So you want to fix a mechanical clock – Part I – a beginner’s toolkit

Tools are essential for clock repair because they enable precision and accuracy, which are critical when working with delicate mechanisms and intricate components. Let’s identify the key reasons.

Antique and vintage clocks can lose significant value if repaired improperly. Using the right tools minimizes the risk of damage, preserving their historical and monetary worth. The right tools, such as screwdrivers, pliers, and tweezers, allow you to handle small parts without causing damage. Specialized tools ensure components are handled carefully and correctly.

Proper tools make the repair process faster and more straightforward. For beginners, having the right tools helps build confidence and competence. They allow you to focus on understanding clock mechanisms without being hindered by improper equipment.

This article will describe some of the tools required to tackle the repair and/or cleaning of mechanical clocks.

Based on years of clock repair experience, I recommend the following essential tools for any beginner’s toolkit. While some of these tools can be sourced from your local hardware store, specialty items will need to be ordered from clock supply companies such as Timesavers (USA), Perrin (Canada), or Meadows and Passmore (UK).

Whenever possible, avoid purchasing tools from craft shops, as their prices are often significantly higher. They are ideal for paint and quality paintbrushes but they tend to charge much higher prices for general-purpose tools. A ball peen hammer bought at a hardware store, for instance, costs half as much as one found in a craft shop.

A suggested list of items

Keys: clock keys come in many different sizes. You must use the correct key for the winding arbours of your clock. The pronged keys in the photo below will fit a multitude of arbours.

Magnifier: They are available in various strengths and allow a much closer view of your work.

Work light: Illuminates your work, this one articulates and has a magnifier. I have since replaced this light with an LED one. The lamp burnt out and the cost of the fluorescent lamp was more than the entire lamp. Plus the new LED lamp has light temperature and intensity controls.

Pliers: A variety of pliers to hold onto your work, release taper pins, tighten nuts, and cut wires. The green handle pliers are non-serrated (flat-nose).

Hammers: A ball peen hammer is very useful (not pictured). The craft clip holder is useful for steadying items that are to be soldered.

Files: Variety of sizes to help shape or file down anything on a movement. Avoid inexpensive Chinses files and spend a little more on quality ones.

Tweezers: Getting into tight situations, grabbing small parts, and positioning parts into place are typical uses for tweezers

Level: To find the correct beat the movement (clock) must be level.

Spring clamps: To restrain the power of the mainspring. The flat clamp (upper right) is for those mainsprings which do not leave a lot of working room. Otherwise, the other round clamps are good for most applications. I prefer the flat clamps.

Screwdrivers: Always handy to remove movements from cases, loosen bolts, and pry parts.

Letdown set: Before working on a movement the mainsprings must be let down or restrained in their clamps. The letdown key is the safest method of letting down the mainsprings. Inserts cover most arbour sizes.

Hand reamers and broaches (cutting and smoothing): For bushing clocks when you cannot afford the luxury of a bushing machine. Cutting and smoothing broaches are useful for enlarging a new bushing when tight tolerances are required. They come in assorted sizes.

Cotton swabs: A variety of cleaning uses.

Clock oil: Once the movement is apart and cleaned it must be re-assembled and then oiled before use. The oil, whether it is conventional or synthetic, must be specifically designed for a clock movement.

Toothpicks: For cleaning and “pegging out” bushings on a movement

Clock stand: Once the movement has been re-assembled it is tested outside the case for a short period. Gene’s movement stand is a fully adjustable test stand.

Clock movement stand — _{Gene’s clock movement stand}

For those handy with a hammer and saw a stand can be made at home with whatever lumber is at hand.

Testing the Kienzle movement on a makeshift test stand — _{Testing a movement on a home-built test stand}

Camera: At every part of the process a digital camera can record critical stages in assembling and disassembling a movement. I use a 50mm macro lens for close work. A cellphone is a perfectly acceptable alternative but one with good macro capabilities is preferred.

Electronic Caliper: Indispensable for measuring the thickness of anything be it springs, pivots, plates, and so on. Available at a clock supply house or save a little money and buy the same tool from a retail outlet such as Canadian Tire in Canada.

_{Using a micrometer to check pivot diameter}

Pivot locator: It is an excellent tool for aligning pivots with their holes during assembly.

Build your set of tools little by little to spread the cost. You may already have some of the items I’ve mentioned but buy what you need when you need it. As for those specialized tools, broaches for example, it pays to spend a little extra for better quality.

These are the tools you require to start your journey into clock repair. If you have a tool (or tools) you feel is indispensable for the beginning clock-maker please let me know.

In Part II I will describe tools for those who would wish to advance their skills in clock repair.

October 29, 2017

Clock key sizes – do you have the right one?

Winding arbors on a Seth Thomas mantel clock (arrows)

Understanding the role of the clock key is essential for proper clock maintenance and operation. The clock key not only winds your antique or vintage clock but also plays a crucial part in ensuring it runs smoothly and efficiently. However, using the correct size key is just as important as the key itself. Using the wrong size can lead to damage or improper winding, affecting the longevity and performance of your clock.

In this article, we’ll explore the purpose of the clock key, why choosing the right size is vital, and provide a helpful chart to guide you in selecting the correct key for your clock.

Winding Mechanical clocks

Mechanical clocks require periodic winding. Some clocks need to be wound daily, such as 30-hour clocks, while others are wound once a week (8-day clocks). Some clocks run for 14 days, and anniversary clocks can run for up to 400 days on a single winding.

Most mechanical clocks have a winding hole located on the dial face, where the clock key is inserted. The key should fit snugly—neither too tight nor too loose—ensuring smooth operation when winding.

Why Key Size Matters

Except for the smaller regulating arbour on some clock faces, most winding arbours or winding points are the same size on the clock. This means one key will fit all of them. However, over time, a clock’s original key may go missing. If this happens, you can often use a key from another mechanical clock, and one of them will usually fit.

A micrometre is a useful tool to measure the thickness of a winding arbour. However, measuring the arbour’s size often requires removing the clock movement from its case. Once you’ve measured, you can order the correct key online.

Different Types of Keys

In general, larger German movements use a #8 key, though some require a #7 key. Many 31-day clocks, or clocks made in Korea or China, use a #6 or #7 key. Many American mantel clocks require a #5 or #6 key.

Keys come in all shapes and sizes. In the photo below are keys from German and American movements. The two-pronged keys (4 and 5 prongs) are available at any clock supply house such as Perrin or Timesavers and will fit many clock winding arbours. Many other sizes can also be ordered. eBay, online marketplaces and antique stores are other sources for clock keys.

In the photo below you can see two types of double-ended keys

The one on the left is used for winding a typical American clock. The large end fits into the winding arbour while the small end is for adjusting the speed of your clock. Many clocks have a smaller arbour used for adjusting the speed of your clock and will have “S” and “F” (Slow/Fast) inscribed on the dial generally near the 12 o’clock position.

The key on the right is for a time-only carriage clock. The small end is used to advance the minute hand and the large end fits onto the mainspring arbour.

Speed adjustment arbor — _{Speed adjustment arbour requires the small end of a two-ended key}

Grandfather and Ogee Clocks

30-hour weight-driven Ogee clocks typically require a #4, #5, or #6 crank key. Many grandfather clocks use a #10 or #11 winding crank, and it’s important not to wind them with a conventional clock key. For clocks with weight cables, the winding crank is essential for raising the weights. Insert the crank into the arbour and carefully wind the weights up until they reach the top of the clock, ensuring they remain fully visible.

Some clock keys will also have a number stamped on them indicating their size.

Storing Your Clock Key

It’s important to keep your clock key in a safe, easily accessible place. Keys should be stored either beside the clock, within the front access door of a wall clock, or in a caddy inside the case. Mantel clocks with key caddies can be inconvenient, as you must move the clock to open the back door to access the key. However, for homes with small children, keeping the key in its caddy helps ensure it remains out of reach.

Key caddy behind access door — _{Key caddy behind the access door}

Key Size Chart

Here is a chart that lists key sizes in millimetres for both American and Swiss movements, from small to large:

Key Size	American (mm)	Swiss (mm)
5/0	1.6	1.25
4/0	1.8	1.5
3/0	2.0	1.75
2/0	2.2	2.0
0	2.4	2.25
1	2.6	2.5
2	2.8	2.75
3	3.0	3.0
4	3.2	3.25
5	3.4	3.5
6	3.6	3.75
7	3.8	4.0
8	4.0	4.25
9	4.2	4.5
10	4.4	4.75
11	4.6	5.0
12	4.8	5.25
13	5.0	5.5
14	5.2	5.75
15	5.4	6.0
16	5.6	6.25
17	5.8	6.5
18	6.0	6.75
19	6.2	7.0
20	6.4	7.25
21	6.6	7.5
22	6.8	7.75
23	7.0	8.0

_{Winding crank in a miniature Vienna Regulator}

There is no key required for weight-driven clocks that have weight chains. Winding involves pulling the weight(s) to the top of the clock once each week.

Check out this article on How to Wind A Mechanical Clock

Choosing the correct clock key is essential for the proper functioning and longevity of your mechanical clock. Whether you’re winding an antique mantel clock, a grandfather clock, or a time-only carriage clock, using the right key size ensures smooth operation and prevents damage to the movement.

With a variety of key sizes available, understanding your clock’s requirements and keeping the key in a safe, accessible location will help you maintain your timepiece in excellent working condition. By following the guidelines and chart provided, you can confidently select the correct key and enjoy the reliable performance of your clock for many years to come.

August 31, 2017

Tag: 7

Top ten blog articles of all time – my blog, of course

The experts are going elsewhere and that is fine with me because this blog was never intended to appeal to those running a repair business or involved in the commerce of antique clocks