of the 
assembly 90 by an amount equal to the distance between two adjacent scale 
lines on the scale 42. Obviously other increment spacings and scales can 
also be used depending on the threads selected for use on the assembly 90. 
The purpose of the slot 76 which extends in from the free end of the member 
66 (FIG. 9) is to enable the enlarged end portion 70 thereof to have a 
somewhat larger unstressed diameter than the diameter of the bore 26 in 
which it moves. This is done so that there will be some friction between 
the members 66 and 22 which is desirable to prevent looseness and to 
improve the feel of the device. 
A dial bore gage can be provided with any desired number of threaded 
assemblies such as the assembly 90, and each such assembly can have a 
different length to cover a different range of measurements. Each 
different length assembly can be adjusted within its portion of the scale 
42 using the subject fixture. This means that the same fixture can be used 
to preset a plurality of different length assemblies 90 to cover the very 
wide range of possible gage diameters. 
Thus there has been shown and described a novel setting fixture for 
locating and presetting the position of a threaded member, including a 
threaded member having a work engaging contact thereon, which setting 
fixture fulfills all of the objects and advantages sought therefor. It 
will be apparent to those skilled in the art, however, that many changes, 
modifications, variations and other uses and applications for the subject 
setting fixture are possible, and all such changes modifications, 
variations, and other uses and applications which do not depart from the 
spirit and scope of the invention are deemed to be covered by the 
invention which is limited only by the claims which follows.