Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Automating Data Acquisition on a Mechanical Equal Arm Balance Used in Large Mass Calibrations



Kevin L. Chesnutwood


This paper focuses on efforts by the Mass and Force Group at the National Institute of Standards and Technology (NIST) to enhance the data taking operations of an approximately 40 year-old mechanical two-pan equal-arm balance used for high-precision mass comparisons in the range from approximately 50 kg to 1134 kg (110 lb to 2500 lb). The repeatability and sensitivity of this manually operated balance (called the Russell balance) has not been found to be matched or surpassed by current digital comparator technology. Therefore, the balance remains a core component of the NIST large mass laboratory. In order to enhance the data taking procedure and reduce the potential uncertainties inherent with human involvement in the data collection process, an automated system was designed and installed to obtain the turning points of the balance taken during calibration that ultimately are used to convert scale units to SI mass units. This paper discusses the advantages of the improved system, the challenges that had to be overcome, and the design, operation, and verification of the automated system.
NCSL International Measure


Mass, Russell Balance, Mechanical Balance


Chesnutwood, K. (2010), Automating Data Acquisition on a Mechanical Equal Arm Balance Used in Large Mass Calibrations, NCSL International Measure, [online], (Accessed May 24, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created June 1, 2010, Updated February 19, 2017