mainspring servicing – Antique and Vintage Mechanical Clocks

In a previous article on servicing this clock, I mentioned the challenge I faced with the mainspring. With only minimal tools at my disposal and no spring winder, I was determined to find a solution and successfully service the mainspring.

This clock was manufactured by New Haven and boasts a classic design with a twelve-inch Roman Numeral dial and a distinctive short drop style.

The softwood case is veneered in Rosewood veneer accents. The clock’s case must have been quite elegant at one time, but now it is showing much wear and tear.

Given the condition of the case, I anticipated that the movement would be just as well-worn. It was in better condition than I thought.

Let me point out that the servicing is being done under less-than-ideal conditions. I am at our summer cottage with only the basic tools for clock repair, so I must either improvise or skip certain procedures.

No spring winder | no problem

The movement had already been restrained with a heavy copper wire.

_{A heavy copper wire contains the mainspring}

First, partially reassemble the movement with only the main wheel and second wheels. Reattach the front plate and secure the movement with the 4 pillar nuts.

Attaching the second wheel allows the main wheel to be stabilized while the spring is wound using the ratchet.

Safety first

I strongly recommend wearing leather work gloves and eye protection. Handling mainsprings under tension can be hazardous, so prioritizing safety is crucial. Precautions are essential to protect yourself from potential injuries.

Next steps

The key is to hold onto the second wheel while winding the clock. Once fully wound the copper restraining wire can be removed. In the photo below the screwdriver is arresting the wheel while I take the photo.

Then, using a letdown tool, release the click by popping out the click spring from the rachet and allowing the mainspring to unwind. The main wheel with the relaxed spring can now be safely removed from the movement.

Servicing involves carefully removing the main wheel from the spring, manually inspecting and cleaning the spring, re-oiling it, and reconnecting it with the main wheel.

_{The mainspring is removed from the main wheel for cleaning}

Reassembly

After cleaning the main wheel and the spring, simply reverse the procedure. Reattach the click spring, join the main wheel and the mainspring, place them back in the movement along with the second wheel, wind the spring, and secure it again with the copper restraining wire. Once this is done, you can continue to reassemble the movement.

May not be suitable for all applications

This approach allows the main wheel to be cleaned in the ultrasonic cleaner along with all the other movement parts.

While this method may not be suitable for all open mainspring designs, it might be the solution for you.

Servicing a mainspring without a spring winder isn’t ideal, it can still be done safely and effectively.

Servicing this movement is reminiscent of days gone by when Dad (or Mom) would gather tools from the shed to fix the family clock. The repair might not have been perfect, but the goal was always to keep the clock running reliably until the next time it needed attention.

One more shot is what it deserves. It had been running fairly well since I serviced it three years ago it but in the last few weeks it has decided to run for about 5 minutes and stop and I think I know the reason why.

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.

The brass dial bezel is the only significant part missing. Minor items such as the verge, hands, pendulum bob, suspension spring/rod, and the drop access door were easily sourced. I made the drop access door later on.

Here is an article I wrote in 2018 wherein I assess the case and movement for the first time. At the time I was challenged by the prospect of putting a rusty old movement back in running condition and giving it a new life.

It was in poor condition when I bought since it literally came out of a barn and it is just pure luck that it runs at all.

The symptoms? If wound halfway it would run 3-4 days and stop. If wound tight it would not run at all because surface rust and other contaminants caused the coils to bind together. This is very typical of old clocks that have not been running for years. A movement that is “overwound” is a myth. It is the combination of old oil, rust and dirt that seizes the mainspring.

Rusty mainsprings

For some clockmakers any rust on a mainspring means that is it tossed it out because the mainspring is inherently weaker. This particular mainspring has surface rust on the outer two coils and rust on the edges of the spring. Otherwise, it has no cracks or splits and has plenty of power.

Generally, to remove rust, repairers often apply a liquid gel, black tea, or even use electrolytic rust removal.

If I were in the business of clock repair, I would certainly replace the mainspring and pass the cost on to the customer. However, the original mainspring is part of the history of the clock and I don’t think the amount of rust is enough to prevent me from reusing as long as it is cleaned properly. As far as I am concerned, replacing a mainspring is the last resort.

Servicing yet again

Now that I have it apart why not throw the parts into the ultrasonic for a good cleaning. After everything was dry I inspected the parts, polished the pivots, and pegged the pivot holes.

I released the mainspring but this is how it came out of the case

I gave special attention to the mainspring. After inspecting it (yet again) I used a Brillo pad, steel wool and a microfiber cloth to eliminate the roughness as much as possible.

Ansonia mainspring cleaned up and ready for installation

Following the cleaning I applied a thin film of Keystone mainspring oil. I then reassembled the movement and oiled it prior to placing it on the test stand.

While on the stand I gave the mainspring a few turns, put the movement in beat and it ran well for a couple of days which is what I expected.

On day 4, it was time for the ultimate test, to wind it fully till it winds no further. I was hoping for a good result and it ran the full 8-day cycle. The mainspring just might be “clean” enough that it will now run without stopping.

I will monitor the results of this little experiment for a while longer but for now things very good.

Another mainspring saved from the recycle bin.

Tag: mainspring servicing

How to Service an Open Mainspring Without a Spring Winder – Step-by-Step Guide

I am very close to replacing the mainspring on a Ansonia time-only movement

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