How balance staffs are replaced Ken Pell

How balance staffs are replaced

• Ken Pell

Components of balance assembly

• Wheel (split or solid)

• Staff (riveted or friction)

• Hairspring (flat or overcoil)

• Roller (single or double)

Why they must be replaced

• Trauma, such as dropping or bumping watch which damages the staff and jewels

Pre staffing

• Clean movement

• Examine and replace balance jewels

• Identify movement early and secure new staff

Selecting replacement staff

• Determine grade of watch

• Use Elgin reference for staff number

• Order staff

• Verify measurements

Make a new staff?

• Not necessary 99% of time

• Need expertise on lathe

• Outsourcing is possible

Take measurements

• Hairspring hub

• Roller hub

• Pivots

Compare old to new

Modify if needed

• Reduce diameter of hubs using lathe.

• Choose another staff

Steps

• Remove hairspring

• Remove roller

• Remove balance wheel

Remove wheel from staff

• Place staff in hole of table with wheel resting on the table.

• Push or tap staff out

Restaffing

• Place staff with roller side down in staking set.

• Choose appropriate round face and flat face punches.

• Place wheel over staff

• Rivet

Rivet

• Use round face first, then flat

• Turn punch while tapping

• Always use brass hammer

• Test In lathe

Replace roller

• Place on punch with hairspring side down

• “Three quarter” test

• Make sure jewel clears punch

• Tap or press on