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From The Bench: Springbar Specifications

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From The Bench: Springbar Specifications

You rarely think about them, but springbars are some of the most critical components of the watch.

They’re like lug nuts on your car—not glamorous, but if they fall off, so do the wheels, and then you have issues.
Oak & Oscar - Spring Bars and watchmaking
There are some important distinctions between springbar types, and there are right and wrong ones to install on your watch. 
Oak & Oscar - Spring Bars and watchmaking
The proper springbars ensure that your watch will stay on your wrist comfortably and reliably. The wrong springbars could fall out, dropping your watch into the raging sea, seize in your watch and force you to saw them out, or even damage the lug holes in your case.

For this reason, we encourage all Owners to seek out high quality retailers when purchasing more springbars.

There are a few different places to get high quality springbars for your watch: 

  • Watch Strap Retailers: Most of the watch strap makers out there will sell you bulk springbars with their straps. It's fairly safe to say their quality will be what you need to keep your watch securely on your wrist. 
  • Esslinger: Esslinger is a one-stop-shop for watch tools, parts, and supplies for watchmakers around the world. This variety kit will ensure you have the correct sprinbar for every watch in your collection. 
  • Jules Borel: Another watch parts supplier, Jules Borel provides unique, individual springbars no matter the watch you're wearing. This is where watchmakers go — it can be where you go too. 
  • Amazon: We try and resist the temptation to recommend Amazon, but their prices are hard to compete with and we've found no reason to believe their springbars are dramatically lower quality. 
Oak & Oscar - Spring Bars and watchmaking
Springbars are designated by length, diameter and tip type. Length is pretty easy—you simply get the same size as your strap.

Most Oak & Oscar watches take a 20 mm strap, so 20 mm springbars are the correct size.

The Burnham takes 22 mm straps, so 22 mm springbars are proper on that watch.

Note that the bars themselves will be slightly longer than their listed length, as they are meant to be under tension while in the watch, so they should stick out slightly when installed loose in the strap.
Oak & Oscar - Spring Bars and watchmaking

Springbar diameter is slightly more complex.

The listed diameter of a springbar is typically 1.30 mm, 1.50 mm or 1.80 mm, which denotes the diameter of the thick middle portion of the bar. Not typically listed is the diameter of the springbar tip, which is also important, but luckily the tip thickness is fairly standardized.

Fortunately, all Oak & Oscar watches take a 1.80 mm spring bar, so that part is easy.
Oak & Oscar - Spring Bars and watchmaking

What if my Springbar is too Thick or too Thin?

Too-thin springbars allow too much play for the strap, which can actually cause the bar to get pulled out of the lug.

Thin tips will also rub excessively on the inside of the lug holes, causing them to ovalise and expand, a problem that cascades progressively until the case needs to be replaced.

Springbars that are too thick typically just don’t fit. Most dangerous is when the tip is just barely too thick and makes a tight friction fit to the case, because those can become hard to remove.

Springbar tips should fit easily into the lug holes with a small, but perceptible amount of play. Again, standard 1.80 mm springbars are perfect in Oak & Oscar watches, but special springbars from other companies might cause an issue.

If it feels excessively tight, don’t force it!
A more narrow and wider springbar sitting side by side with a green background at Oak & Oscar
A certain type of springbar to avoid with Oak & Oscar watches is a non-standard size called Seiko “fat” or “fattie” springbars. These springbars have a thicker main body, which can fit some straps more securely, but they also have thicker tips, and that’s a problem.
Precise measurement device showing the width of a springbar
These tips measure about 1.1 mm thick, 0.2 thicker than our standard 0.90 mm springbar tips. While two tenths of a millimeter might not sound like much, it makes the tips just too thick to fit into the lug holes on Oak & Oscar watches.
Close up detail image showing a springbar set in an Oak & Oscar watch
If you really force it, the springbar will kind of wedge itself between the holes, but without making strong contact on either end. This is dangerous! The tiniest bump and the watch can fly off your wrist.
Close up detail show of a springbar that's too large for the lug on an Oak & Oscar watch
Worse still is if the springbar tips are slightly smaller than 1.1 mm, in which case they can friction-fit themselves into the lug holes. Bad news, and potentially terrible news on a case without through-holes like the Jackson chronograph, since you can’t push them out from the other side. 
Oak & Oscar - Spring Bars and watchmaking

Springbar Tip Types

The last consideration is tip type, and this is very important. Tips are typically described as “double flange” or “double shoulder.”

Oak & Oscar - Spring Bars and watchmaking
Double-flange springbars have two small flanges on the pins, allowing them to be manipulated by the fork of a springbar tool from the back of the watch. These springbars can be used on any watch, drilled lugs or solid.

When in doubt, choose double-flange!
Oak & Oscar - Spring Bars and watchmaking
Double-shoulder springbars are deceptively-named, and simply have two smooth pins extending from the central portion. These are designed only for watches with drilled lugs, and can be pushed in from the outside with the pin-end a springbar tool.

Only Olmsted and Humboldt have drilled lugs in our catalog, so these are the only watches that should be used with double-shoulder bars.

Oak & Oscar - Spring Bars and watchmaking

There is a final category of springbar that you might encounter on an Oak & Oscar watch, and that’s the specialized bar in the clasp of our bracelet.

Typical springbar tips are somewhat long, so as to provide a maximally-secure hold on the lugs. Clasp springbars, however, must fit into the thinner profile of the clasp itself, so they have proportionally-shorter tips to avoid sticking out the side of the clasp like a tiny pair of horns.
Oak & Oscar - Spring Bars and watchmaking
These springbars are only found in the clasp, so unless you accidentally shoot one off into the ether during an adjustment, you’re unlikely to encounter them.

The history and design of springbars may be interesting to the watch geek, so if you want to learn more, go read Hodinkee’s deep-dive from 2016 (this is one of Chase’s favorite articles)!
And for a TL;DR of this entire piece, here you go. Most Oak & Oscar watches take a 1.80 x 20 mm double-flange springbar, unless you have a Burnham, in which case it’s a 1.80 x 22 mm double-flange springbar.

Now go forth and change some straps!