Combination indexer and drive unit drills equally spaced circular hole patterns on rotary tables. It automatically rotates the table a distance exactly equal to one hole spacing for each revolution of a special idler gear

Johns, M. F.

English

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August 1966	 Brief 66-10383 
S	 NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Gear Drive Automatically Indexes Rotary Table 
RotaryTable
The problem: 
To develop a quick and accurate indexing method 
for drilling equally spaced circular hole patterns on 
rotary tables. The manual layout and indexing tech-
niques presently used are too slow and place a pre-
mium on operator skill. 
The solution: 
A combination indexer and drive unit which auto-
matically rotates the table one hole spacing for each 
revolution of a special idler gear. 
How it's done: 
The unit is installed to provide power to a con-
ventional rotary table through the original drive
pinion and ring gear. An index gear fabricated with a 
number of teeth equal to the number of holes in the 
circular pattern to be drilled is 'insfalled on the origi-
nal table drive shaft on the end opposite the drive 
pinion. An idler gear having a number of teeth nu-
merically equal to the gear ratio between the original 
pinion and table ring gear is then meshed with the 
index gear. A variable speed dc motor with magnetic 
clutch is connected to the drive shaft, and an assort-
ment of stop and limit switches is installed in con-
nection with the idler gear. 
When the unit is actuated, the motor drives the 
index gear, the table, and the idler through the mag-
netic clutch. The limit switches are arranged so the 
(continued overleaf) 
AMk 
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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.
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idler makes exactly one revolution after actuation 
before the clutch is disengaged. The gear ratios in the 
system are designed so the table rotates a distance 
exactly equal to one hole spacing for each revolution 
of the idler gear. After the hole is drilled, the unit 
is again actuated for another automatic cycle. 
When another circular pattern having a different 
number of holes is to be drilled, the index gear is 
removed and a new one is installed having the same 
number of teeth as the holes in the new pattern. 
Notes: 
1. This unit has maintained tolerances within ±0.001 
inch true location on hole patterns with up to 48 
inches between centers.
2. Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B66-10383 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546
Source: M. F. Johns

of North American Aviation, Inc.

under contract to

Marshall Space Flight Center

(M-FS-753) 
Brief 66-10383	 Category 05


Gear drive automatically indexes rotary table

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