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Technical Data: Hamilton Balance Staffs

Technical Data
Hamilton Watch Company
Lancaster, Pennsylvania

Subject: Balance Staffs

THE Hamilton Watch Company has from time to time found it necessary to make changes in the style and the dimensions of Hamilton balance staffs, due to new watch designs and improvements in the method of manufacture. These changes may sometimes make it difficult to obtain the correct balance staff immediately. This data sheet has been prepared. in order to help the watch repairman distinguish these changes with the greatest possible ease.  Be sure you obtain genuine staffs. They have the correct measurements making alterations unnecessary and cut down the time needed to fit new staffs into the watches.

ALL genuine Hamilton balance pivots are burnished by a new and improved method. No abrasives are used to burnish the pivot after the staff has been finished to size.  A pivot manufactured in this way is superior to one produced by other methods as the burnishing has a tendency to work harden the pivot. The pores in the steel are closed to a great extent by work-hardening and thus a hard outer case is formed around the pivot. This burnishing makes the pivots smoother and better able to withstand wear. Staffs finished by this method have little tendency to pit endstones.

IT is commonl y known that pivots polished with abrasive compounds retain some of the polishing material in the pores of the steel. When these pivots are running in oiled jewels, the oil mixing with the abrasives makes an excellent cutting compound, with the result that a hole is drilled in the endstone. All jewels used. in Hamilton Watches are of the finest quality Rubies and -Sapphires.  With all the hardness of these jewels, if the balance pivots are not perfect, the jewels will pit and wear. It must be remembered the balance wheel oscillates 157,680,000 times yearly and it stands to reason that an imperfect staff due to this rapid motion is apt to damage the jewel in which it runs. 


18-S staffs, both double and single roller types were made with large and small collet shoulders. In the illustrations, S. R. and D. R. mean single roller and double roller. L. C. and S. C. signify large and small collet shoulders.
In watches numbered over 100,000 only staffs having small collet shoulders were used. Watches with numbers under 100,000 may have used staffs wiLh either large or small collet shoulders. 

16-S staffs were made with large and small collet shoulders. Some watches numbered under 100;000 used staffs with large collet shoulders, others used staffs with small collet shoulders. Watches numbered over 100,000 used staffs with small collet shoulders. 
12-S staffs, in watches of grades 920, 900, 914, 910 with numbers under 1902601 used 5, R. type staffs, (Catalogue No, 1250). Watches of these grades, numbered from 1902601-700, used the D, R. staffs, (Catalogue No, 1250A), 
In watches from 1902701 - 800 the S. R. type staffs were used, (Catalogue No, 1250).
In watches from 1902801 D. R. type staffs, (Catalogue No. 1250A), were used.
12-S staffs in watches of grades 922, 904, 902, 918, 916, 912 are D. R. type, (Catalogue No, 3050). 

6/0-S staffs in Watches Grade 986 were both single roller and double roller. Watches Grade 986 before No. 2041401 used staffs, Catalogue No. 1927. Watches Grade 986 after No. 2041400 used staffs, Catalogue No. 1927A. 
It is necessary to give full description and catalogue number of material desired. The Material Sales Department of the Hamilton Watch Co., suggest, whenever possible, sending the part to be duplicated, with orders for material. By doing this, you will insure yourself prompt and accurate service. Your co-operation will be greatly appreciated by this department. 
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