Wednesday, May 9, 2007

Chicago School Of Watchmaking Lesson 2

Master Watchmaking
A Modern, Complete, Practical Course
By Thomas B. Sweazey and Byron G. Sweazey.

The Chicago School of Watchmaking was founded in 1908 by Thomas b. Sweazey.


LESSON 2: CROWNS, STEMS, SLEEVES AND BOWS


There are two types of part assortments available: bulk assortments which are not separated. And pre-sorted assortments, which cost more, but are easier to use.

In American watches there are three types of setting arrangements:

The first is the pendant set which uses s stem and sleeve and sits inside the watchcase and is sometimes called a Negative Setting.

The second type of setting is called a Swiss setting and the stem is a part of the movement and is sometimes called a Positive Setting.

The third type of setting is called a lever set and it uses a set lever operated by the finger nail and is mostly used in railroad watches.

Section 49:
A sleeve is screwed inside the watchcase pendant. The top of the sleeve is threaded, as is the upper part of the pendant inside. The sleeve with the stem inside is screwed into the watchcase pendant with a sleeve wrench. The bottom of the sleeve is sectioned like four fingers, which grip the bottom of the stem in two places; the bottom notch for winding and the top notch for setting. The crown is screwed onto the top of the stem, which is threaded.

Section 42:
When removing a movement from a case which has full head screws, you need only remove the lower screw, loosen the top screw slightly, pull up the crown into the setting position and the movement will come out of the case.

Section 43:
To remove the crown from the stem, after the movement has been removed from the case, hold the winding square with a pair of flat nose pliers and turn the crown to the left with your right hand.

Section 44:
Sleeve wrenches have prongs with either two, or four lugs on the ends of the prongs. The wrench is placed inside the pendant of the watchcase to unscrew the sleeve. On some watches, the sleeve is old and cannot be removed with the sleeve wrench. In this case, remove the stem from the sleeve and use a square file, or broach to unscrew the sleeve from the pendant. Adjustments are done to the sleeve inside the pendant, with the stem still inside the sleeve.

Section 45:
Using the sleeve wrench, place the correct size prong inside the pendant and turn the wrench to the left and continue doing so until the sleeve is free of the pendant and case. the, remove the stem through the bottom of the sleeve.

Section 47:
When selecting a new sleeve, make sure the diameter of the threaded top is correct, that the threads are the correct pitch and that the length is correct.

Section 48:
If a thread breaks off inside the crown which is made of gold, rolled gold, gold plate, or nickle, soak the crown in a solution of water and alum to dissolve the steel thread.

Section 49:
When replacing the crown, make sure the threads fit the stem threads and fits over the pendant.

5 comments:

rrwatch said...

They forgot a couple of setting mechanisms used in some American movements.
The most common is key set, with examples of both front and back setting squares. The other is pin set, as found on the Model 1870 Waltham and, I believe, on a few others.

Paul Raposo said...

Thank you, rrwatch. I hope to post pics of all the types of setting mechanisms built. It is odd that the CSOW course would leave out key wind setting, considering that for years it was the American standard.

Also, thank you for leaving a comment. One of my goals with this blog, is for readers to share ideas and new information with each other. You've added new information to this post which will benefit us all.

Thanks and enjoy!

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