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What the 2015 visit covered
Broer’s Seiko Media Experience included seminars on Astron, Grand Seiko, and Prospex; factory visits focused mainly on Grand Seiko; an interview with Seiko’s CEO; and a museum visit. He divided the larger trip into three reports. Part 1 concentrates on Morioka and Shiojiri.
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He emphasized that Seiko’s organization was more complex than a simple two-factory map. In his 2015 account, Seiko Instruments Inc. (SII) was the Morioka facility, Seiko Epson was the Shiojiri facility, and Seiko Watch Corporation handled worldwide sales and marketing and invited the journalists. These are the organizational descriptions in the report, not confirmation of present-day corporate roles.
Broer summarized the distinction this way: “The two factories, in Morioka and Shiojiri, are used to develop and manufacture (Grand) Seiko and Credor watches, but have different fields of focus.”
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Morioka: mechanical Grand Seiko and Credor
At the SII facility in Morioka, Broer saw work associated primarily with mechanical Grand Seiko and Credor: movement-parts manufacture, assembly, casing, fine-tuning, and testing. He also reported that some Prospex watches using caliber 8L35 were assembled and cased there. The article describes watchmakers at individually fitted wooden workstations and Seiko’s in-house training and certification, including Meister and Specialist tracks.
The 9S mechanical family
The report identifies 9S as the mechanical Grand Seiko family and names several calibers. It calls the 9S65 a base automatic caliber with a stated 72-hour power reserve and the 9S85 a hi-beat caliber with a stated 55-hour reserve. It also mentions GMT variants 9S66 and 9S86, and the hand-wound 9S64. These specifications are the figures given in Broer’s 2015 account.
Broer describes the 8L35, used in Prospex Marinemaster models, as based on the 9S55. He also notes a small group of watchmakers working on Credor caliber 68, an extra-thin movement.
Assembly and inspection as observed
The sequence Broer describes proceeds from movement assembly to casing, water-resistance testing, bracelet fitting, visual inspection, and additional testing. He says Grand Seiko watches received an individual certificate for the tested watch and movement. This is what the journalist reported seeing; it should not be read as a verified description of today’s manufacturing sequence or test criteria.
The report’s historical test-criteria comparison
Fratello’s 2015 report reproduces a table comparing “Seiko testing program & criteria” with “Chronometer” criteria. The values below are historical figures from that table, attributed to Fratello Watches, not current verified specifications.
| Criterion in the 2015 table | Chronometer | Grand Seiko |
|---|---|---|
| Mean daily rate | -4 to +6 seconds/day | -3 to +5 seconds/day |
| Mean rate variation | 2.0 seconds/day | 1.8 seconds/day |
| Maximum rate variation | 5 seconds/day | 4 seconds/day |
| Greatest rate difference | 10 seconds/day | 8 seconds/day |
| Rate variation according to temperature | -0.6 to +0.6 seconds/day | -0.5 to +0.5 seconds/day |
| Positions | Five | Six |
| Test period | 15 days | 17 days |
| Test temperatures | 8°C, 23°C, and 38°C | 8°C, 23°C, and 38°C |
| Secondary error | Not stated in the table | -0.5 to +0.5 seconds/day |
| Rate resumption | -5 to +5 seconds/day | -5 to +5 seconds/day |
The table’s “Grand Seiko” column concerns the mechanical testing criteria shown in that report; it is not a comparison of the accuracy of 9S, 9F, and 9R movements as families.
Shiojiri: quartz, Spring Drive, and specialist studios
At Seiko Epson in Shiojiri, the 2015 tour centered on Grand Seiko quartz and Spring Drive production, as well as Astron GPS watches. Broer names the Takumi Studio, case studio, Micro Artist Studio, and dial workshop. In his account, Takumi assembled Grand Seiko and Credor quartz and Spring Drive watches. The Micro Artist Studio worked on high-grade Credor movements such as the Sonnerie and Minute Repeater, as well as the Eichi II.
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The report also records work on cases and dials: finishing cases, making and polishing markers, and bluing hands. These are observations from the 2015 visit, not evidence that the same work is assigned to the same locations today.
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The three movement families point to different ways of keeping time. The 9S is mechanical; 9F is quartz; 9R is Spring Drive. Broer’s factory account associates Morioka chiefly with mechanical Grand Seiko and Credor work, and Shiojiri with Grand Seiko quartz and Spring Drive, while warning that Seiko’s organization was more complicated than that shorthand suggests.
Broer judged the 9F movements to differ substantially from cheaper Seiko quartz movements, but presented that as an impression rather than a measured comparison. The report does not supply comparative performance tests across 9S, 9F, and 9R, so their relative accuracy or performance cannot be inferred from the factory descriptions.
Spring Drive’s mainspring-powered regulation
During the visit, Spring Drive was explained as a system that uses power from the mainspring to generate electricity for its Tri-Syncro regulator. That electricity is consumed rather than stored in a battery. An IC provides a reference signal to an electromagnetic brake, which regulates the wheel train; Broer connects this regulation to the seconds hand’s continuous glide.
As Broer put it: “The Spring Drive mechanism uses an electric speed control mechanism instead of a mechanical escapement.” He also reflected: “It is truly a very interesting development, but it needs some time to understand it and see that it doesn’t harm the mechanical soul of a watch.” Those are the journalist’s words, not statements attributed to a named Seiko representative.
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The article is valuable as a detailed account of the facilities, watchmaking tasks, and movement explanations shown to a journalist in 2015. Broer also praised the finishing and the transparency of what he was shown; those are his personal judgments. Because the report is historical and describes a hosted visit, it does not establish current factory assignments, present-day production methods, current testing criteria, or current availability of particular watches.
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