Opening a watch at home is perfectly doable, provided you use the right watchmaker tool and correctly identify the type of case-back. This guide walks through the three main systems and the tools they each call for.
Identify the case-back type
Three main families exist:
- Snap-back: held by pressure, found on 60% of consumer watches.
- Screw-back: unscrews with a pin wrench or a polygonal tool.
- Screw-down case-back: held by 4 or 6 screws around the rim.
Snap-back
Use a snap-back tool of the watchmaker-knife type. Slide the blade into the slot and lever gently.
- Place the watch on a case holder.
- Locate the side notch.
- Insert the tool and lever while keeping the blade parallel to the case.
Screw-back
Use a watchmaker key with 3 adjustable pins. Our screw-back tools cover the standard diameters.
Screw-down case-back
Check the screw size first (typically 1.2 to 1.6 mm). Pick the right driver from your set of watchmaker screwdrivers. Unscrew crosswise so the back doesn't warp.
| Case-back type | Main tool | Difficulty |
|---|---|---|
| Snap-back | Watchmaker knife | Easy |
| Screw-back | Pin wrench | Medium |
| Screw-down | Screwdriver 1.2-1.6 mm | Easy to medium |
Mistakes to avoid
- Opening a water-resistant watch without noting the back's orientation (you lose the gasket alignment).
- Forcing a screw-back: it's most likely a snap-back.
- Forgetting to replace the water-resistance gasket after opening.
« Before opening, identify. Before closing, check the gasket. »
FAQ
Can I safely open a water-resistant watch?
Yes, but you must replace the gasket after each opening and have water-resistance retested afterwards.
Which tool for a Rolex?
Screw-back Rolex models need a dedicated tool (Bergeon 5537 or equivalent). Don't try with a cheap universal key.
How do I know if my case-back is snap or screw?
Look for a side notch (snap-back) or pins/flutes on the rim (screw-back). Screw-down backs have visible screws.