Monday, June 17, 2019

1900’s quarter repeater restoration - and what's the big deal about it?

Traditionally in horology, gear and pinion manufacturing are the most difficult tasks.
For even accomplished watchmakers, the ability to cut a gear in-house has been always been undisputed proof of a Master’s craftsmanship. However, the technical challenge with gear cutting has remained the same for the past 500 years: gear cutting and hobbing machinery and tools are not only very expensive but also very limited: one tool can cut just a few different 'profiles'. This meant a watchmaker was only capable of making a very limited number of gear train combinations and rarely any complicated clocks or watches beyond his 'standard' set.

This challenge presented itself in yet another form: the gear repair and restoration limits.  Chances that a Swiss watchmaker in the 1970’s would be able to make a replacement gear for an English pocket watch from 1870 were slim. The problem was not in skills, but lack of variety of gear cutters and hobbers at his disposal.

Over the past 100 years, only a handful of Australian watchmakers were brave enough to tackle the gear making problems and undertake such repairs in-house. Almost in all cases, the new gears were repaired by hand, employing basic techniques rather than made from scratch. And in the cases where gears were damaged beyond repair or missing completely, the end result was always just a fairly crude compromise.  In rare cases, when money was not an issue, fabrication was outsourced by sending the drawing to better setup shops and gear specialists in England.

The repair to a pocket watch which required a new gear - as shown below - is our solution to this centuries’ old watchmaking challenge.

1. We started with taking measurements of a broken gear

2. The next step was calculation and drawing in Solidworks

3. The Solidworks model was then translated into a Mastercam file which would execute cutting operations of the CNC EDM wire cutting machine. This includes not just the cut itself but all probing and measuring

4. Cutting of the new gear

5. Lapping of the new gear to match the thickness of the old one - by hand

6.  Comparing the profile

7. Riveting the new gear to the old pinion, by hand.

8. Installation and final check.

Clearly, the advantages of EDM wire cutting of watch gears are numerous:

- very little limitation to gear module, size and even shape. We are currently setup to make flat gears in diameter ranging from 5mm to 300mm
- ideal solution for high precision and high quality gears in prototyping and small batch series;
- no limits in regard to gear material! EDM technology enables cutting of almost any metal - from soft brass, aluminium to stainless steel, titanium, to tungsten.  The harder, the better!

Of course, the initial EDM setup does require significant investment in software, machinery, training and maintenance but we are already convinced that such investment is worth it.

While EDM is not a new technology in Australia, this is the first time in the history of local watchmaking that a service like this is available to fellow Australian watchmakers - even for one-off jobs. We remain at your disposal!

Again,  it is absolutely obvious that without the constant support of our brand ambassadors a project like this would only remain a dream. When you invest in our watch, you are becoming directly involved in a much bigger project that benefits not just a handful of young watchmakers but takes us all, together, as a country, to the next technological level.

Finally, here is a short video of the quarter repeater striking again:

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