Introduction
Mainsprings store and release the power that drives mechanical clocks. Choosing the wrong strength, length, or barrel-compatible size leads to weak running, overwinding issues, or damage to the movement. This guide explains how to choose the correct mainspring for your clock.
Understanding What a Mainspring Does
Stores mechanical energy
The mainspring powers the time, strike, or chime train.
Controls run duration
Correct length and strength ensure the clock runs for its intended duration.
Regulates power delivery
Incorrect mainspring strength causes erratic timekeeping or excessive wear.
How to Identify the Correct Mainspring
Measure the mainspring thickness
Thickness determines power output. Too thick causes damage; too thin causes weak running.
Measure the mainspring width
Width must match the barrel’s internal height to avoid binding.
Measure the mainspring length
Length determines run time and must match the movement’s design.
Matching Mainsprings to the Barrel
Identify the barrel diameter
The mainspring must fit the barrel without excessive tension or slack.
Match the arbor hook style
Different movements use hole-end, loop-end, or T-end mainsprings.
Check the barrel wall thickness
Thicker walls require specific spring lengths to avoid coil stacking.
Common Mainspring Materials
Blue steel mainsprings
Traditional and widely used. Strong and durable.
White alloy mainsprings
Modern alloy with improved strength and reduced breakage risk.
Tempered steel mainsprings
Used in high-performance or heavy-duty movements.
Common Mistakes When Choosing Mainsprings
Choosing a spring that is too strong
Excessive strength damages gears, arbors, and escapements.
Using the wrong width
Incorrect width causes binding or inefficient power delivery.
Guessing the length
Incorrect length affects run duration and power consistency.
Recommended Internal Links
FAQs
How do I know what mainspring my clock needs?
Measure the thickness, width, and length of the original spring or match the movement specifications.
Can I use a stronger mainspring for better performance?
No. Stronger springs cause excessive wear and potential damage.
Do all mainsprings fit all barrels?
No. Springs must match the barrel’s diameter, height, and arbor hook style.
Why does my clock run weak after replacing the mainspring?
The spring may be too thin, too short, or incompatible with the barrel.
Can I shorten a mainspring?
Only if the design allows it. Most mainsprings must match exact specifications.
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