Seiko '64MAS' GMT Mod

The Story:

A couple months back, while on Reddit, I came across a post asking: "If you could only have one Seiko - what would it be?"

"What a stupid question," I muttered. I knew that Seiko, and in fact most commercial watch brands, would never in a million years make a single watch to satisfy everyone - how else would they be able to sell their other models?

However, it did get me thinking: How would I make my perfect Seiko?

The Build:

I settled on the following characteristics:

• Classic/Vintage aesthetic harkening back to Seiko's old designs

• Dive Watch with Screwdown Crown

• Bidirectional Count-Down bezel

• Date function

• GMT function

First, the look. It would not be unfair to say that I coveted a 62MAS. And when one looks at it, it's not difficult to see why:

I settled on the SPB143 dial, and got to the process of manually drilling and widening the centre hole so that it could accommodate my 'secret weapon' - the NH34/4R34 GMT movement:

Next, the hands. I always found the SPB143 hands too 'fat' and I wanted something which was nearly the same thickness for both the hour and minute hands. Rob at MonsterWatches provided an answer, and it was his description that sold me:

Now, the case. I settled on the CrystalTimes 707A SKX case. It was a 3 o'clock case with no crown guards, which would provide a good facsimile for the 62MAS shape. Combined with a 24H chapter ring and a double-domed sapphire crystal, it could accommodate the GMT function:

The crownguard-less design also meant that it could accommodate CrystalTimes' 243 big crown, giving it an even more classic aesthetic. I combined it with: what else, the CrystalTimes MM300-style bezel and Yobokies Count-Down bezel insert - the same combination I chose for my 6105/6309 mod.

With all parts in place, my 'perfect' Seiko diver finally took shape - Christened the "64MAS" after the NH34/4R34 movement it housed:

or those of you still pining for a 'perfect' Seiko, I encourage you to start building your own.

Parts List:

• Case: CrystalTimes CT707A w/ CT231 Caseback for NH series

• Crystal: CT037F Double-Domed Sapphire with Blue AR

• Bezel: CrystalTimes CT237 w/ Yobokies S104 Countdown Bezel and bidirectional click spring

• Dial: SPB143 with widened centre hole

• Chapter Ring: CT294 GMT with 24H Markers

• Hands: MonsterWatches (@monsterwatchesnl) 6105/62MAS Classic Style Hands with RC Tritec Grade X1 C3 / OEM SSK001 GMT Hand

• Movement: Seiko NH34 Automatic w/ Lumed Kanji Date

• Straps: CT903 22mm SS Oyster Bracelet / Strapcode 22mm Heat-Sealed NATO Strap in Admiralty Grey / Zuludiver x Bonetto Cinturini 286 NDL Rubber Strap

Specifications:

• Case Diameter: 42.5mm without Crown

• Case Thickness: 15.37mm

• Lug Width: 22mm

• Lug-to-Lug: 46mm

• Water Resistance: Rated by CT up to 200m; Self-Tested up to 6ATM