STEM / WINDING GEAR LUBE
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STEM / WINDING GEAR LUBE
Crown and stem identification Tap sizes and the measurements that match crowns and stems to a movement.
Crown and stem identification
How to identify the crown or winding stem a repair needs: thread and tap sizes, the measurements that matter, and how to match the two parts to each other.
Tap sizes
Stems and crowns join by a threaded end, and suppliers describe the thread by its tap size. Measure the diameter of the threaded end of the stem with a caliper and match it against a tap-size chart. Published conversions differ slightly between sources, so where the fit matters, match the stem and crown physically or order both from the same system.
Measuring a crown
Record the outside diameter across the crown, the length of the tube and thread, and whether the crown screws down and needs a gasket. For screw-down crowns, the gasket groove is part of the fit.
Measuring a stem
Record the overall length, the diameter of the threaded end, and the size of the square section that engages the movement's setting mechanism. Stems are commonly cut to length during fitting.
Find the stem for a movement
The movement spec tables on our product pages list the stem part number for each movement we stock. Kits and refills carry the common sizes.