Wednesday, July 6, 2016

Tool of the Week: Measuring devices

***From Apprentice Corner

One absolutely critical part of watchmaking is measurement.  The importance of which has already been well drilled into me. As the old adage goes, “measure twice, cut once”, but I’ve found this advice is defied here. The process used here can be better summed up as “measure twice, with three different tools, cut once”.

Most watch manufacturers follow an assembly-line process. The parts are produced en-masse, large batches of single parts are allocated to one worker and they add their part into the watch as it is passed along the line. Little measurement is performed; if it fits and appears to work, job done. Pass it along. Of course, this is fraught with danger. It might work, but if the components aren’t precisely the right size, parts will rub, gears won’t mesh exactly, springs won’t expand and contract properly. It all comes full circle eventually.

Though it’s early days yet, I’ve already got a feel for how things are done here. Every step is preceded by careful measurement to make sure the parts meet exact parameters. It’s a painstaking process.

Perhaps too pedantic, honestly. But it doesn’t hurt.  When you’re working with components 1/10th the width of a human hair there is no margin for error. It fits exactly, or not at all.

We’ll be working on something soon that requires measurement to a thousandth of a millimetre. I’m not even sure what such a device would look like, but it probably won’t come cheap. Whilst a good pair of callipers (which measures a 10th of a mm) might cost $50, a micrometre tool (100th of a mm) costs $500. Extrapolating out, a tool to measure a thousandth of a mm might well cost $5000 and above.

Until next time,


Two modern measuring tools, and on the right, 1920s callipers handmade by a French apprentice watchmaker.

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