I provide this chart to assist those who repair old Westclox clocks. ClockHistory.com is not a parts supplier - please do not ask us for parts. The fine clock parts suppliers listed on my links page will be happy to send you a catalog if you would like to order mainsprings.
If you know of anyone that sells old Westclox parts, and I will put the information on this web page.
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America (ca. 1927)
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Time spring | Same as Big Ben Loud alarm | ||||||||
| America (ca. 1927) | Alarm spring | Same as Ironclad | ||||||||
| Bunkie and Sleep-Meter Intermittent | Time spring | Same as Big Ben Loud Alarm | ||||||||
| Bunkie and Sleep-Meter Intermittent | Alarm spring | 5/16" x .013" x 48" | ||||||||
| Baby Ben (mov't. 1, 1912 to mid-1914) | Time spring |
6.2 mm (just under 1/4") x .0102" x 29" hole end
New replacement: 1/4" x .010" x 26" loop end, convert
to hole end. (Note: 29" long would be better, but I haven't found one available. The 30 inch long spring will run the clock for about 30 hours.) |
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| Baby Ben (mov't 2 - 4, mid-1914 to 1960) (up through Style 7 two key wind) | Time spring |
5/16" x .0087" x 30" hole end (measured in type 2
& 3 movements)
5/16" x .009" x 30" hole end (SPR-3414 factory material) New replacement: 5/16" x .009" x 36" loop end, cut off 6" and make hole in end. (CMH-80.2 or 80.3) |
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| Baby Ben (all two key wind) (Style 1 through Style 7 two key wind) | Alarm spring |
7/32" x .0082" x 27" hole end (measured in type 2
movement)
7/32" x .0087" x 27" hole end (SPR-3246 factory material) New replacement: 7/32" x .008" x 26" hole end (CMH-56.1) |
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| Baby Ben single key wind (mov't. 5) | 9/32" x .0085" x 41" hole end | |||||||||
| Big Ben Loud Alarm (mov't. 1 - 2, 1908 to 1956) (Style 1 through Style 6) | Time spring | 5/16" x .015" x 40" hole end (Timesavers 17489, CMH-80.13) | ||||||||
| Big Ben Loud Alarm (mov't. 1 - 2, 1908 to 1956) | Alarm spring |
1/2" x .0138" x 40" loop end (Style 1 Style 2)
1/2" x .0138" x 32 1/2" loop end (Style 4, 5 and 6) |
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| Big Ben Chime Alarm (mov't 3, 1931 - 1956) (Style 3 through Style 6) | Time spring |
Same as Baby Ben mov't 2 - 4
5/16" x .0088" x 30" (SPR-3418 factory material) |
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| Big Ben Chime Alarm (mov't 3, 1931 - 1956) (Style 3 through Style 6) | Alarm spring | 9/32" x .0105" x 20" loop end (measurement of factory original spring) (CML-70.6 is close) | ||||||||
| Clock of Tomorrow | 5/16" x .010" x 72" (CMH-80.10) | |||||||||
| 8-Day Jeweled model 261 & 262 | Time and Alarm Springs | 1/2 x .016 x 66 loop end (CML-127.3). This is a Seth Thomas movement No.110. | ||||||||
| Ironclad | Time spring | Same as Big Ben Loud Alarm | ||||||||
| Ironclad | Alarm spring |
3/16" x .0155" x 25 3/4" hole end (measured in clock)
New replacement: 3/16" x .012" x 31" loop end (CML-48.4), cut off loop and make a hole |
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| Model 66 (Bingo, Raven, Waralarm, etc.) | Time spring | 5/16" x .0125" x 24" loop end | ||||||||
| Model 66 | Alarm spring |
Type one: 1/4" x .008" x 18 1/2" loop end
Type two: 1/4" x .0085" x 14" open loop end. SPR-3254, model 66AH. This type of spring may be installed without dismantling the movement. |
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| Sleep-Meter (also fits Black Bird, Blue Bird, Ironclad, Jack o'Lantern) ca. 1924 | Alarm Spring | 7/32" x .01" x 40" loop end (measured in Black Bird dated 1924 on movement.) | ||||||||
| Travalarm | 5/32" x .0093" x 35" (measured in 12-65 example). Can use CML40.3 (5/32" x .009" x 38 1/4") from S. LaRose and shorten it by 3". | |||||||||
| Two-inch movement (time only) |
7/32" x .012" x 29.5" loop end (measured in clock)
New replacement: 3/16" x .012" x 31" loop end (R & M and Timesavers) |
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Compute the correct length of the time spring for the Big Ben Loud Alarm:Length = Pi(B squared - A squared)/2t
Doing the computation, Length = 49.2". If a spring this long were used, the clock would run longer on a winding than with the standard 40" spring. |
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