End-shake — a wheel's axial play between its two jewels — is one of the most discreet and most decisive adjustments in a movement. Too little and the wheel binds; too much and the gearing shifts. Here is how to read and adjust it.
What end-shake really controls
A pivot must turn freely without moving significantly along its axis. End-shake ensures there is neither binding (friction, amplitude loss, stopping) nor float (teeth meshing too high or too low).
Indicative values
The acceptable values are those given in the manufacturer's data sheet.
How to check it
Under a stereo microscope, gently lift the wheel with fine tweezers while watching from the side: correct end-shake shows as a very slight vertical movement, perceptible but not “clacking”. On the balance, check with the cock fitted, moving the staff between upper and lower jewels.
Correcting: the staking tool and nothing else
Correction means moving the jewel or its setting in the plate or bridge, using a staking tool and the right punches: push the jewel a few hundredths, re-check, repeat. The gesture demands perfect punch centring — a jewel pushed at an angle cracks or splits, and the repair becomes a replacement. On screwed bridges with non-adjustable end-shake, correction means replacing the wheel or the jewel, not improvising.
Frequently asked questions
Can zero end-shake stop a watch?
Yes. A wheel pinched between its jewels rubs constantly: amplitude drops and the movement stops.
Can end-shake be corrected without a staking tool?
Not properly. Pushing a jewel by hand splits or decentres it. The staking tool guarantees the axis and the travel.
Want to practise checking play? Our reference tables and tool sheets support the diagnostic modules of the Décalibre curriculum.