Fitting stems and crowns
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CWR Technical Pages

Fitting stems and crowns

Popular crown styles

    The most common problem you will have when fitting stems is that the stem will be cut too short and rendered useless.  One good way to fit stems with a minimum of difficulty is to do the following.

1.   Remove old stem. 

2.   With movement in case, insert new stem. 

3.   If case is waterproof cut stem 1.5 mm from end of case tube; for dustproof cases, cut stem 1.5 mm from edge of case; for watches that use crowns with long posts, cut stem flush with case or tube. 

4.   Remove stem from watch. 

5.   Grip stem in notch with end-cutting pliers and screw crown onto stem tightly. 

6.   Replace stem into watch. 

7.   Measure the distance from the edge of the tube or case to the inside edge of the crown. 

8.   Remove the crown and cut the measured amount off from the stem minus about 0.25 mm to allow for stoning. 

9.   Stone down the end of the stem to make it flat and round over edges. 

10. Place a very small amount of LOC-TITE or Superglue on the end of the stem. 

11. If waterproof, place a small amount of silicone on case tube, then repeat steps 5 & 6 and you're done.

Fitting stems will take practice, but if you use this method you will have less problems.

There are some other things to consider when fitting new stems. Check the pilot hole and other bearing surfaces for excessive wear.  If worn excessively you will need to purchase or make a new oversized stem to correct the problem.

Things to consider when selecting proper crown: (1) color, (2) tap, (3) outside diameter, (4) inside diameter, (5) post length, (6) overall thickness, (7) design of watchcase.

Quartz watches generally use smaller crowns than mechanical watches.

Cut stem 1 mm from edge of case or tube

Use end cutting pliers to hold and cut stems

Fresh cut stem on left, stem with end finished on right

 

Finishing stem end using lathe and stone

Finishing stem end using pin vise and stone

 

 

 I made these pages as basic tech help to others in the horological field and to give the public an idea of what it takes to do even the smallest of repairs.  If anyone has any comments or something they would like to add to list, please eMail me.  Many minds working together will accomplish much more than one working alone.  Please note that there are many ways to do different things in horology and I am not implying that any ideas in these pages are the best or only way(s) to do any given project.

I will be adding pages to this list on a regular basis so be sure to check back often.

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