Ansonia Drop Extra does not run and a rusty mainspring is the culprit

Ansonia Extra Drop time-only wall clock

Some time ago I wrote an article on an interesting acquisition, an Ansonia Extra Drop, a true barn find.

This Ansonia Extra Drop time-only Rosewood veneered wall clock was manufactured in the early 1880s by what was then known as the Ansonia Brass and Copper Company.

It was in pretty rough shape when I bought it and the only significant part missing is the brass dial bezel and a number of minor items such as the verge, hands, pendulum bob, suspension spring/rod, and the drop access door (which I made later on).

I was challenged by the whole prospect of putting the many pieces back together and giving what most would consider a throw-away movement, a second chance.

Siezed time-only movement
A sad-looking and seized time-only movement

Here is the movement when I found it. What a sight! I thought if I stripped away all the rust and dirt something of value would be salvageable. How many of you would simply toss it out?

After disassembly, scrubbing, cleaning, and one new escape wheel bushing here is the final result.

Cleaned up time only movement
Cleaned and serviced time only movement

First servicing

The fact that the spring was unwound on the movement when I received it tells me two things. One, the chance that it is “set” is reduced and secondly, having an open coil means more surface rust on the outer part of the spring.

I did my best to remove most of the rust on the mainspring and it went back in the movement. A short while later I discovered that the clock would only run if I wound it about halfway. Otherwise, if wound tight it would not run at all. The surface rust was evidently causing it to stop.

Some clockmakers who after observing any rust on a mainspring would immediately toss it out and argue that the spring is weaker because of the presence of surface rust. In this case, the mainspring is unsightly but has no cracks and has plenty of power.

Other repairers apply a liquid or gel, black tea, or even use electrolytic rust removal to extricate the rust. I know I risk igniting a debate about mainspring replacement and if I were in the business of clock repair, I would certainly toss out the mainspring and pass the cost on to the customer. However, I am hesitant to spend money on a new mainspring for what is essentially a $5.00 barn-find clock and my challenge was to spend as little money as possible on this clock.

During the initial servicing, I managed to get rid of most of the mainspring rust.

Second servicing

Still some problems. After several months I took it apart again, ran the parts through my new ultrasonic cleaner which I did not have at the time of the first servicing. I placed the mainspring in as well. Scotch Brite abrasive pad and WD40 combined are excellent for cleaning a mainspring and I was able to effectively smooth out the rough and rusty outer sections of the mainspring. Again, I checked for cracks and suspicious imperfections and found none. After rubbing the abrasive pad over the mainspring several times I gave it a healthy coating of Keystone mainspring oil. A smoother, rust-free mainspring should function a lot better.

Rather than mount the movement on the test stand, I installed it back into its case but left the dial off so I could monitor it more closely. It runs very well and has run several full 8-day cycles.

Ansonia movement in case
Ansonia movement in its case

I realize that I have pushed the limit of this mainspring and the next step is a replacement but we’ll see what happens after the testing period.

Weeks later

The movement continues to run well and now it is time to put everything back together.