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Construction Features and Service Information Grade 911 22/0 Size Movemen

From American Horologist magazine, October 1938

Construction Features and Service Information
Grade 911 22/0 Size Movement

Exhaustive preliminary tests show that the new Hamilton Grade 911 is remarkably trouble free and an excellent timekeeper. Its cushion shape permits greater variety of case styling and there is every indication that this grade will be widely accepted.

Here again the principle of interchangeability applies and watchmakers will have no difficulty in fitting any necessary replacement parts.

To examine a Grade 911 movement, first remove the bezel. Then be sure to note the small slot in the cup between numerals six (6) and seven (7 )-as shown in Fig. 1. This slot is provided for removing the movement from the cup.  Due to the unusual position of the balance wheel in this movement serious damage may result if the watch-maker attempts to separate movement from the cup in the customary manner. Although the balance wheel is well protected by the shape of the pillar plate it is advisable to exercise extreme care in this operation.

General Specifications (Figure 2)
Plates and bridges of Grade 911 are of nickel silver with soft line finish, rhodium plated to provide a hard untarnishable surface. There are 17 ruby jewels. Except for the hair-spring, true interchangeability of parts is provided throughout the movement. The stem work is simple, sturdy, and dependable. The Elinvar hairspring is vibrated to a harder, more durable monometallic balance wheel. A unique method of utilizing the space in the movement permits the use of a large improved escapement. The winding wheel is supported accurately and rigidly by a large sturdy hub.

Hamilton Grade 911 employs the most modern system of friction jeweling.  The specially large hole jewels are inserted directly into the plates and bridges -a feature which permits the use of larger stronger jewels. Only highest quality friction jewels are used to insure accuracy and concentricity.

When replacing bar jewels it is recommended that the old jewels be removed by driving from the outside as illustrated in Figure 3.

The new jewel should be inserted from, the underside as illustrated In Figure 4.

Balance olive hole jewels should be driven out from the underside (figure 5) and replaced from the top side as shown in Figure 6, using a flat punch with a hole in the center slightly larger than the size of the hole in the jewel.  Careful measurements should be made so that the jewel is .02 mm. below flush with the balance endstone cap seat. See Figure 7.

If these instructions are followed, and genuine Hamilton material used, it will seldom if ever be found necessary to ream or modify the hole in any way.  In doing this work, a standard staking set or any of the special friction jeweling tools on the market can be" used.  In all cases where the finished side of the bridge is in contact with the stump as in Figures 4 and' 5, be sure to use a stump having a highly polished flat surface so as not to damage the finish.

For repair jobs where only the changing of a mainspring is required, it is not necessary to disturb the train bridge.  Simply remove the ratchet wheel and barrel bridge, and the barrel will lift out without any difficulty.

Cannon Pinion 
The Cannon pinion used in this movement is of the closed-end type (blind hole). Be sure when cleaning and reassembling the movement that this hole is perfectly clean.

Balance Staff 
When removing a broken balance staff from a balance wheel it is advisable to turn off the seat of the hub before driving out the staff. This procedure is described in Hamilton Technical Data Bulletins 11 7 and 119

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