NOTES FROM THE BENCH
Clock Repair Archive - - Seth Thomas 124:
Regulation on the Seth Thomas 124:turn the regulator to the left for slower and turn
the regulator to the right to make the clock run faster. 1 turn = 2 1/2 minutes per
day.The seth thomas 124 must be checked at 12 and 1 o'clock because the hour snail
will force against the rack and the snail will sometimes be moved when the clock runs
down if the customer forces the hands ahead before the strike finishes lifting the rack.
The seth thomas 124 is a westminster chime mechanism with mainsprings wrapped
in barrels attached to the front plate (by rivets or screws). The gear teeth on this
mechanism are shaped slightly different than on most older clocks. The number 2 wheel
time , in my opinion , is the achilles heel of this clock. When overhauling one of these
pay very close attention to the brass gear; specifically the gear teeth . If these teeth
are worn it will be necessary to turn the wheel over or replace it. That is it.
This problem will have to be addressed, or the clock will not work. The clock will either
not keep time, or will stop inconsistently, or will exhibit both of these problems. Also
be prepared to turn the main wheels if the teeth are worn. The self correct lever on the
front plate must be absolutely free to drop. Do not get any oil behind this lever , or the
mechanism will not work. The oil will keep the lever from dropping freely.and the chime
sequence will not correct.
There are 2 small washers that fit on the movement posts on the bottom. The
purpose of these washers is to compensate for the thickness of the plate on the upper
part or the mechanism. Do not omit these washers; if they aren't there , they should be.
They need to be the same thickness as the top plate. The shutoff lever on the inside of
the plate will break if you try to bend it. Do not try to bend that lever; it is hard
brass. If that lever is broken , it will take a lot longer to fix than simply opening up
the plates and moving the gears until they are in the correct position .
The swing on the pendulum is normally quite excessive, an arc of 2 inches in
not uncommon. The pendulum is quite heavy (2 ¾ oz. usually). If the pendulum arc is
not within this parameter, it is very likely that there are problems that haven't been
discovered. On this mechanism , the depth of the gears in the time train is critical ,
partially because there is one extra gear at compared to other 8 day westminster chime
clocks,and partially because the mainspring is not of excessive strength. The pivots on
these clocks are not plated and the bushings tend to be prone to wear.
The hammers will tend to bounce on most of these mechanisms. Somewhat
thick grease (mainspring lube, for example) will help some. Trial and error adjustment
of the hammers will also help. Most of the 124 mechanisms have a chime/silent device,
that lifts the first 4 hammers so no chime sounds but there will be gear noise, and the
strike will still sound in most cases.
Be sure to check the strike trip lever that is activated by the large pin on the
front of the chime sequence cam. It should lift the strike lock lever enough to clear the
rack and allow the rack to fall and the 5th wheel the rotate HALFWAY around to the
lock lever which should get enough travel so that the strike hammer waits long enough
to allow for the strike to sound like a separate sequence from the chime. Total
suspension length is 3.970 inches. Another suspension was measured that was .004 inches
strong by .186 inches wide with a suspension wire diameter of .075 inches. Total
suspension length is 3.970 inches .
The mainsprings on these measure : chime: .750 inches wide by 72 inches
long by .015 inches strong ; strike : .014 inches strong by .687 inches wide by 53
inches long ; time .014 inches strong by .687 inches wide by 75 inches long.
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