Seth Thomas round top in for servicing -Part I

This is a Seth Thomas round top mantel clock in for servicing. This is Part I of two parts.

Among the most respected American clockmakers is the Seth Thomas Clock Co. My collection consists of six Seth Thomas clocks representing several styles made between 1865 and 1930.

Seth Thomas time and strike 8-day alarm clock

I purchased this particular mantel clock at the National Association of Watch and Clock Collectors conference in Springfield Ma. in June of 2019.

I completed a minor veneer repair on the case and installed a new spring for the alarm mechanism shortly after I got the clock. Attending to the movement is the final step.

Veneer repair between 9 and 11 on the access door
New alarm spring

It is a fairly large round top shelf clock measuring 15 inches in height, 10 inches wide at the base and 4 inches deep. The attractive Rosewood veneered case has a mirrored rectangular lower tablet. The grain is bold, nicely textured and immediately catches the eye in any room.

Movement seems to be stuffed into the case.

A distinctive feature is the sturdy, well designed lyre 8-day “Plymouth” time and strike spring-driven movement on a bell gong with alarm so called because it was made in Plymouth Conn. Plymouth Hollow, Connecticut became the town of Thomaston in 1865. Seth Thomas would have used movements with the Plymouth stamp through to the 1870s and this clock is probably from the 1865-70 period.

The movement is fitted with Geneva stops (stop-works) to improve timekeeping. Instead of the usual star wheel with one long point attached to the mainspring arbour the stops on this movement have a cam wheel with one long point.

Time and strike movement

The large movement fit into a relatively snug space. There are factory cut oil cups for the front bushings but not the rear.

Both the alarm and the movement strike on an iron bell gong.

The movement is mounted on the rear of the case by means of woodblocks top and bottom. To remove the movement from its case the rear panel must be unscrewed from the case.

Most clocks have 4 pillars. This has 5 pillars with an odd arrangement. Aside from the three corner pillars, there is a pillar near the escape wheel and one located in the centre of the movement which I assume are there to provide strength and to mitigate torque twisting from the powerful mainsprings.

The plates are held together with soft steel wires rather than screws or taper pins which I do not often find on an old movement. The wires are wrapped around each pillar and they are a challenge to remove. The wire wrapped around the escape wheel pillar is particularly awkward to remove. The mainspring arbours have similar wire retainers halfway up the pillar to prevent creeping.

While in the process of removing the wires that held the plates I discovered that I need better quality needle nose pliers.

Wires through the anchor pillars

My observations:

  • Two bent teeth on the count wheel. (Straightened with smooth nose pliers).
  • The fan on the flywheel was disconnected from the arbour. (Tightened and adjusted to achieve minimum slippage. Some slippage is necessary when the strike comes to an abrupt stop.)
  • Tool marks on the lifting lever to synchronize the hour hand with the strike.  Aside from two other levers that look like they were slightly bent, there are no other tool marks anywhere on the movement. (lever adjustments like these can be made without dismantling the movement).
  • S2 lantern pinion with one wire protruding from the lantern pinion assembly. It seemed odd until I discovered why. The wire could have caused the bent teeth and was replaced.
  • 4 bushings; S3F, T3R, T4R (escape wheel), hour wheel, front. Fewer than expected.
  • No helper springs and none required.
The arrow shows wire protruding from lantern assembly

During my inspection, I discovered a protruding wire on a lantern pinion. Is it supposed to be there? If so, is the location critical? Yes to both. The count wheel must advance correctly in relation to the maintenance cam.

This movement has not had much running over the years and aside from adjustments made without dis-assembly and occasional oiling it has never been serviced.

Join me in Part II when I go over bushing work, cleaning, final assembly and testing.