Machine grinds fines to appropriate micron sizes with the least biological trauma and greatest degree of reproducibility. Device controls destruction of material so that recovery of microorganisms is as great as possible and protects operation and grinding products from exogenous contamination

Houser, C. P.

Pesch, W. A.

English

NASA Technical Reports Server

I 
rcli 19-1	 Brief 7!-1009 
NASA TECH BRIEF 
Marshall Space Flight Center
	 W 
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 aubscription 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 Off i ce, NASA, Code KT, Washington, D.C. 20546. 
Miniature Grinder for Solid Specimens 
A miniature grinder can be used to grind a 
wide range of solids (not including hardened steel 
and harder substances) to fines or ribbons. Because 
the machine was designed primarily for microbi-
The purpose of the device is to control the 
destruction of material so that the recovery of 
microorganisms is as great as possible. Other de-
vices for microbial assay by destruction do not 
Cutter Assembly	 Cutter Motor 
Chuc 
ology, the entire operation and the grinding products 
are protected from exogenous contamination. Fines 
are ground to appropriate sizes in the micron range 
with the least biological trauma and the great-
est degree of reproducibility. The sizes are meas-
ured by a fiber-optics sensor.
include a means for progressively removing the 
grindings from the destroyed area before destruc-
tion is complete. Nor do they provide sufficient 
control of the destructive process, or a sensor 
capability for monitoring the various parameters 
of biological trauma. 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000058 2020-03-17T02:18:04+00:00Z
In the miniature grinder, a sealed cylinder of 
methyl methacrylate houses the grinding operation 
(see fig.). Separate electric motors move the speci-
men chuck linearly and rotate the cutting assembly. 
Both speeds are carefully controlled. 
The cutter's geometry varies, and overtravel is 
prevented by a limit switch. Temperature is main-
tained by a heat sensor with a purge tank. The 
grinder can operate either horizontally or vertically, 
and the cuttings fall through the lower wall of the 
grinding chamber to a compartment from which they 
are sucked asceptically by vacuum to a sterile 
filter. 
The following items are incorporated: purge-con-
trol valve; purge gage; pyrometer; dwell motor; 
pressure gage; automatic control and reset for for-
ward-reverse drive; strain-gage sensor bolt; clutch; 
safety limiting switch and dial indicator for pre-
setting the controls in 0.002 cm. (0.001-in.) increments.
Note: 
Requests for further information may be directed 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&TS-TU 
Huntsville, Alabama 35812 
Reference: TSP7 1-10059 
Patent status: 
No patent action is contemplated by NASA. 
Source: W. A. Pesch and C. P. Houser of

Hayes International Corp.

under contract to

Marshall Space Flight Center

(M FS-20005) 
Brief 71-10059 Category 05


Miniature grinder for solid specimens

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