Gage assembly

A dial indicator gage is mounted to a bar of sufficient length to measure across a part of a certain size. The bar has holes spaced along it for adjustably positioning an anvil carrier at a distance from the indicator plunger which is sufficient to measure a part of the size involved. A handle-operated plunger retractor retracts the indicator plunger into a cavity when the gage assembly is lifted to move it onto a part or off a part to thereby avoid possible damage to the plunger.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to measuring gages for sheet metal, plate 
or bar type parts, and more particularly to a gage which is readily 
adjustable to permit measuring different parts in different ranges of 
size, and yet measure them with a high degree of precision. 
2. Description of the Prior Art 
Various gages for measuring outside dimensions of manufactured parts, are 
well known. Micrometer calipers are probably best known. There is some 
inconsistency in measurement resulting from their use. This is due to 
differences from one inspector to another, or in an individual inspector 
from one time to another, in the feel of tightness of the gage on the part 
during the taking of the measurement. Efforts to avoid these differences 
have resulted in the development of air gages. These are a bit cumbersome 
and expensive for certain uses, and generally result in high volume 
dedicated-measurement stationary applications. Another, more portable 
device, involves a dial indicator on a bar, with a pair of buttons on the 
bar opposite the dial indicator plunger, to cooperate with the plunger to 
provide a three point contact with the part being measured by the 
indicator. These are not readily adjustable to significantly different 
ranges of measurement. The present invention is directed to solving the 
problems associated with the prior art measuring devices. 
SUMMARY OF THE INVENTION 
Described briefly, according to a typical embodiment of this invention, a 
part-bridging bar is provided to support at spaced locations, an anvil to 
engage one margin of a part to be measured, and a dial indicator gage 
positioned to engage the plunger thereof with the opposite margin of the 
part. A plunger retractor assembly is mounted at one end of the bar to 
retract the dial indicator plunger when the gage assembly is lifted to 
place it onto the part to be measured or to remove it from the part to be 
measured. The anvil is mounted to a carrier which is slidable along the 
bar. The carrier is secured to the bar in any desired longitudinal 
position thereon, by a knob-operated clamp. The locations are established 
by precision fit of dowel pins of the carrier assembly in precision 
apertures in the bar.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
For the purposes of promoting an understanding of the principles of the 
invention, reference will now be made to the embodiment illustrated in the 
drawings and specific language will be used to describe the same. It will 
nevertheless be understood that no limitation of the scope of the 
invention is thereby intended, such alterations and further modifications 
in the illustrated device, and such further applications of the principles 
of the invention as illustrated therein being contemplated as would 
normally occur to one skilled in the art to which the invention relates. 
Referring to the drawings in detail, the gage assembly includes the bar 11, 
which can be of any desired length to adequately span or bridge the 
largest part (shown dotted at 12 in FIG. 2) which is to be measured. It 
has two rows of precisely sized and longitudinally spaced apertures 13 and 
14. An anvil and carrier assembly 15 is provided on the bar, and will be 
described in detail hereinafter. 
An indicator and retractor assembly 16 are provided at one end of the bar 
11. This includes a base mounting block 17 fastened to the bar by the cap 
screws 17A. This block 17 receives the dial indicator gage 18 whose 
mounting post 19 is received snugly in an aperture in block 17 and secured 
in the block 17. The post is retained in the block by the screw 22 
recieved through the wall of the block 17. The indicator plunger guide 23 
is received in the cavity or groove 24 in the block 17. The plunger 26 
extends from the end of the guide 23 and is terminated by the tip 27. The 
opposite end of the plunger is shown at 28, and has a head 29 thereon. 
According to one feature of this invention, there is an automatic plunger 
retractor. This includes a plunger retractor block 30 having 
longitudinally extending side legs 31 and a transverse front leg 32 
slidably received on the top of the base mounting block 17, and guidingly 
received in the front end portion of the cavity 34 in the handle and lever 
mounting block 33 which is affixed to the base block 17. This retractor 
block front leg 32 has an upwardly opening notch 31A therein receiving the 
plunger extension 28 through it. The extension has a washer 29 secured to 
it. The washer engages the rear face 32R of leg 32 adjacent the notch 31A, 
so that the retractor is capable of pulling the plunger to the left. The 
width of the space between the legs 31 is greater than the diameter of the 
washer. Therefore, the plunger can be moved to the left a greater distance 
than the distance in space 31B from the rear face 32R to the front edges 
of the legs 31. This provides room for any amount of plunger movement 
required to cause not only full scale readings on the dial indicator, but 
also several total revolutions of the pointer on the indicator, to enable 
the reading of any dimension within the greatest variation of dimensions 
of the parts to be measured with one setting of the gage. The upper part 
of the retracting block 30 has a return spring therein and which will be 
described herein. It urges the block 30 against the front end of the lever 
37 which pivots at 38 in the block 33, for a purpose which will be 
described. A bolt 39 is secured in the block 33 and has the head 41 
thereon. A handle 42 is slidably received on the bolt and has a lower 
flange 43 thereon. The lower face 44 of the flange engages an upwardly 
facing cam surface 46 of the lever 37. It also normally rests on the top 
of the block 33. When the assembly is in this position, the indicator 
plunger is extended in the normal position where it could be making a 
measurement on a part when positioned between the anvil 47 and the plunger 
tip 27. 
The retracting block has a longitudinally extending blind hole 48 in the 
front and extending toward the rear. A return coil spring 49 is received 
in this hole. It pilots on the stem 51 in the rear end of the set screw 52 
threadedly received in the block 33. One end of the spring abuts the rear 
end of the hole in the block 30, and the other end of the spring abuts the 
rear end of the screw 52, whereby the spring urges the block 30 to the 
left, against the lever, as mentioned above. The amount of force can be 
adjusted by adjusting the screw 52. 
The anvil carrier assembly 15 includes a locator base 53 into which the 
threaded body 54 of the anvil is threaded. There is a wrench receiver 
socket 55 in the end of the anvil opposite the end at which the head of 
the anvil is located. The longitudinal position of the anvil in the 
assembly can be closedly adjusted in this manner. The position of the 
screw can be fixed by the set screw 56 threaded into the bottom of the 
base 53. Two socket-head cap screws 57 and 58 are threaded into the base 
53 from above, and seat on the top of the base. The heads of these cap 
screws are precisely sized as they serve as the locating dowels in the 
locating apertures of the bar 11. 
Two posts 61 are mounted to the base 53. Each of these is a shoulder screw 
screwed into the base and having a first shoulder 62 abuttingly engaging 
the top of the base 53. In this way, these screws are tightened against, 
and permanently fixed to the base. A slide 63 is mounted on the bar 11. It 
has the shape of an inverted "U", with the inside side walls of the "U" 
engaging the sides of the bar, and the inside top of the "U" resting on 
the top of the bar. There is a close sliding fit between the sides and top 
of the bar, and the sides and top of the inverted "U" of the slide. The 
slide also has apertures therein which receive the posts 61 through them. 
The slide has spring pockets 64 in it. These receive springs 66 which 
extend out the top of the slide and support the hanger 67. 
The hanger has a pair of apertures in it and which receive the posts 
through them. Each aperture has a counterbore at the top which receives a 
collar 65 in it. The collar has a top edge 65A which receives and supports 
the head at the upper end of the post 61 extending through the collar. A 
clamping bolt 68 is screwed into the hanger, and has a knurled knob 69 at 
the top. Screws 70 threaded into the hanger 67 engage the posts at the 
grooved portion of the post and are tight enough against the post to 
enable a downward force, when applied to the hanger, to force downward the 
posts, and thereby the base 53. 
Operation 
In the use of the gage assembly, the anvil carrier clamp knob is turned 
counterclockwise to withdraw the lower end of the bolt 68 into the hanger 
67. Then the hanger is pushed downward toward the bar 11. The posts 61 are 
thereby pushed downward, pushing the base downward to release the locator 
screw heads 57H and 58H from the locator apertures in the bar 11. Then the 
carrier assembly can be slided along the bar to the position where it will 
be most suitable for measuring the size of part which is to be measured. 
Then the downward force on the hanger is relaxed, whereupon the screw 
heads 57H and 58H will engage the bottom of the bar, or enter a pair of 
apertures if the proper alignment has been obtained. If they do not 
immediately enter a pair of apertures, the base is slided along the bar to 
the extent needed to obtain the desired alignment, whereupon they will 
enter a pair of apertures. Then the knob is turned clockwise to tighten 
the bolt 68 against the bar, and the base 53 is thereby clamped against 
the bottom of the bar. 
Then the gage assembly can be lifted by one hand on the knob, and the other 
hand on the handle 42. Because of the space in the top of the handle under 
the bolthead 41, the handle will rise from the top of the block 33. This 
releases the lever 37, so the force of the spring 49 will pivot the lever 
clockwise, keeping the cam surface engaged with the bottom of the flange 
43. At the same time, the face 32R of the retractor block is driving the 
dial indicator plunger in a retracting mode and will do so until the 
plunger is retracted sufficiently for the tip 27 to be flush with or 
slightly behind the face 17F of the block 17. Then the assembly can be 
placed over and settled on the top of a master gage bar or block of known 
dimension. The anvil 47 is located against one edge of the master, and the 
dial indicator tip 27 is positioned to face the other edge of the master. 
Then the handle is released. This enables the handle to settle down on the 
cam 46, and the weight of the handle, combined with the internal spring of 
the dial indicator itself, will force the retractor block forward, to the 
right in the drawing, and the plunger tip can then engage the master. Then 
the indicator dial can be set in the usual way to provide the proper 
reading of the master dimension. The anvil can be adjusted too for this 
purpose, if needed. Then the gage assembly can be lifted off the master by 
the use of the handle on the left to retract the plunger, and lifting the 
right-hand end with the knob, or otherwise. The gage is then moved to a 
part to be measured, and placed on it for measuring in the same way as it 
was placed on the master. 
The present invention enables the use of a very conventional dial indicator 
gage without any modification of the gage itself, and in a convenient and 
effective way. Most of the parts of the gage of this invention can be 
conveniently made of aluminum for low cost and light weight. The bar can 
be two feet long, for example. 
Some alternative construction features which may be mentioned here include 
use of a spring in addition to or instead of the weight of the handle, to 
retract the plunger. Also, instead of two rows of holes and associated 
detent pins, a series of longitudinally spaced grooves transverse to the 
length of the bar could be used, and receive a detent bar or ball mounted 
to the base 53. Therefore, while the invention has been illustrated and 
described in detail in the drawings and foregoing description, this is to 
be considered as illustrative and not restrictive in character, the 
invention being defined in the following claims.