To fit a new platform, first check that the replacement looks suitable. A new
unit is easily marked and subsequently too soiled to return for exchange.
If the pivot guard needs to be rotated to suit a contrate wheel to one
side, carefully remove the balance cock, complete with hairspring, balance wheel
etc. Put these very carefully to one side. Now very carefully remove the plate
holding the lever and escape wheel in place. With tweezers, lift out the lever
and escape wheel. To rotate the guard, hold the empty platform in one hand and
grip the guard in smooth jaw pliers. You can protect the jaws from marking the
surface with a little piece of card. Now very slowly rotate the guard to suit
the clock. If you turn it sharply it may shear off.
To fit the platform,
it is safer to remove the balance as described above. You will need the escape
wheel in place to establish the depth needed from the contrate wheel. A good way
to mark the hole positions is to fit some sharpened taper pins in the existing
holes. Fit the pins so that only 1mm or so protrudes. Place the platform in the
desired position and move slightly from side to side. The sharpened pins will
scratch the underside of the platform where the holes need to be drilled. Always
drill the holes slightly larger than the screws need. This will enable the
platform to be finally adjusted. The distance from the escape wheel pinion to
the contrate wheel is critical, and this final adjustment will have a noticeable
effect. Platform fixing washers cover up these holes and ensure that the special
screws used for platform fixing hold the platform firmly.
platform, being very careful to fit the pivots into their jewels before
tightening. Gently ease each pivot around it's jewel hole until it pops in. When
fe-fitting the balance wheel ensure that the jewel on the balance wheel is
between the forks of the lever. When the pivots of the balance wheel are
properly in their jewels, tighten up the screws. Never tighten up screws on a
platform if the pivots or staffs are not properly seated in their jewels. Just
the weight of the balance cock itself is enough to hold the balance in place.
Additional pressure will simply cause damage. The leverage effect of a screw
will bend a pivot of this size without you even knowing.
Repairing Your Own Clocks by Mervyn Passmore