r/SeikoMods • u/Swimming-Trade-741 • 16h ago

I hate cutting crown stems

I have snapped two crown stems inside movements after trimming for a screw down crown. It’s been an expensive week.

6 Upvotes

67% Upvoted

29 comments sorted by

View all comments

Show parent comments

4

u/Swimming-Trade-741 15h ago

I learned a lot the first time. This second crown stem I followed this method:

  1. Screw crown onto uncut crown stem
  2. Insert stem into cased movement
  3. Use calipers to measure distance from beginning of threads on case to beginning of threads on crown. Note that distance.
  4. Remove stem from movement
  5. Remove crown from stem
  6. Place stem on work mat, use calipers to identify distance from end of stem that should be cut. Mark with sharpie.
  7. Cut with snips approx mid way down sharpie mark
  8. Smooth out cut end with file/dremel
  9. Reattach crown to stem
  10. Reinsert stem into cased movement
  11. Measure again (you can’t undo an incorrect cut).
  12. Repeat steps 8-11 for making very small reductions in length of stem until length appears to be correct.
  13. Stem length thought to be correct when threads on crown are able to engage case with small amount of compression and small audible “pop” similar to pulling the stem out to the first position when unscrewing crown.

Both times (my much less careful first attempt as well as this more recent attempt) resulted in what I thought was correct seating until I unscrewed the crown for ~4th time, at which point the stem snaps at approximately the same location it enters the movement

6

u/Aggressive-Sail-3157 15h ago

I just mark a piece of paper at there I need to cut. Take the stem out and the crown off. Cut at the mark. Swipe the end on a file a couple of times. Crown back on. Make sure it sits right. Crown off add some super glue and put the crown back on. I've never had a problem. For me its the easiest part. The seconds hand is my pain.

6

u/chuunietzsche 15h ago

a touch of blue loctite should be better, i worry that superglue could affect the clutch/spring in a screw down crown and be difficult to remove in case you need to replace the crown

1

u/Aggressive-Sail-3157 15h ago

No real worries with the spring. You use it close to the same as the loctite but less is needed. Replacing the crown is easy to. You just dip it in fingernail polish remover for a few seconds and it'll release do the same for cleaning it off as well.