Preparation of Steel to Make a Balance Staff

From The American Horologist magazine, January 1942

Preparation of Steel to Make a Balance Staff

1. Hardening Steel - Select a suitable piece of soft drill rod or stub steel for the job in hand. Wrap binding wire five or six times around it and leave about a four or five inch length of wire to hold in fingers. Cover with soap and heat to a cherry-red color or slightly more. Plunge in cold water, end first. It should now be white in color. Clean off the scaling to a polish with emery cloth or sticks.


2. Annelling Steel - To annel use a material lid or box and roll the steel back and forth watching the color very carefully. When it becomes a dark blue with a little tinge of purple, drop it into water or benzine to stop further annelling.


3. VERY IMPORTANT - To check on No. 1 and No. 2 to be sure steel is suitable for staff - Now turn a conical pivot on one end with the graver auot a .14 or .15 m/m pivot. Using pivot straightening tweezers, bend the pivot off center, now straighten. Bend it again and straighten. Now bend it a third time and at the next try at straightening it should break off. If the pivot breaks on the first or second attempt clean the blue off again and reblue it to a dark blue and try again to bend and straighten.  Steel prepared as above will be soft enough to turn nicely, hard enough to polish well, and hard enough to give good service in the watch.