Development of oil film technique to couple power between drive spindle and drill chuck for delicate drilling operations is discussed. Oil film permits application of sufficient pressure, but stops rotating when drill jams. Illustration of equipment is provided

Copeland, C. S.

English

NASA Technical Reports Server

September 1972	 B72-10414 
NASA TECH BRIEF 
Ames Research Center
	 -4r 
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. 
Chuck for Delicate Drills 
A drill rigidly fastened to a rotating spindle is 
broken when the power source can apply more turn-
ing force than can be tolerated by the material from 
which the drill is made. Drills smaller than No. 80 
are particularly delicate and can be shattered even 
when driven by small motors; in particular, breakage 
is nearly inevitable when a small drill is held in a pin 
vise and chucked or colletted in the drive spindle of 
a large machine, especially since it is difficult to sense 
the pressure placed on the tip of the drill. 
The assembly shown in the diagram utilizes an oil 
film to couple power between the drive spindle and 
the drill chuck. The chuck shaft is machined to a slid-
ing fit for a sleeve of convenient diameter; the upper 
part of the chuck shaft is equipped with a stop, which 
may be a pin, washer, or screwed-on cap. The inter-
face between the chuck shaft and the sleeve is kept 
generously lubricated with oil; a low viscosity oil is 
usually sufficient, but higher viscosities .
 may be re-
quired to transfer more power from the sleeve to the 
chuck. 
The weight of the chuck and its shaft usually pro-
vides sufficient pressure for small drills, but additional 
cutting pressure can be obtained by adding weight 
to the chuck or to the top of the shaft. In any event, 
the speed of rotation of the chuck should be kept low, 
and the weight of the chuck and its shaft should be 
at a minimum for a given drill in order to keep "fly-
wheel" energy storage below that required to break 
the drill. When all factors have been properly con-
trolled, sufficient pressure will be automatically ap-
plied to the drill point; the chuck simply stops 
rotating when the drill jams. 
The concept of using an oil film to transfer small 
amounts of energy is also applicable to other situa-
tions where delicate operations do not require posi-
tive power drives. 
Note: 
No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B72-10414 
Patent status: 
No patent action is contemplated by NASA. 
Source: Charles S. Copeland

Ames Research Center

(ARC-10660) 
Category 07 
This document was 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=19720000413 2020-03-17T03:38:51+00:00Z


Chuck for delicate drills

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