Replacing balance staffs

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How balance staffsare replaced

• Ken Pell

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Components of balance assembly

• Wheel (split or solid)
• Staff (riveted or friction)
• Hairspring (flat or overcoil)
• Roller (single or double)

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Balance wheel
Roller
Hairspring
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Staff
Wheel
Roller and Jewel
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Hairspring Hub
Roller Hub
Wheel Hub
Pivot
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Why they must be replaced

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

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Broken Pivot
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Pre staffing

• Clean movement
• Examine and replace balance jewels
• Identify movement early and secure new staff

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Good Hole Jewel
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Cracked Hole Jewel
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Chipped hole jewel
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Selecting replacement staff

• Determine grade of watch
• Use Elgin reference for staff number
• Order staff
• Verify measurements

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Make a new staff?

• Not necessary 99 of time
• Need expertise on lathe
• Outsourcing is possible

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Take measurements

• Hairspring hub
• Roller hub
• Pivots

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Compare old to new
Pivot
Hairspring
Wheel
Roller
New Staff
Old staff
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Modify if needed

• Reduce diameter of hubs using lathe.
• Choose another staff

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Steps

• Remove hairspring
• Remove roller
• Remove balance wheel

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Mark the postion of the stud
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Mark Position Of collet
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Mark position Of roller jewel
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Remove wheel from staff

• Place staff in hole of table with wheel resting
  on the table.
• Push or tap staff out

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Wheel is resting On table
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Restaffing

• Place staff with roller side down in staking set.
• Choose appropriate round face and flat face
  punches.
• Place wheel over staff
• Rivet

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Rivet

• Use round face first, then flat
• Turn punch while tapping
• Always use brass hammer
• Test In lathe

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Replace roller

• Place on punch with hairspring side down
• Three quarter test
• Make sure jewel clears punch
• Tap or press on

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Roller sits 3/4th down
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