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Humboldt State University ® Department of Chemistry
Robert A. Paselk Scientific Instrument Museum
Instrument Parts/Repair Help The information provided via this page is intended to aid those repairing/restoring old instruments. It consists of responses I have made over the years to requests for help with restoration.
If you are interested in replacing missing parts, I have linked a set of emails describing a successful restoration of a missing chain by a user of this site as an example of what can be done - Rich
Chemical Balances A brief set of instructions for cleaning a balance, originally provided by Fisher Scientific, is provided on-line: Directions for Cleaning a Balance From: Fisher Scientific Company. Modern Laboratory Appliances (Catalog 90). Fisher Scientific Company and Eimer and Amend (1942, reprinted 1946) p 48.
The operation and general care of chemical balances may be found in any vintage (<1975) analytical chemistry text. A fairly thorough early treatment is available here on-line: Weighing from Smith, George McPhail. ...QUANTITATIVE CHEMICAL ANALYSIS ... (1921).
A more advanced treatment on the set-up and repair of balances is also available on-line: The Use and Care of a Balance by Peter J. Krayer (1913). This treatment does not seem to have been superceded in English, and is highly recommended.
A general description of the care and operation of analytical balances focusing on Christian Becker Chain balances is also provided on line: Care and Use of Analytical Balances. This is the complete text of a brochure provided by Christian Becker division of Torsion Balance Company (1952)
Instructions for Assembly and Adjustment of Christian Becker Chainomatic Balances. These typed instructions were found under an instrument in HSU's physical chemistry lab. They probably came with our AB-2 balance in the 1950's. pg 1, pg 2, pg 3, pg 4, pg 5.
Some of the important variations of the Christian Becker line of chain-weight balances are illustated and briefly described on-line in: Christian Becker Analytical Balances from Braun-Knecht-Heiman Co., Catalog No. 40, Laboratory Instruments Apparatus Supplies, (1940)
The directions provided in the lid of the box originally carrying the beam, pans etc. for a SeKo two pan balance is provided in two resolutions: SeKo Directions for Setting up a Balance from Seederer-Kolbush (c. 1960) (Higher Res)
Balance parts: Illustrations and specifications for some parts commonly needing replacement are given below. All dimensions were determined with dial calipers unless otherwise noted.
- Ainsworth
- Ainsworth Model LCB Chain balance Chain Gold (14 k?)
- Ainsworth Model LCB Chain balance beam Weight. 0.5000 g stainless steel: 0.540" long overall; center = 0.089" dia x 0.190 long; shoulders = 0.121" dia. Note that the beam has notches from 0 - 1.0 at 0.1 intervals along the beam, with 0 and 1.0 directly over the pan hangers.
- Ainsworth Model LCB Chain balance Stirrups with hooks.
- Ainsworth Model LCB Chain balance Magnetic Damper Vane.
- Two Ainsworth patents for chain balance mechanisms are provided in pdf format via the links below (the original patents, in pdf format, were kindly provided by Janet Van Doren, a retired analytical chemist).
- The flexible scale bearing the chain and associated elements, patent 2,022,306 (1932).
- The live-bearing for the chain on the beam, patent 2,111,842 (1937).
- Christian Becker
- Christian Becker Model AB-2 Chain balance beam Weight. 0.7172 g stainless steel. (Purchased in 1952. Weighed on a calibrated Mettler electronic analytical balance 11/9/99.) Note that with the dial reading chain balance from CB the notches do not go across the entire beam - they are offset for better visibility (see illustration in Christian Becker Analytical Balances) - thus the heavier weight than is seen in the Ainsworth balance above.
- Christian Becker Model AB-2 Chain balance Stirrup with hook. 2.9898 g aluminum body with polished flat agate bearing surface and brass hook assembly. (Purchased in 1952. Weighed on a calibrated Mettler electronic analytical balance 8/5/04.)The brass parts are of stamped sheet metal (0.032 in thick) with a laquered finish. The brass "U" appears to be press-fit into two holes through the aluminum stirrup body. The two arrest support screws are locked in place with small set screws. Comparison views vs. machinist's rule: Stirrup with hook; top view of stirrup body. Note that the pictures of the stirrup and hook assembly show the assembly upside down.
- Christian Becker Model SG-1 Specific Gravity Balance Weighing Chain. The chain + hanger = 1.2918 g, the hanger alone = 0.2953 g. (Balance purchased in 1950's, and still in use. Chain weighed on a calibrated Mettler electronic analytical balance 17 April 2000.)
- Voland
- Voland Analytical Balance Riders (5 & 10 mg) Aluminum wire. Note that the 10 mg riders are used on balances with a scale with 0 over the beam center, and 10 over the pan hanger; the 5 mg rider is used on balances with a scale going from 0 - 10 pan-hanger to pan-hanger, with 5 at the beam center-point.
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