Seiko 6139-7100 ‘Helmet’ Chronograph

I have been getting a lot of requests lately for Seiko servicing and restoration. Traditionally, it wasn’t something that I did as I stuck to Swiss movements but the more I have been doing the Seiko 6139 the more enjoy them. I think they are going to be something that I start taking in a lot more of. I know that many people collect them but there aren’t many watchmakers who take them on.

Vintage Seiko’s can be had for not much money in today’s insane vintage market. They are an incredibly reliable movement and having been designed in 1969 they still stand up today. They share a lot of similar architecture with the Rolex 4130 movement which was developed several decades later.

Here is the Seiko 6139-7100 ‘Helmet’ chronograph. Such a great design in my opinion.

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Re-Bushing A Barrel – Omega Speedmaster 321

Re-bushing a barrel is such a crucial aspect of watch servicing, but it is seldom done. Anytime a watch doesn’t have a jeweled barrel or center wheel, there will be wear.

A barrel and center wheel have steel arbors or pivots. When they use a jeweled bearing the jewel is the harder of the two materials. When they just sit in the brass mainplate and bridge the steel is the harder of the materials.

Due to this fact, the plates wear before the pivots and arbors.

When this happens the plates must be drilled out and new brass bushings need to be installed.

The arrows below point to the plates that have worn holes. That is where we will drill and install the bushings.

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Reading & Understanding Watch Timing Machine Results

I see a lot of people on watch forums these days have purchased a watch timing machine to be able to see how their mechanical watches are running. I have noticed that most of them don’t know how to accurately read those results to get a clear idea of what is going on. I have made this video to hopefully clear up some of that confusion and help you to understand exactly what the numbers mean.


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Overhaul Procedure – Rolex Explorer II (3185)

This Rolex Explorer II wasn’t recently brought in. In addition to a standard overhaul, the customer wanted to update the look and change the dial and hands from black to white.

Here is the watch as it was brought in. Black dial with silver-colored hands.

I opened the watch to perform my initial checks and make sure no other parts were needed.

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Black Polishing Screws – Omega Speedmaster (321)

There is nothing more unsightly than watch movement screws that have been hacked to oblivion my sloppy workmanship. It is, sadly, something that is seen far too often in watch movements that I come across. We can take the below Omega Speedmaster as a perfect example. This reference happened to be 2998-1, a very rare and expensive Speedmaster reference. You can see below how bad the screws were. Fortunately, all was not lost and the original screws could be polished.

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Remove/Replace Worn Minute Wheel Post – Omega Speedmaster (321)

This Omega Speedmaster recently came across my workbench.


It was in quite a bad way and needed bushings installed for the upper and lower barrel and the upper and lower center wheel. It also had excessive wear on the minute wheel post and the intermediate minute wheel post. Unfortunately, jobs like this are usually neglected by watchmakers and cause poor performance of serviced watches.

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