The end of the suspension is all that remains of the pendulum

Clock Repair 101: Ordering replacement parts

In my previous post I calculated the theoretical length of the pendulum my Korean 30-day clock requires. You may recall that the clock as I bought it had a broken pendulum suspension spring, and the pendulum parts – the suspension rod and bob – were missing. In this post I order replacement pendulum parts.

Now that I’ve searched for antique clocks here and there, I’ve found that a number of clocks for sale As-Is have no pendulum bob. Looking at eBay listings, I suspect it’s because the seller can sell the clock in parts (bob, case, works) for a higher price than the whole clock.

Pendulum parts can also be broken and tossed out: the delicate spring at the top of the pendulum suspension rod is easily broken. I suspect that’s what happened to my clock.

Parts can be lost in the process of donating an old clock to a thrift store: the person getting rid of the clock may not take care in packaging the pendulum parts (and the key) with the clock.

For all these reasons, it’s a good idea to find a supplier of replacement pendulum parts. I’m happy with; others like Merritts,, ClockWorks, or others.

The new, replacement suspension rod and bob
The new, replacement suspension rod and bob

I was delighted to find Timesavers carries a suspension rod that sounded like a simple replacement: “Korean 31-Day Suspension Rod”. But I was puzzled by the length: it’s listed as 12 inches long, and my calculation of pendulum length was a lot shorter. Eventually I realized that the shipped suspension rod is designed to be too long so that I can cut it and add a hook at just the right length. I bought 2 rods just in case I mess up the first one. I’ll be cutting that rod once I have the clock running again.

The pendulum bob was a little trickier to choose. There are a bewildering number of bobs to choose from. I narrowed it down to a smooth, brass bob with a “rating nut” (fine height/speed adjustment), and a loop at the top. Then I simply picked a bob that looked the right size: “2-1/4″ Brass Adjustable Bob”. Once I put the works back in the case, we’ll find whether I made the right choice.

Incidentally, I also bought a new winding key to replace the missing one: “#7 Extra Large Wing Single End Key-3.8mm”.

In my next post about this clock I cut the pendulum to the correct length, and adjust the clock to the correct speed.