Horological Meandering

I've Got Your Back, Part 4

This is Part 4 of our series on the casebacks used on our watches.

As I looked around on my bench, and reviewed photos of 100+ watches on my hard drive, I noted the retention systems used for the caseback. These are the most common:

Snap-on back which is pried off the case using a knife or tool
Screw-in back which is removed using a 2- or 3-prong case opener wrench
Screw-in back with special factory splined tool (Rolex key)
Back that sits on the case with gasket, fastened with slotted or Phillips screws
Back that sits on the case with gasket, fastened with special proprietary screws
Integrated case and back where the movement comes out the front
Mystery case where it's unclear how to open the case and the back is not removable
Reversos - where you can't tell where "the back" is
Ladies watches where the movement sits "in" the back

This installment will address these options.

1. SNAP-ON BACK

The snap-on back is common on inexpensive watches, especially quartz ones that have batteries needing replacement annually. I believe it's an irritating system. The caseback can be difficult to re-snap closed. It's hard on your thumbs pressing down if you don't have a press and fixtures to hold the watch. It's possible to break the crystal, bend the caseback, and/or to put the back on in the wrong orientation. Some companies make it easier by including a small tab so you can pry the back off, and align it correctly when reinstalling it. That tab is visible at the lower right on this Universal Geneve thin gold dress watch.

Some snap-on backs can be hard to remove. Most people use a case knife, razor blade or pry tool made for that purpose. If you can't remove the back with the watch in your hand, then use the fixture. The watch is clamped in between nylon-coated steel pins, then the pry tip is forced between case and back by turning in the screw on top. Then you can press the blue tab to twist the tip right or left to pop the back off (or gouge the case).

Replacing the back is often possible by pushing with your thumbs, but if that doesn't work, a press tool is required. This tool requires careful fitting of the nylon pushing die (to avoid landing on the lugs) and the support die (to avoid breaking the crystal). If the watch has a bracelet you have to remove one end in order to fit the tool onto the case.

A POP or CLICK is a reassuring sound. A CRACK means now you have to replace the crystal.

2. SCREW-IN BACK with generic tool

I think this may be the most commonly-seen method for retention, and the greatest cause of damaged casebacks. Two or more slots are engaged by a special tool, an adjustable pin wrench, a pair of needle-nose pliers, or a chisel. The caseback screws out of the case for removal. Buying a used watch with a chewed-up back would be disregarding evidence of a tampering owner.

[Raise your hand if you have ever buggered up a caseback.]

However, even the best tool might cause a mark, if the watch is gold or other soft material and the tool is hardened steel. In these instances the manufacture should have used a more appropriate method - but sometimes the same design is used for steel and precious metal and you (the opening person) just have to be very very careful.

This Seiko Sportura Kinetic Chronograph has never been opened. Round pins or oval-shaped teeth can be used to engage the back.

My IWC still has the plastic protector in place, after 13 years.

It is not uncommon to find a determined owner has used a punch and hammer to coax the caseback off a cheap watch! Don't try it.

Quality tools that should be used for removing a screw-on back. Various tips can be swapped to best fit the caseback openings. I have two wrenches so I can keep a different set of tips in each wrench.

3. SCREW-IN BACK with proprietary tool

As noted in the Rolex ads, the Oyster case takes a special key. Here is a set of 6 different sizes which I have used successfully to remove many a caseback. It also requires a fixture to hold the watch securely while you unscrew the back. There are many types of special tools - not all of them look like this.

Here's a very desirable Tudor watch, with caseback removed using the Rolex key.

Here's a Panerai that needs a special socket (or a huge open-end wrench).

4. BACK RETAINED WITH STANDARD SCREWS

Another common design is a caseback that matches up to the case and is held on by a number of small screws. These can be quite easy to get off, although it is possible to mess it up if the screws are rusted or soft metal.

Some screw retention systems are much better than others. This is Grand Seiko is well engineered, with many screws (each with its own O-ring).

It's hard to stop looking at the movement on this Minerva, and instead look at the caseback and screws.

This Vacheron Constantin gold watch was fitted with steel screws that had completely rusted from moisture on the owner's skin. It was quite a chore to remove and replace them. Servicing the movement was easy by comparison.

5. BACK RETAINED WITH NON-STANDARD SCREWS

You can't get into an RM or this Silberstein without their unique screwdrivers. This add a bit of expense for the manufacture to create and supply special tools, and guarantees the customers will come back for service. A number of brands have taken this combative approach to frustrate aftermarket watchmakers.

6. INTEGRATED CASE where movement comes out the front

A significant number of watches are designed with a case where the back does not come off. You pull the movement out of the front of the case. This can be done for a number of reasons - to make the watch thinner, to reduce costs, to improve the comfort of the back of the case, to reduce possibility of water intrusion, etc.

To make this work you need a crystal that can be pulled off from the front and a movement with a 2-piece stem so you can take the crown out. Waterproof watches need extra sealing on the front, and since they are often diver watches there are rotating bezel complications as well.

7. MYSTERY CASES

A few watches can cause their owners great anxiety, because they appear to be un-openable. Where is the seam? How does it come apart? I won't violate the watchmaker's code by telling you (it's on a need-to-know basis).

This large, manual-wind Swiss Army watch was designed with a quick-release feature for swapping straps. That also made the case construction a bit of a mystery.

When I tried to pop the back of this Grand Seiko, I was totally baffled by the case-within-a-case design. I haven't pulled the movement out any farther than this.

8. JLC REVERSO

By definition, the Reverso can be flipped over to reveal a "back" side that can either be blank or contain another dial. Thus does it have no caseback? Have you ever seen one dismantled? I never have seen a Reverso anywhere but on my arm or in a showcase. Here's how it looks on either side, and from the edge.

So I took one apart for us to inspect. There's no obvious part we can call "the caseback" - the functions served by a normal caseback are split and shared across other pieces of this watch case.

9. PRESS-TOGETHER FRONT-BACK

Small ladies watches in the past have commonly been held together by friction (no gaskets or screws). They don't have any waterproofing but do provide a limited amount of protection to the movement. I believe the assumption was these watches were worn in formal situations and so little protection was required. The movement sits in the "back" of the watch, and it is pressed into the "front" which holds the crystal and the bracelet.

Some men's watches used the same approach - I found an example in my photos of watches I've serviced:

You can separate the halves with a small screwdriver, or your thumbnail.

SUMMARY

As we have seen, there are a variety of ways to enclose and seal a watch movement. I wouldn't say there is one BEST way; it depends on the objectives of the company producing the watch. They can choose ruggedness, economy, simplicity, beauty, privacy ... or in the "case of Minase, a Japanese case maker I encountered a couple years ago, "The More Parts The Merrier" seemed to be the choice for case design.

Please come back for the next part of "I've Got Your Back".

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I've Got Your Back, Part 4

I've Got Your Back, Part 4

Really nice article and very educational!!

Fascinating......

Tools to open watches? Here's a candy store full of them

No wonder, one can scratch his watch....

Thank you for a interesting series of posts, Mike!