Witschi’s Inspector Gadget Assists Patek Philippe’s Watchmakers

Witschi clocks the watches that collectors count on.

Watches keep track of the time for the world, but who is making sure they do their job properly? Essential to both watch production and servicing, timing machines can measure a timepiece’s accuracy to within a fraction of a second. A tiny microphone captures the ticking of the watch and sends these signals to a monitor, which can display the interval between the beats. “It’s like an EKG of sorts, so you can see how well the escapement is working,” says David Bonilla, technical manager of the Henry Stern Watch Agency, which acts as Patek Philippe’s distributor and service center in the United States.
Swiss-based company Witschi (pronounced witch·e) has been making watch-timing machines and other testing equipment for more than 70 years, and Bonilla considers those products to be the gold standard of watch-testing equipment.Datenblatt_X1G3
During a recent tour of his service center in Manhattan, Bonilla explained that a timing machine tracks “the various ticks or the various small, little impacts of when the escape wheel hits the palette fork, when it hits the impulse plane and when it hits the locking plane” and measures the intervals between each event. “It will do the calculations, and it will say [if] this is falling within a certain tolerance,” he says. Patek Philippe’s Witschi machines are programmed to indicate performance parameters for its timepiece models. “The machine will automatically know which is the upper tolerance and which is the lower tolerance for a particular caliber.”
When a Patek Philippe watch arrives for servicing in New York, even before someone opens the case back, “we put it straight away on the time machine so we can tell how well the watch is running,” Bonilla says. Then based on the results, staffers determine the further investigations needed: The timing check is “always the basis or the beginning of starting to ask the questions.”

To assess the timing performance, a rotating arm on a Witschi machine puts a watch in six different positions: with the crown down, with it on the left, with it facing up, with it on the right, with the dial down and with the dial facing upward. But it takes a human to interpret a Witschi machine’s testing results.

Patek David Bonilla headshotBonilla equates a single timing-machine test to a person’s photo for an identification card: “That’s not [necessarily] indicative of how you usually look,” he says. Likewise a single timing machine test is just one snapshot at a moment in time. “If you have one bad result,” it’s not always a reflection on “the way the watch is running.” Sometimes because of gravity or a timepiece’s position, Bonilla says, “the watch gods don’t want it to work that well.” Nonetheless, “If you do another test, you may see that it’s fine. ”But after multiple tests, “if it’s wrong, then it is wrong and we have to do some corrective action.”

In addition, Bonilla’s team always tests a Patek Philippe watch being serviced on at least two different Witschi timing machines. “It’s a checks and balances thing,” Bonilla says. If only one is used, “what if there’s an error with the machine and it’s producing very good results for everybody?” he asks. “You need to confirm it with a separate machine.”
At Patek Philippe, the Witschi timing machines themselves undergo annual diagnostic tests to ensure their reliability. Witschi sells a GPS receiver to give timing machines a tune-up: This receiver collects time signals from the atomic clock that have been transmitted from GPS satellites. An average of those signals is used to calibrate the machine to assure stable and accurate timing.
Patek Philippe has several Witschi Chronoscope M1 machines, a timing machine still in wide use throughout the watch industry. Five years ago Witschi introduced a newer iteration, the Chronoscope X1, whose third generation, launched this year, includes even more functions, according to Witschi’s Urs Häni.
“Whenever a new piece of equipment comes into the workshop, and it’s something new that … makes it easier for us, we call it a toy,” Bonilla says.