Easily made, pen-light battery operated production check gauge has probe-activated switch with fail-safe features to insure proper operation. Parts can be reliably and quickly checked. Gauge is equipped with tolerance band adjustment and can use interchangeable probes for different applications. Accompanying tester permits frequent check of calibration

Rauch, E. P.

English

NASA Technical Reports Server

Insulator/5 
Activation 
Switch
A
Cap 
Conductor 
and Spring 
Gauge Switch 
Upper Contact 
Adjustment 
Lock 
Insulated 
Contactor 
Lower Contact 
Off
On
Metal 
Ba
May 1973	 B73-10150 
NASA TECH BRIEF 
Lyndon B Johnson Space Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to-the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
A Simple, Accurate Depth Check Gauge 
 Probe 
(Interchangeable) 
I 
Part	 Thread Insert 
(To Be Gauged) 
Depth Check Gauge 
S 
-	 (continued overleaf) 
This documentwas prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
	 -
https://ntrs.nasa.gov/search.jsp?R=19730000150 2020-03-17T07:07:35+00:00Z
The problem: 
Present methods used to measure the depth of 
recesses in parts during quality control inspections 
involve the use of depth calipers, micrometers, or 
complex indicators. These methods are time consuming, 
and their reliability is dependent upon the person 
making the test. 
The solution: 
An easily made, pen-light-battery operated production 
check gauge has a probe-activated switch with fail-safe 
features to insure proper operation. With this gauge, 
parts can be more reliably and quickly checked. 
How it's done: 
The figure shows the check gauge as it is used to 
inspect a typical part. To ready the gauge for use, the 
activation switch is turned on. This releases the battery 
so that the gauge indicator light remains on except 
during use. Then the nylon probe is inserted into the 
recess to be measured, with the base of the gauge held 
flat against the part. 
If the hole being tested is too deep, the gauge switch, 
which is attached to the probe, touches the lower 
contact points; the circuit is complete; and the light is 
on. This is the case shown in the illustration. 
If, however, the hole is within tolerance limits, the 
switch button 
will be held between the upper and lower 
contacts, and the light will remain off. Thus, when the 
light is off, the measured recess is within the tolerance. 
An "on" light indicates rejection. 
When the gauge is removed from the recess, the light 
goes on to indicate that the gauge is operative. After 
use, the activation switch may be turned off for storage 
of the gauge.
The gauge is equipped with a tolerance band adjust-
ment and can use interchangeable probes for different 
applications. An accompanying tester permits frequent 
checks of the calibration. Recalibration, or the installa-
tion of different probes, requires precision depth gauge 
measurement. Calibration seals should be applied on 
the tester. 
The gauge has been used to check that thread inserts 
are installed within 0.020 inch (0.05 cm) of being flush. 
The testerwas set at 0.001/0.019 inch (0.025/0.048 cm). 
Closer tolerances could be held with more precisely 
machined switch parts. 
Notes: 
1. The versatility of this device may be increased 
through the addition of a micrometer scale to permit 
adjustment of the tolerance levels. 
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Lyndon B. Johnson Space Center 
Code JM7 
Houston, Texas 77058 
Reference: B73-10150 
Patent status: 
NASA has decided not to apply for a patent. 
Source: E. P. Rauch of
Rockwell International Corp. 
under contract to
Johnson Space Center 
(MSC-17166)
. 
. 
B73-10150	 Category 06


A simple, accurate depth check guage

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