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Over the past three years, I’ve posted about mainsprings for antique American clocks. I started with a post on June 12, 2007 about a mainspring from Merritt’s Antiques.

Most clock parts distributors offer a “standard” American loop end 8-day mainspring 3/4 inch wide by 0.018 inch thick and 96 inches long. These springs are too strong! They may cause severe wear to the clock’s mainwheel teeth. A thinner mainspring about 0.0165 inch thick should be used instead. (Regarding mainspring replacement, I believe that the original mainsprings should be kept in an American antique clock unless a spring is broken, damaged or too strong. Notice that I said “too strong” – the old mainsprings are almost never too weak!)

Several clock parts suppliers offer the thinner mainsprings for American clocks, typically 3/4 x 0.0165 x 96 inches. Clock repairers have noted inconsistencies in these springs – the thickness and strength can vary from batch to batch. I recently bought springs from 3 suppliers to test. For each spring, I measured its thickness, and its diameter when first removed from its retainer. On some springs I also measured the diameter after being fully wound and unwound 2 times.

The measurements are given below, with the mainsprings placed in categories based on my recommendations. At times, a supplier will ship mainsprings from a different source. The mainspring types pictured below show the appearance of the springs that I measured.

Recommended Standard Length Springs – 96 Inches Long

Timesavers 18790, Specified as 3/4 x 0.0165 x 96 Inches

Sample 1) 0.0165 inch thick, opens to 10″ (this spring has some rust on the outside and will be exchanged for another.)

Sample 2) 0.0162 inch thick, opens to 11.5″

R & M Imports 77.308, Specified as 3/4 x 0.0165 x 96 Inches

Sample 1) 0.0160″, opens to 11″, 9.5″

Sample 2) 0.0160″, opens to 11.5″

Sample 3) 0.0160″, opens to 11″

Sample 4) 0.0158″, opens to 13″

I have been using this spring from R & M for years. Typical batches from 4 – 5 years ago measured 0.0165 inch thick. There was a batch about 2 – 3 years ago that had brittle inner ends that broke easily. Current springs seem fine in this regard.

R & M Imports 83065, Specified as 3/4 x 0.0165 x 96 Inches

Sample 1) 0.0160″, opens to 11″, 9.5″

This sample is identical to the above spring (R & M 77.308) and costs over twice as much, so there is no reason to buy it!

Merritt’s Antiques P-1496, Specified as 3/4 x 0.0165 x 96 Inches

New springs purchased May 2010:

Sample 1) 0.0159″, opens to 12″, 11″

Sample 2) 0.0161″, opens to 12″, 10″

I first used this mainspring 4 – 5 or more years ago. Some batches have been significantly thinner than others. A batch that that I purchased in October 2008 is packaged the same as this current batch. The springs  have the following measurements:

Sample 1) 0.0165″, opens to 11″

Sample 2) 0.0165″, opens to 11″

Sample 3) 0.0158″, opens to 11″

Sample 4) 0.0165″, opens to 9″, 8″

Sample 5) 0.0165″, opens to 11″

Sample 6) 0.0156″, opens to 11″

An older batch with plastic inner wrap had thinner springs:

Sample 1) 0.0157″, opens to 11″

Sample 2) 0.0155″, opens to 11″

Another old batch (probably 4 – 5 years old) marked “Anchor” on the plastic inner wrap contained mainsprings that were very thin:

Sample 1) 0.0135″, opens to 10″

Sample 2) 0.0140″, opens to 12″

Around June 2007, Merritt’s was shipping a different mainspring under this part number. It was the same as the R & M 77.308 and the Timesavers 18790.

Recommended Long Springs

Timesavers 15959, Specified as 3/4 x 0.0165 x 120 Inches

Sample 1) 0.0160″, opens to 12″

Sample 2) 0.0168″, opens to 13″

120 inch long mainsprings are sometimes recommended for more uniform timekeeping over a one week running period. I have had excellent results with the 96 inch long springs, however, and recommend them for most movements.

Springs That Are Very Strong

Merritt’s Antiques MS309, Specified as 3/4 x 0.0165 x 96 Inches

Sample 1) 0.0158″, opens to 15″, 13″

This is the type of spring made in Germany that is very springy. The package has a yellow label saying “Beco Technic Germany”. They are tempered to a straw color instead of blue like many other springs. I don’t like to use these in average American antique clocks, as they provide more power than necessary.

Merritt’s Antiques MS310, Specified as 3/4 x 0.0165 x 108 Inches

Sample 1) 0.0152″, opens to 21″, 18″

This spring is by Beco Technic Germany just as the above spring. It is intended for the Seth Thomas No. 89 movement. It may be stronger than necessary, and I prefer to use springs in the first or second categories above instead.

Springs That Are Very Weak

Merritt’s Antiques P-1956, Specified as 3/4 x 0.0165 x 96 Inches

Sample 1) 0.0165″, opens to 6″

Sample 2) 0.0165″, opens to 6″

Springs in this batch open out to only 6 inches when released from their clamp. They are not very springy and are too weak for most American antique clocks.

The springs in my first batch two years ago were excellent! They opened out to 11 – 12 inches when released from their clamps, and provided plenty of power. I used these springs in several clocks. But batches received last fall and later have been very weak. So I don’t routinely use these springs anymore.

Other Springs

Timesavers 29515, Specified as 3/4 x 0.016 x 108 Inches

Sample 1) 0.0153″, opens to 28″, 20.5″

This spring seems way too powerful. Also, the surface is not smooth and the spring has a rough action.

Conclusions and Recommendations

For American antique clocks, I keep original mainsprings in the clock unless there is a good reason to change them. For replacements, I prefer springs from the first category (Recommended Standard Length Springs – 96 Inches Long). Many typical Seth Thomas, Ingraham, Gilbert, Sessions and New Haven clocks can use these springs.

Ingraham mantel clocks with deadbeat (or almost-deadbeat) escapement can use a somewhat thinner spring for the time side of the movement.

Some Waterbury and Ansonia movements made from the 1880′s through the 1920′s originally had mainsprings 0.0145″ to 0.016″ thick. It is important to select the proper thinner spring for these clocks.

It is best to measure and label new mainsprings when you receive them. After a time you can build up a stock of normal, thicker and thinner springs, so you can choose the proper mainspring when a mainspring does need replacing.

I believe that routine mainspring replacement should be avoided in antique American clocks.

Thanks to Len Lataille for encouragement to measure these mainsprings.

Related posts:

1. Replacing Mainsprings in American Antique Clocks
2. Mainsprings for American 8 Day Clocks
3. Bushing American Antique Clocks
4. Things a Clock Repair Shop Should Not Do to Antique Clocks
5. Things to check when repairing an antique American clock movement
6. 30 Hour Spring Driven American Shelf Clocks

I repaired this Gilbert “Parole” shelf or parlor clock that was made about 1880. The walnut case is 19 1/4 inches tall. I polished the pivots and installed bushings (a previous repairer had punched the pivot holes to try to close them).

The clock had its original mainsprings, both of which were marked “W. Barnes Patented Nov. 27, 1866″. The strike spring was quite thick (0.02 inch). Both springs were stiff and very hard to remove from the mainwheels. I installed new Merritt’s P-1956 mainsprings that are 3/4 by .0165 by 96 inches. They provide a good escapement action and striking speed. Gilbert clocks of this type take a large pendulum swing with a small amount of supplementary arc (overswing) due to the design of the recoil escapement. I slanted the back of the mainspring arbor hooks to make the mainsprings easier to remove for future cleaning.

The video below shows the escapement action with clock fully wound and then run down 8 1/2 days, then shows the movement and then the entire clock.

Repair job 4957.

Related posts:

1. Russell & Jones Hanging Oak Parlor Clock
2. Gilbert Tambour Mantel Clock, 1919
3. Original Mainsprings in a New Haven Long Drop Octagon Clock
4. Gilbert Tambour Mantel Clock with Bim-Bam Striking
5. Ithaca Grandfather Clock with Gilbert Movement
6. Mainsprings for Seth Thomas Queen Anne, Time and Strike, with Second Hand

I repaired this New Haven long drop octagon clock. Some of the pinions had worn wires, so I replaced the wires in one pinion and reversed the wires in three. I polished the pivots and installed 13 bushings.

The mainsprings appear to be original (they match in color and style and look old).

Time mainspring: 3/4 inch wide by 0.0172 inch thick. This spring provides sufficient power, as the escapement motion is excellent.

Strike mainspring: 3/4 inch wide by 0.0142 inches thick. This spring is very thin, yet the striking speed is fine.

I retained both original mainsprings in this clock. They were in good condition, operated smoothly, and provided enough operating power, so there was no reason to change them. A good old mainspring is no more likely to break than a new one. (Some repair shops install new mainsprings in every clock they repair, I disagree with this practice.)

The case is 33 inches tall, and the minute track diameter is 11 inches.

Repair job 4955.

Related posts:

1. Mainsprings in New Haven Long Drop Clock Movement
2. Welch, Spring & Co. “Verdi” Drop Octagon Wall Clock
3. A Tale of Three Movements and a Clock (Ansonia Long Drop Regulator A)
4. Ansonia Short Drop Schoolhouse Clock Movement
5. New Haven Oak Kitchen Clock
6. Replacing Mainsprings in American Antique Clocks

I recently overhauled this Sessions black mantel clock from around 1903 – 1910. It was a routine overhaul including polishing the pivots and installing bushings. A previous repairer had installed two screw-in bushings (a no-no!). I replaced these with KWM size 4 American bushings. The mainwheels were made with Gilbert-style clicks, which are more robust then the standard Sessions clicks.

The original mainsprings seemed too strong. The time spring was 0.0182 inch thick, and the strike spring was 0.0178 inch thick. I replaced both with thinner mainsprings, Merritt’s Antiques P-1956, 0.0165 inch thick, to reduce future wear to the mainwheel teeth. The escapement takes an excellent motion.

Repair job 4949.

Related posts:

1. Sessions Tambour Mantel Clock, Made in 1938.
2. Mainsprings for American 8 Day Clocks
3. Mainsprings for Seth Thomas Adamantine, 89C Movement
4. Mainsprings for Seth Thomas Oak Kitchen Clock
5. New Batch of Merritt’s Clock Mainsprings
6. Merritt’s Antiques P-1956 Mainsprings

This 8 day time and strike Ansonia movement was probably made in the 1880s. It has 5 pillars, and the plates are 5 3/4 inches tall. The movement goes to an oak schoolhouse (drop octagon) case 25 inches tall with an 11 inch dial.

A previous repairer had very badly bushed the front time second wheel pivot hole, and mutilated the pivot and shortened the arbor in the process. I added on to the arbor to restore it its original form, and installed a good bushing.

The time and strike mainsprings were old replacements that were too strong (0.0184 inch thick) made by Usibel, France. I replaced them with Merritt’s P-1956 3/4 by 0.0165 by 96 inch mainsprings.

Here is a video showing the escapement. The motion is excellent, even with the thinner mainspring. The mainspring is unwound about 8 turns (8 days of running) in the video.

Job 4962.

Related posts:

1. A Tale of Three Movements and a Clock (Ansonia Long Drop Regulator A)
2. Ansonia Walnut Kitchen Clock – Older, 5 Pillar Movement
3. Mainsprings in New Haven Long Drop Clock Movement
4. Ansonia Walnut and Oak Shelf (Kitchen) Clocks
5. Ansonia Iron Case Mantel Clock with Small Round Movement
6. Original Mainsprings in a New Haven Long Drop Octagon Clock

I just serviced an E. N. Welch “Arditi” perpetual calendar clock. I disassembled the movement and cleaned it, but the only repair was replacing the click rivets, as the original brass rivets were coming loose.

This clock has a 27 3/8 inch tall walnut case, and was made in the 1880′s. The movement has very old mainsprings which appear to be original. They are thin (0.0153 inches thick for the strike spring and 0.0156 inches thick for the time spring) and do not seem very “springy”. Yet, they provide plenty of power and have no visible damage, and so I kept them in the clock. If a mainspring has lasted for over 120 years, it is likely to keep on working.

The video below shows how well this clock runs, even with the weak mainsprings (and it is run down several days, not fully wound).

Here is a slide show:

Repair job 4880

Related posts:

1. Replacing Mainsprings in American Antique Clocks
2. Mainsprings for American 8 Day Clocks
3. Measurement of Mainsprings for 8-Day American Antique Clocks, June 2010
4. 30 Hour Spring Driven American Shelf Clocks
5. Things to check when repairing an antique American clock movement
6. Bushing American Antique Clocks

I just repaired the movement of this Birge, Peck & Co. standard 8 day cornice and column shelf clock. The addrss of the printer of the label (Press of Elihu Geer, 10 State Street, Hartford) dates the clock to 1850 – 1855 (see ClockHistory.com) for reference).

The case is 32 3/8 inches tall, 16 9/16 inches wide and 4 7/8 inches deep at the bottom. The dial has a 7 inch time track. The dial and lower glass are original. The movement is a later version of that invented by Joseph Ives, having roller pinions instead of fixed trundles, and the plates are riveted strap brass instead of one piece stampings. It is weight driven with a recoil escapement.

Here are some movies of the clock and the escapement (showing the escapement before and after the adjustment for entrance drop):

Here is a slideshow of photos:

Repair job 4865.

Related posts:

1. Gilbert “Navy No. 26″ Oak Kitchen Shelf Clock
2. Seth Thomas 8 Day Four Sided Top Shelf Clock
3. Ingraham Oak Shelf Clock
4. Chauncey Jerome “Union” One-Day Shelf Clock, 1850s
5. Waterbury 8 Day Walnut Shelf Clock, 1880s
6. 30 Hour Spring Driven American Shelf Clocks

This 30 hour OG is the most recent addition to my collection (I don’t buy very many clocks these days, but I couldn’t resist this one). This clock was made about 1845, the fourth year that Seth Thomas made brass movement OG clocks. It has the early features described on my ClockHistory.com web site, and the unusual feature of a brass nameplate on the dial.

Here is a slideshow of photos:

• Ogee case, non-original lower glass, made in Plymouth Hollow, glasses held with wood strips. Height 26″, width 15 11/16″, depth 4 5/16″;
• Dial: metal, two rings drawn around time track, dots for minute marks;
• Early features of dial: tapered numerals 3, 4 and 8, small winding holes (8.2 mm);
• Unusual feature of dial: brass nameplate with S. THOMAS PLYMOUTH CONN U S A;
• Label: printed by Elihu Geer, Hartford, Connecticut, no address given. This dates it to 1842 – 1845;
• Movement: type 1.241, early.

Related posts:

1. A New Glass Tablet for My Early Seth Thomas Ogee Clock
2. Seth Thomas Oak Kitchen Clock with 89E Movement
3. Seth Thomas Cottage Clock with 8-Day Lyre Movement
4. Mainsprings for Seth Thomas Adamantine, 89C Movement
5. Two Seth Thomas “Plymouth” Tambour Mantel Clocks, 1938 and 1945
6. Seth Thomas 44 AG Clock Movement