This is an unusual 8-day endless chain tall case clock.

Unusual in that most endless chain / rope clocks are 30 hour movements.

The movement looks to have been handmade and not manufactured professionally. The construction is similar to a Morbier movement except, in this case, both time and strike trains are lined up one behind the other. This enables them each to use the same chain to power both trains. As such, there is only one weight used on one continuous chain.

The clock’s case is exceptionally robust, made of solid oak and weighs as much as it looks.

I purchased this clock without the weight or the pendulum. The challenge was to figure out pendulum length and weight. This has not proved an easy puzzle to solve. I wanted to maintain the aesthetic of the original design and have the pendulum bob sitting in line with the peephole window set in the center of the case trunk.

There are formulas one can use to calculate pendulum length; the easiest is to count teeth on the wheels and use the following tool:

http://www.horologysource.com/CalcPendulumLength.htm

However, because this is an unconventional clock, with unconventional gear ratios (remember it is 8-day, when one would assume it is 30-hour), the formula didn’t work in this case. So, plan B.

When you take into account all the variables such as pendulum length, weight, pallet adjustment (which affects pendulum swing), optimum beat, and the weights used to power the clock, there is an infinite number of possibilities one could end up using to get the correct set-up.

I personally started by fine tuning the pallet adjustment and then I was able to get the clock in beat. At that point, I could (by trial and error) determine the correct weight to use. I like to use the least heavy weight I can get away with; in this case it was a 10lb weight.

After establishing those factors, it is then a matter of getting the correct pendulum length and bob weight. I am still working furiously to determine these specs. Trial and error. Trial and error. I am getting closer, but the challenge continues.