How to Measure a Spring Bar

Co-authored by wikiHow Staff

Last Updated: September 16, 2021 References

Spring bars, also known as spring pins or watch pins, are the tiny metal pins that connect your watch strap to your watch case and allows it to flex and move around your wrist. If you need to replace a damaged spring bar, or you purchased a watch strap that didn’t come with any to attach it to your watch case, you’ll need exact measurements to find the right size spring bar. Luckily, with a digital gauge, you can easily take measurements to find the perfect size, even if you don’t have an existing spring bar to measure. If you don’t have a digital gauge, you can find the length of the spring bar with a ruler or tape measure, but you won’t be able to accurately measure the diameter.

Method 1

Method 1 of 3:

Using a Digital Gauge

1
Open the jaws of the digital gauge slightly wider than the spring bar. A digital gauge, also known as digital calipers, uses jaws that open and close to take measurements and is able to measure tiny objects such as spring bars most accurately. Take your digital gauge and open up the jaws so they’re wider than the length of your spring bar so it fits between the jaws.
- When it comes to spring bars for watches, you need accurate tiny measurements to find the right replacement, which makes a digital gauge the best measuring device for you to use.
- You can find digital gauges at watch supply stores, jewelry shops, or by ordering them online.
2
Position the spring bar longways between the jaws of the gauge. With the jaws of the gauge open, pick up your spring bar and hold it in the center with your thumb and index finger. Hold your digital gauge in your other hand and move the spring bar so it’s positioned between the jaws.^{[1]
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- Keep the jaws wide enough to allow you to easily fit the spring bar between them.
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3
Close the jaws so they’re holding the spring bar to measure the length. Keep the spring bar steady between the jaws and slowly close them. Align the outer edges of the spring bar with the jaws of the gauge and close the jaws until they’re holding the bar securely between them. The digital gauge will give you a measurement in millimeters. Write down the length of the bar for easy reference.^{[2]
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- Close the jaws just enough to hold the bar. Be careful not to tighten them too much or you could bend your spring bar.
4
Rotate the bar so it’s perpendicular and close the jaws around it. Open the jaws a bit to release the spring bar and use your thumb and index finger to hold the bar as you remove it from between them. Turn the bar sideways so it’s perpendicular with your working surface and close the jaws of the gauge until they’re snug around the diameter of the bar to get your diameter measurement in millimeters. Write down the diameter measurement so you can reference it later.^{[3]
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Tip: Use your length and diameter measurements to find the perfect replacement spring bar.

Method 2

Method 2 of 3:

Taking Measurements without a Spring Bar

1
Position the backward opening jaws of a digital gauge between the lugs. A digital gauge, or digital calipers, has 2 sets of jaws to take measurements: 1 that closes around an object to measure it and 1 that opens inside of a space to take a measurement. The lugs are the 2 metal pieces that stick out of the watch case to hold the spring bar and strap. Insert the backward opening jaws between the lugs.^{[4]
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- Keep the jaws closed so they fit easily between the lugs.
- Pick up a digital gauge from a jeweler or a watch supply store. You could also order one online.
2
Open the jaws until they’re flush against the lugs to measure the length. Hold the watch case steady in 1 hand and your digital gauge in the other. Use your index finger to slowly slide the backward opening jaws of the gauge until both of the outer edges of the jaws are pressing against the inner edges of the jaws to find the length of your spring bar.^{[5]
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- Write down your length measurement so you have it as a reference when you select a spring bar to hold your strap.
3
Insert the tip of the closed jaws into the divot on the strap. Remove the jaws from between the lugs and close them so they’re fully shut. Insert the tip of the backward opening jaws into the small divot at the end of the watch strap where the spring bar is inserted to attach it to the watch case.^{[6]
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- The diameter of a spring bar is super small, so the tip of the gauge won’t have much extra space around it.
Tip: If you’re having trouble fitting the tip of the gauge into the divot, try holding the gauge at an angle to fit them into it.
4
Slide the jaws open inside of the divot to measure the diameter. Hold the strap and the gauge steady and use the index finger of your hand holding the gauge to slowly slide the jaws open. Continue opening them until they’re fully flush against the small divot of the strap to find the diameter of your spring pin.^{[7]
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- Write down your measurement and use it with your diameter measurement to find a spring pin that will attach your strap to your watch case securely.

Method 3

Method 3 of 3:

Finding the Length with a Ruler or Tape Measure

1
Use a ruler or tape measure that has millimeter measurements. Spring bars use millimeter measurements so in order to find the right fit, you’ll need to take your measurements in millimeters as well. Choose a ruler or a tape measure that includes the indicated lines that measure in millimeters.^{[8]
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- You can find rulers and tape measures at department stores, hardware stores, or by ordering them online.
Note: You’ll only be able to find the length of a spring bar using a ruler or tape measure. To find the diameter, you’ll need a digital gauge.
2
Find the length by measuring from the end of 1 shaft to the end of the bar. The spring bar consists of a slightly thicker shaft in the center with 2 thinner portions at each end that fit into the lugs. Hold your ruler or tape measure against the spring bar to measure the distance between the end of 1 shaft and the end of the bar to find your length.^{[9]
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- Write down your measurement so you can reference it later.
3
Measure the space between the lugs if you don’t have a spring bar. If you don’t have a spring bar to measure, hold your ruler or tape measure against the lugs on the watch case. Measure the space between the 2 lugs to find your length measurement.^{[10]
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- Because the 2 ends of the spring bar will fit into the lugs, measuring the space between them will give you an accurate spring bar measurement.