Pulsynetic C6 & C7 master clock pendulum and bob.

Sometimes a Pulsynetic C7 master clock is obtained which lacks a pendulum. In the complete absence of factory spares and as a service to those faced with the construction of a completely new pendulum I offer the following images: The original flat rod would have been Invar with diagonal "scratches" [hatching?] to show its true heritage. The "bronze" finish on the bob was once popular on fireplaces and fittings.

The large rating nut could be turned to make coarse rating adjustments. Smaller changes to slow the clock's rate could be made by adding small weights to the top of the rating nut with tweezers. This avoided stopping the pendulum which often results in an erratic change of the original rate.

Weights could also be added to the top of the pendulum bob to speed up the clock's rate.

The threaded rating screw at the bottom of the pendulum rod is apparently a cycle thread. 5/16" x 26 TPI.

An ordinary, rear bicycle axle could no doubt provide the donor material and save the purchase of a special die to cut the thread on a bare rod.
A cycle wheel fixing nut would do at a pinch in the absence of an original.
The cast rating nut has the appearance of a water valve wheel. Here the underside is shown.

The rating nut now fitted but inverted when quickly posed for the photograph.

The slot in the Invar rod where the movement crutch pin fits. A slot provided freedom for vertical adjustment or change in position due to differential expansion without binding. Note the diagonal lines to indicate Invar rather than plain steel.
Invar is a nickel-steel alloy which has almost zero thermal expansion. Changes in temperature should not alter the rate of the clock.

A threaded crossbar [with large washers to trap the suspension spring] normally rests in the cast-in v-grooves in the Pulsynetic master clock movement.

The entire C6/C7 bob. Removing the small screws in the top plate will allow the inner weights to be fitted and removed for examination.

Click on any image for an enlargement.

No comments: