Everything about spring bars – For all watches

Spring bars hold your watch in one piece, therefore you should make sure your spring bars are taken good care off.

What are spring bars?

Spring bars are metal bars or pins that have springs inside and are used to hold the strap of your watch to your watch case. Your watch case has two metal lugs and compressed in between them is the spring bar which fits into the holes of the metal lugs.

You can have spring bars in different lengths. This makes them fit different watch case sizes and different strap sizes. They also come in different diameters.

Why are spring bars important?

Whatever type of watch you have, whether it is cheap or very expensive, you need spring bars to keep your watch and strap together. They are very essential tiny pieces of metal without which your watch parts cannot hold together.

Because of their function, you should care and attend to your watch’s spring bar more often. They may be small, cheap, replaceable, and can easily be forgotten yet the role they play in keeping your watch intact is a very important one. If you break the spring bar of your watch, it could potentially break you watch when it falls from your wrist.

You can also use a spring bar to hold the buckle in place like it holds you watch case in place. Spring bars have to be removed if you need to change the strap of your watch or a buckle.

It may be a little tricky to remove a spring bar because it is spring-loaded, but with a special tool like a spring bar removal tool, the job can be made a lot easier.

It is, thus, important to use a high-quality spring bar for your watch. It has to be regularly checked and if necessary, changed. This can help keep your watch intact and save you from a possible expensive replacement.

The History of Spring Bars

No one really knows or is even interested in finding out who invented spring bars or where they came from. Recently though, one man named Jack Forster took it upon himself to answer the question of who invented the spring bar.

In his article “The Surprisingly Not Totally Boring Search For Who Invented The Spring Bar”, the author lays before us his relentless search for the answer.

He went back to the history of the wristwatch and with that, he made a trail of patents for a method of attaching a wrist strap with what looks like spring bars.

The oldest patent he found was from Charles Depollier in 1915. Charles Depollier was a pioneer in watchmaking in early American horology (the art of making clocks and watches).

This patent is for a system of converting a pocket watch into a strap watch. This system relies on a modern spring bar. He filed for the patent in 1915 and was granted in 1916. This was the earliest patent for a spring bar that Mr. Forster found.

The Elements of a Spring Bar

Watch spring bar length. There are many different kinds of watches that require different widths for straps or bracelets. This width should correspond to space in between your watch’s metal lugs. And this width also corresponds to the length of the spring bar. The length of your watch’s spring bar must be correct.

Watch spring bar pin or shoulder. This is the thinnest part of your spring bar. This part can be depressed and can fit into the hole in the metal lug. There are different dimensions for pin depth and diameter, and the diameter is very important.

If the diameter of your spring bar pin is too big, then it will not fit the hole in the metal lugs. But if its diameter is too small, then it will move inside the lug hole. With this constant movement, the lug hole can open wider and the bar can come loose. This can cause serious damage to your watch. Hence, the spring bar pin diameter of your watch must be correct.

Watch spring bar thickness. The thickness can be measured by taking the diameter of the thickest part of the spring bar. Thicker spring bars are more durable. It is also important that the thickness of the spring bar matches the opening or the divot at the end of the watch strap where you insert the spring bar to attach it to the watch case.

Flanges. You can find flanges is the most modern type of spring bars. These encircle the tip of the spring bar. Flanges make it easier to change a strap or a bracelet. Your spring bar tool will have something to grab onto when removing the spring bar.

Shoulder-less. Another type of spring bar is the shoulderless spring bar. This type of spring bar is used only when the watch’s lugs are drilled through. This means that the lug hole for the spring bar is drilled all the way through the lug. You will see the hole from the outside of the lugs.

How to Measure Spring Bars

There are two important sizes to measure in spring bars – the length or the width between the lugs, and the spring bar thickness or diameter.

Measuring an old spring bar using a digital gauge.

Digital gauge or digital caliper has jaws that can open and close to take measurements. It can give accurate measurements of tiny objects including spring bars.

Taking accurate measurements for spring bars is important so if you need a replacement, you can find the right one. This is the reason why you need a digital gauge since it can measure your spring bar dimensions accurately.

To measure the spring bar length, take your digital gauge and open the jaws to a length that can fit the spring bar between them. With your thumb and forefinger, hold the spring bar at the center and with your other hand, hold your gauge. Then position the spring bar between the jaws. The jaws must be open wide enough to allow the spring bar to fit in between them.

You can now slowly close the jaws while keeping the spring bar steady. Continue closing the jaws until the spring bar is held securely between them. Make sure to push the tips of the spring bar closed. Now you can take note of the reading of the measurement in millimeters.

It is good to write down the measurement of the spring bar length for easy reference. Double-check your result by repeating the measurement a second time. This will give you the closed length of your spring bar.

When you are measuring the length, make sure not to tighten the jaws too much. This could result in a bent spring bar.

After measuring the length, open the jaw a little to release the spring bar. Next, you want to measure the diameter or thickness of the spring bar. To do this, turn the bar sideways to make it perpendicular to your working surface.

Close the jaws around the diameter of the bar and measure the diameter in millimeters. Take note of the number for future reference. To be more accurate, repeat the measurement.

The measurements you have taken for the length and diameter of your spring bar can then be used for finding the correct replacement bar for your watch band.

Measuring spring bar length without a spring bar.

You will note that your digital gauge or caliper has two sets of jaws for taking measurements. One of these sets of jaws is used for taking measurements around an object and the other set of jaws is used for taking measurements inside of a space.

Without a spring bar, you can measure the width of the space between the metal lugs using the backward opening jaws of your digital gauge. Keep the jaws closed so that you can fit them easily between the lugs.

With one hand, hold your watch case steadily, and on your other hand, hold the digital gauge. Then slowly slide the backward opening jaws until its outer edges press against the inner edges of the metal lugs. The reading on the gauge gives you the measurement of the width between the lugs which correspond to the length of the spring bar.

Take note of this measurement for reference when you are selecting the right spring bar for your watch strap.

To measure the diameter of the spring bar, first fully close the backward opening jaw. Insert the tips of the jaws into the hole on the strap where you would insert the spring bar to attach it to the watch case.

With a very small hole diameter, the tip of the gauge will not have much extra space around it. If this is causing you much trouble, hold the gauge at an angle to fit them into the strap hole.

With the use of your index finger, slide the backward opening jaw slowly to open it. Continue opening the jaw until you can no longer move it. This gives you the measurement of the diameter of your spring bar.

Measuring spring bar length with a ruler or tape measure

The unit of measurement used to measure spring bars is the millimeter. Make sure that if you are using a ruler or a tape measure, they include lines that measure in millimeters.

Using a ruler or tape measure will only give you the measurement of a spring bar length but not its diameter. For this, you will need a digital gauge.

Simply place your spring bar against the ruler or tape measure. Then measure its length. Take note of the measurement for future reference.

If you don’t have any spring bar to measure with a ruler or tape measure, you can measure the width of the space between the two metal lugs of your watch case. This will also give you the measurement of the length of your spring bar.

Most spring bars have a diameter of 1.8mm. This size of spring bar fits most watches. There are also spring bars in 1.2mm and 1.5mm diameters. The lengths of spring bars range from 8mm all the way through 30 mm.

There are many different sizes and styles of spring bars sold. Most heavy watches need heavier spring bars. This means a larger diameter. Make sure to choose the largest diameter that would fit snugly through the hole at the end of the bracelet or strap. For length, find the longest bar that will fit between the lugs.

How to Remove and Replace Spring Bars

Things you can use to remove a spring bar include a common spring bar tool, a knife blade, or a sharp screwdriver. Slide the blade between the lug and the band. Then to free the bar from the lug, compress it with the blade. As you retract the spring bar, push it with your finger.

If you want to replace the bar, you first insert your spring bar into the clean lug hole. Then thread the spring bar through the strap or bracelet in place. The other retracted side should be held next to the knife or tool you are using.

Make sure that you put the other end of the spring bar as close to the hole as possible. With the spring bar tool, push the pin inwards towards the spring bar’s center and compress it. Make sure there is pressure while you push the pin into place. Then use your fingers to click the spring bar into place.

Make sure to double-check to find out if the strap is firmly held and that the spring bar pins are in both of the holes. This will ensure that your bars will not come loose.

IF you have shoulder-less spring bars, you can remove them by pushing a tool through the hole from the outside to compress them. This is an easy and popular method. And this is being used by watch owners who like to frequently change their watch straps or bracelets.

Cleaning Lug Holes

Lug holes also need to be cleaned often. When lugs holes are not cleaned they fill with grime and dirt because of everyday wear. When this happens, your watch bracelet will become loose. If you are attaching a new spring bar to your watch, it is important to clean these lug holes before doing so.

You can use a small screwdriver set and choose a tool that has a blade that is slightly smaller than the lug hole diameter. Insert the screwdriver blade in the hole and then rotate it so that the grime will be removed. If needed, press down to be sure the hole is deep enough to hold the new spring bar.

Curved Spring Bars

If your spring bars can help fit your new watch or bracelet, then you will be happy and thankful for it. However, there will be frustrating times when spring bars are unable to fit despite the many trials and errors you have done. You still cannot get the perfect fit for the watch band onto your watch.

Many times, you only need to make some minor adjustments to solve the problem. It can also take a slight bend or a curve on your spring bar to solve the fitting problem of your new bracelet or strap.

But this can still be a problem since not every watch can have a curved end fitted bracelets. Otherwise, there wouldn’t be a problem.

The fitting problem can be rectified with the use of curved spring bars. This is especially true for leather straps. With curved spring bars, you can adjust and bend the curve on the spring bar so that it could fit as closely as possible to the watch case.

Having curved spring bars is very convenient for people who have a lot of watches with the same lug width size. By using a different set of spring bars, you can now attach the strap on more than one of your watches.

Over time, watch cases have changed and developed. And this is also true of watch spare parts including spring bars. They have also been changed and adjusted so that they can accommodate newer watch models.

Today, curved spring bars are available in many different sizes including 18mm. 20mm, 22mm, and 24 mm. Still, the question arises. When should you use curved spring bars instead of the standard straight spring bars?

With curved spring bars, the profile of your watch case is followed. This gives you a bit more space between the watch case and bar. This will also allow you to use thicker and more durable straps on your watch.


Like the lug nuts on your car, you wouldn’t want the spring bar on your watch to be the wrong one with low quality. This is especially true since you take such good care of your watch model.

The material used for your spring bars should be of high quality. And make sure that they have the correct measurement. This is important so that your spring bars will not come loose.

Spring bars are indispensable and unavoidable in watches. This is the reason why they deserve love and respect. Their role is very vital even though it is very much taken for granted.

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