A watch press closes a snap-on case back by squeezing it evenly between a lower and upper die; a threaded or screw-fastened back needs a different tool entirely.
One wrong turn of the spindle can crack a crystal or distort a perfectly good case back. Closing a back with a press is quick, but only when you match the tool to the back type and let the dies do the work.
Which Case Backs Does a Press Actually Close?
A wrist watch press is designed for snap-on, press-fit backs that seat into a groove and pop into place under even pressure. It is the wrong tool for a screw-down back that threads into the case, and for a back held by small screws.
Inspect the outer edge first. A snap-on back has a narrow lip or retaining groove and usually a small pry notch; a screw-down back shows fine threads and often a wrench-flat pattern. If you see threads, a press will not seat it — it will just mash the gasket.
If the back is snap-on and you still need a press, the tested roundup of the best wrist watch press options covers budget and pro models side by side.
Preparing the Watch and Choosing Dies
Clean the case groove and back first — dust and old gasket residue prevent seating no matter how much pressure you apply. Confirm the gasket is present, flat in its channel, undamaged, and lightly greased with silicone grease if the watchmaker specifies it.
Then deal with clearance:
- Remove or move the bracelet. A trapped bracelet misaligns the load and can scratch the case.
- Support the case evenly. The lower die must carry the case without touching the crystal, crown, or pushers. A die slightly larger than the case is right; one that presses on the crystal will break it.
- Pick the upper die. It should contact only the outer perimeter of the back — never the center or any engraved or decorative surface. Nylon dies are standard because they will not mar the metal.
- Center everything. Beco’s Profi Press documentation specifies selecting pressure pieces by diameter and hole clearance, inserting them until they click, and checking that the workpiece sits centered and fully supported.
Die diameters matter more than the press. Too small concentrates force on the center of the back; too large catches the lugs or case edge and tilts the load. Either can deform the case or crack the crystal.
Closing the Back Step by Step
Start the back into the groove by hand, squarely, matching any notch or alignment mark. If it will not sit flat on its own, fix the alignment before pressing.
- Set the watch in the lower die with the case back facing up.
- Lower the upper die until it just touches the back’s outer rim.
- Turn the spindle slowly and evenly, watching the gap close all the way around.
- Stop as soon as the retaining lip seats. Beco’s instructions are explicit: stop when the component is securely seated and do not overtighten.
- Release the spindle and check the full circumference for even seating.
A correct close leaves the back flush with no visible gap or tilted edge, and the crown and pushers still move freely. If the back rocked or needed heavy force, back the spindle off and start again — a pinched gasket looks seated until the first splash of water.
Water Resistance and Common Mistakes
Closing a back does not restore water resistance. Any water-resistant watch that has been opened needs a pressure or vacuum test with proper equipment, and seals of uncertain age should be replaced at the same time.
The failures are predictable. Excessive force bends cases, distorts backs, and damages movements, so if the press needs real muscle, stop and check the gasket, groove, and die choice. Chipped or cracked crystals almost always trace back to a die that touched the glass. Incompatible or homemade dies are another repeat offender — use the pieces made for your press.
Watchmaker service documentation overrides any general procedure, including this one. When the manufacturer’s instructions conflict with a press manual, follow the manufacturer.
Common Questions
Can I close a screw-down case back with a press?
No. A screw-down back threads into the case and needs a case wrench or correct case-back tool turned by hand. A press applies straight downward force with no rotation, so it cannot engage threads and can crush the gasket or distort the back. Match the tool to the back type before applying pressure.
What happens if the die is the wrong size?
A die that is too small puts force on the center of the back or the crystal and can crack the glass or deform the metal. A die that is too large contacts the lugs or case edges, tilting the load and misaligning the back. The upper die should touch only the outer perimeter of the case back.
Do I need to test water resistance after closing the back?
Yes, if the watch is rated for water resistance. Closing the back seals nothing on its own — gasket condition and seating determine whether water stays out. A pressure or vacuum test with appropriate equipment confirms the seal, and any gasket of uncertain age should be replaced before that test.
Sources
- Grand Seiko. “9RB2 Instruction Manual” Manufacturer guidance on case handling and service procedures.
- Esslinger. “Case Closers Watch Back Tools” Product listings and specifications for watch case presses.
- Perrin Supply Ltd. “Case Presses” Catalog of case presses and die systems for watch work.