I recently overhauled this movement belonging to a New Haven wall clock.
Time mainspring: The original time mainspring was broken, and measured 3/4 inch wide by 0.018 inch thick. The replacement is 3/4 by 0.0165 by 96 inches, Merritt’s P-1956.
Strike mainspring: The movement came into the shop with a 3/4 by 0.0142 inch mainspring! It may have been original, but it had a jerky action after cleaning and lubrication. The replacement spring is 3/4 x 0.0155 inch thick (Merritt’s P-1496 in the orange and red box).
The video below shows the escapement action when the time mainspring is run down 7 1/2 days and then fully wound. The motion is sufficient but not excessive.
I recently overhauled this Ansonia walnut cased kitchen clock. The strong time mainspring of 0.018 inch thick, was causing wear to the mainwheel teeth, so I replaced the mainspring with a new one that is only 0.0155 inch thick (Merritt’s P-1496 in the orange and red box).
The first video below shows how good the escapement motion is with the thin time mainspring. It is run down 9 days in the video. The second video shows the entire movement in the case and then a closer view of the clock striking the hour and half-hour.
I just repaired this Seth Thomas mantel clock in a mahogany color Adamantine case. It has a No. 89 movement with a solid back plate. The case is 16 1/4 inches wide (including feet) and 11 inches tall. The bottom of the case has date code 81B (February 1918).
The escape wheel had two teeth that were too short due to damage by a previous repairer. The slide show below shows that the damaged teeth were removed, a brass plug inserted, and then 2 teeth filed to shape.
Both mainsprings were original Seth Thomas springs, one .0177 inch thick and the other .0165 inch thick. I don’t know for sure which one was originally on which side (time or strike). The .0177 inch thick spring was too strong. The thinner spring did not unwind smoothly. I replaced both with Merritt’s P-1956 springs 3/4 inch wide x 0.0165 inch thick x 96 inches long.
One thing strange about the case is that one end is mahogany Adamantine, but the other end is black! (see slide show below). It appears to have been made this way.
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).
I recently repaired this Seth Thomas tambour mantel clock. It needed to have the pivots polished and 14 bushings installed.
This clock was a good example of original thin Seth Thomas mainsprings. The time mainspring is 3/4 inches wide and 0.0159 inches thick. It is in good condition and was retained in the clock. The strike mainspring was 0.0164 inches thick. I intended to keep it in the clock, but it broke after cleaning, so I installed a 3/4 inch wide, 0.0165 inches thick, and 96 inches long, Merritt’s Antiques part no. P-1956.
Here is a slideshow of the clock and its movement, and also the label on the bottom of the case:
Here is a movie of the clock ticking and striking:
I recently overhauled this clock. The repairs included:
Polished all of the train wheel pivots (some were rough when the clock left the factory);
Installed 10 bushings (including rear time mainwheel bushing). One bushing had been installed by a previous repairer. It was crooked in the movement plate. To correct this, I installed a bushing with a hole too small for the pivot, then used a cutting broach to open the hole while uprighting it. Then the hole was polished with a smoothing broach;
Replaced the click on the strike mainwheel, as it was very worn, and had been filed down. I installed a steel clickspring, and a steel rivet;
Filed wear from the click on the time mainwheel, replaced the wimpy brass clickspring with a steel one, and replaced the brass rivet with a steel one;
Installed the correct size suspension rod, and installed an original Sessions mantel clock pendulum bob;
The strike mainspring was a replacement that was too thick (0.018 inches). I replaced it with a spring 3/4 inch wide, 0.0165 inches thick, and 96 inches long, Merritt’s Antiques part no. P-1956;
The time mainspring had been ground narrower by a previous repairer. It was rough with sharp edges. I installed the same type of mainspring as above, Merritt’s Antiques part no. P-1956;
The new mainsprings mentioned above (in the last two items) provide plenty of power to operate the clock. The movies below show the operation of the escapement, the clock striking, and the movement with pendulum. This clock strikes bim-bam on two chime rods.
Here is a slide show of some of the repair steps:
The label on the rear door says the following:
No. 277 P
Eight-day Turn Back
Striking the hours on Two-Tone Chime
Half-Hours in Harmony
The Sessions Clock Company
Forestville, Conn., U.S.A.
NOTICE
The Pendulum Ball and Key are fastened to bottom of clock.
DIRECTIONS FOR STRIKING
In order to make Clock strike the hour desired, turn the long hand up to twelve and allow the clock to strike. Then turn back to nine and forward again to twelve. Continue in this way until the Clock strikes correctly.
TO REGULATE
Should it be desired to have the clock run faster, place the small end of the key on the arbor at twleve and turn TOP of key to the left toward F. To run slower turn TOP of key to the right toward S.
There is a date code of 9-38 (September 1938) stamped on the label.
Most spring driven American antique clocks are overpowered (they have springs that are stronger than necessary). Even at age 100 years (give or take) the mainsprings are almost always strong enough to operate the clock reliably, assuming that the clock has been repaired properly, including POLISHING THE PIVOTS and installing bushings.
A spring should be replaced only if it is damaged (cracked or rusty). Some of the very old American springs (for instance from the 1850’s – 1860’s) are quite rough, yet they have operated the clock for all these years, and there is no reason to doubt that they will continue to operate the clock well. Yes, an old spring could break at any time, BUT SO COULD A NEW SPRING! I leave the original spring in the clock unless it is damaged. I install a weaker spring if the existing one is too strong.
French clocks are delicate, yet very efficient in operation, and I have not often experienced mainsprings that are too weak. The usual problem with French clock mainsprings is a torn hole in the outer end. A new hole should be made in the end, unless the spring is too short from having this operation done too many times.
About 1880, a fine Ansonia Regulator A, time only with calendar, was purchased for an office. The clock was enjoyed by many descendants of the original owner. It was well maintained, and always gave good service. In the late 1990’s, the clock was taken to a repair shop, and the repairman said he could not fix it! So he installed a chiming battery operated movement! The clock was passed down one generation, and the present owner was horrified at the indignity inflicted upon the clock. She asked me if I could find an original movement to install. I said I would try, but that it would take some looking, as the clock needs an earlier type of movement than is commonly seen.
After searching eBay for four weeks, I saw the exact movement we needed. It even had the original brass calendar hand and the hour hand. I bought it, and found a source for a good reproduction pendulum. A colleague supplied an original type minute hand to me. We had the case touched up, and an old glass painted with “Regulator A”.
I installed a Merritt’s Antiques P-1956 mainspring, as described in this post. This spring is 3/4 inch wide, 0.0165 inch thick, and 96 inches long. It is of excellent quality, and provides the correct amount of power.
