This is the first Nomos Delta movement we’ve had in the workshop, and I’ve always wanted to get my hands on one.

This one has a power reserve (Gangreserve) indication in the little circle at 1 o’clock. The black visible in the slot indicates the state of the power reserve, so it’s powered down at the moment.

The case has a see-through case back, which is a nice idea, as the movement is a thing of beauty. The delta is derived from the alpha, but with the addition of the date indicator and a power reserve indication.

The amplitude is almost a bit too high, and the watch is running fast.

First look at the delta movement – from this side, it looks just like the alpha.

This is where the differences are. The date ring sits on the outside of the movement, which is pretty smart. This allows the date to sit at the very edge of the dial, which looks a lot nicer than a date that’s set further in. Have a look at the Junghans Max Bill for comparison. They use a bog standard ETA 2824-2, so the date ring sits way too far in, which looks odd. Good that Nomos makes their own movements, so that they can make decisions that impact positively on the design – other manufacturers that use bog standard movements can’t do that.

A detail of the date ring sitting on the outer edge of the movement.

In order to allow for the power reserve indication, the barrel is only suspended from the top, where the barrel arbor is screwed onto the ratchet wheel with three screws, which is also different from the alpha, a construction that we have seen before in Vacheron Constantin movements. The hacking lever is visible next to the sliding pinion.

This is the core of the power reserve indication.The lower disc with the black and white marking has 20 teeth, and drives a little planet wheel on the outside of the barrel. The lower wheel itself is driven by the barrel arbor. On top of that sits the wheel with the slot to show the power reserve, which has 19 teeth, so it turns slightly faster than the lower wheel, and thus moving the black into the window opening when the watch is wound.

Nomos supplies parts to independent watchmakers like us, and that’s why we love them (and because they make beautiful watches and movements). This allows us to order everything we need – a new barrel (as it’s riveted, so you can’t just replace the mainspring), a complete gasket set, and a new crown to assure that the watch is waterproof after the repair.

The gear train and the hacking lever go in.

The bottom plate with the new barrel.

The pallet fork is in and oiled with Moebius 9415.

The movement is ticking, and can now be adjusted.

The 301 degrees is a better amplitude, as we were a bit close to banking before. Beat rate and beat error are adjusted, and positional variation is great.

The date ring is on, and I can put the dial on.

The movement is cased again.

Ready for testing.