I build watch faces for Garmin. Some of them show a mechanical movement: Skeleton, Regulator, Skeleton Bridge and Smoked Crystal. The question I get about them is whether the wheels are only a picture. The wheels are a picture. What sits behind them is a calibre I had to solve the way a real one is solved, and this is why I bother.
1. First, a folder of photographs
Every one of these faces starts as a folder of photographs of real openworked watches: a Royal Oak Openworked, a Moser Streamliner Tourbillon Skeleton, a Blancpain Villeret Squelette, and a dozen more. I spend the first days doing nothing except looking.
I also drop one cheap homage in with them, on purpose, and it turned out to be the most useful image in the folder. At a glance it has everything a skeleton should have: bridges, wheels, screws, an open middle. It is also obviously wrong, and working out why is the whole of this first phase. Its spokes are all the same width. Its openings are symmetrical. Its bridges carry no bearings, so the wheels hang in space with nothing to turn on. Every surface has the same flat brushed texture. It looks like a skeleton drawn by somebody who has only ever seen one.
The rest of the folder is the opposite. A skeleton is a load-bearing machine with the metal taken away down to the last safe gram, so what is left is whatever carries a force, and no spoke is wider than its job. They also all keep an unbroken ring at the outside. Chaos in the middle, order at the edge.
Which is what a watch person clocks in half a second, long before they could say what they clocked. Is the movement complete, and is every part held by something? That became rule one: everything on the dial is carried by something, and that something traces back, piece by piece, to the wall of the case.
2. Solving the calibre
Then I design the movement: which wheels exist, how many teeth each one has, how big it is, where it sits. Barrel, centre wheel, third, fourth, escape wheel, pallet fork, balance, plus whatever the layout needs to get drive back out to the hands. This phase decides what the finished dial looks like, and almost none of it is a drawing decision.
Tooth counts come first and the radii follow. Two wheels can only work together if their teeth are the same physical size, and if you go the other way round, picking radii that look nice and deriving counts from them, you get teeth of different sizes on the same dial. That is what happened on the first pass of Skeleton: every pinion count had been taken from its radius, the mismatches ran to sixty percent, and nothing on that dial could have driven anything else. Positions get solved too. An arbor a fixed distance from two others has one place it can be, where two circles cross.
On Skeleton Bridge the barrel had to sit further out than its teeth could reach, so a plain idler goes in between to pass the drive along. It changes no ratio. Sixteen teeth is the smallest wheel that spans the gap and still meshes at both ends.
Other positions choose themselves, and that is my favourite thing I learned doing any of this. The fourth wheel turns once a minute, so the fourth wheel is the one that can carry a seconds hand, so the small seconds subdial goes wherever its pivot comes up through the plate. That is the whole reason small seconds sit where they do on a real watch. Nobody chose the position. The train chose it.
Underneath all of it is a tension with no free answer. Big wheels spread across the dial are what make an openworked face worth looking at, meshing pulls every pair of them tight together instead, and something still has to reach the middle to drive the hands. Run the train off-centre, as the look wants, and you need a motion works chain to get back, which only fits if the barrel is small enough to leave the centre clear.
3. Does the train actually run
A drawn movement is a claim. Before anything gets a surface, I test it as a machine. Every mesh first, for teeth of the same size. Then the rates, from the barrel out to the balance.
Skeleton beats at 28,800 an hour, eight beats a second, and the escape wheel advances one tooth per full oscillation, so one tooth every second beat. That two matters. Sources will happily pair the classic 80/10, 75/10, 70/7 train with 28,800, and that is an 18,000 train. Take one beat instead of two and the watch runs at double speed.
Skeleton has a tourbillon, so the chain from the barrel to the cage has to come out at 480 to 1. Then the cage turns once a minute, which is why a tourbillon runs at sixty seconds in the first place: at that speed it doubles as the seconds indicator.
Then the physical checks. Two parts at the same height may not overlap, every arbor needs a bearing above it and below it, and the click and its spring have to be there, because a mainspring that can unwind backwards is not a watch.
These find things. On one pass the tourbillon cage had no pinion on it, so the wheel meant to drive it had nothing to push against, and the cage was the only object on the dial held at neither end. On another the ratchet wheel was animated at three times barrel speed, when the click holds the ratchet still the whole time the watch runs. Nobody would have named that in a review. Plenty would have felt it.
4. Could a watchmaker assemble it
Running and buildable are different questions, and the second is harder. In a drawing a wheel turns perfectly well with nothing underneath it. So the render goes through a pass where it is treated as an engineering drawing, part by part, and asked whether somebody could put it together at a bench.
The mainplate starts as a full disc reaching the caseband, and the openings are cut out of it. Build it the other way round, as a ring with a few arms, and it stops short of the case, and every bridge foot outside that ring is screwed to nothing. A bridge is a beam, so it wants an anchor at each end; a cock gets one, out near the edge. A jewel goes where an arbor turns and nowhere else, and a screw holding nothing gets deleted.
The review of Skeleton at this stage came back with nine fatal faults, and it was the most useful hour in the project. Nine arbors had a jewel above them and open air underneath, so a lower plate went in behind the train, on skeletonised arms, reaching every one. The click spring had been screwed to the barrel, which turns; it moved onto the fixed bridge above. And the barrel had drifted far enough over the middle that its tooth roots passed a tenth of a millimetre from the hands' arbor, so the cannon pinion could never have reached the hands at all. What comes out the far side is a dial where the eye can follow any part to a bridge, the bridge to its feet, and the feet to the plate.
5. Materials and finishing
Only now does anything get a surface. The useful way to think about a finish is what it does in light rather than what it is called, and there are four behaviours. Black polish is binary: jet black at almost every angle, then blinding at one. A brushed or striped surface carries a soft bright band across its grooves, and the band sweeps along the part as the angle changes. Perlage scintillates, hard little points winking on and off inside a softer patch. Sandblasted matte simply gets brighter as it turns towards the light. Only the last of those four falls out of a roughness setting; the other three have to be built.
Then each face picks from a catalogue. Rhodium plate for the mainplate, a gilt train, blued screws, and that blue is an oxide film rather than a pigment, which is why it is more saturated than paint and shifts as you tilt it. The bridges get anglage, the edge filed back to forty-five degrees and polished to a mirror, about a fifth of a millimetre wide on the real thing.
There is one more trap, and it cost me a round. Polish on a part a few across comes out as a dark wire with a bright rim, because on a narrow curve the dark half of a binary finish is most of what you see. The tourbillon cage taught me that. With polished arms it read as a peace symbol. Thin parts get satin instead.
6. Lighting the metal
One light, from above, the way a ceiling lights a watch on a wrist. Then the only question that matters: what on this dial is allowed to be bright?
The rule I keep coming back to is that the biggest object is never the brightest. Bridges are the largest mass of metal on a skeleton and the least interesting thing on it, and getting that backwards is most of what makes a rendered movement look cheap. I got it backwards on the first Regulator render. The two small gauge pointers were the brightest metal on the whole dial, and a made-up bounce of light off the wrist lit the movement from below, so the plate glowed at the bottom, where nothing interesting was.
The answer is not to floodlight the tourbillon. A focal point wins by being different rather than brighter. On the best photograph in my folder it measures 119.5 against a movement mean of 119.9, which is to say exactly as bright as everything around it. It pulls the eye with hue and local contrast: a gold rim against black cage arms, a coloured jewel at the centre, the highest local range on the dial. That survives being shrunk to a watch screen. A brightness difference does not.
Where the bright pixels belong is the filed edges, and those are lines rather than areas, each one changing along its length as the edge turns away from the light. Anglage drawn as an even outline all the way round is one of the fastest tells there is.
Behind everything is the space between the parts, never pure black and never flat. It takes a little colour from the room, and it is brighter at the top than at the bottom. All nine of my reference photographs agree. One of my faces painted its void brighter at the bottom for months, on an argument about the wrist sitting underneath the watch, and the photographs settled it: a worn watch has a ceiling above it as well.
Colour comes last, and it has one hard limit. A colourway ships as a tint over a single grey master, the way plating recolours metal without touching its texture, and a tint can only take light away. So a deep red over bright steel comes back pale and chalky. Salmon pink is what I write in my notes when I see it. The way out is to draw the coloured part as its own body underneath and put the metal's highlight on top.
7. The night frame
Then the dial gets built a second time, for always-on. This is the dim version you see with your wrist down, and it cannot be the day dial turned down, because a screen in that state may only give out roughly a tenth of its normal light. Dim everything evenly and you get a grey smudge.
So the night frame is drawn from the same parts, on black, with the mainplate left out entirely. In a dark room a plate that size reads as black anyway, so losing it costs nothing anyone could see and hands the light budget to the parts worth seeing. The wheels stay, each turned to its true angle for the time, dimmed but left at their own colour, so gold still reads as gold. One thing does come off: the cage stands still overnight, so its seconds pointer would be frozen, and a frozen pointer goes on telling you the wrong seconds until morning.
Fenix and the other watches with a reflective screen instead of a glowing one get the whole thing again. Those panels have 64 colours and four levels of transparency, and the transparency is the harder of the two. A faint sheen wants a lot of in-between levels; with four it either vanishes or spreads into a smear. So the art is refitted to that palette, and the open background goes true black rather than warm, which is how a reflective screen looks.
8. Getting it onto the watch
The obvious way to ship a movement is to bake it into one flat picture. Small, instant to paint, and wrong: a wheel baked into the background is frozen forever, and even the slow wheels go round once an hour, so a watch you glanced at after lunch would be showing a machine that had not moved since breakfast.
So every wheel ships as its own sprite, turned to the angle the current time gives it. The slow ones take a new angle once a minute along with the rest of the face, which is how a watch face stays cheap to run. The fast ones take a new angle many times a second, and only while the movement is running, which is the few seconds after you raise your wrist.
In a ten-second wake the cage turns sixty degrees and the balance rocks back and forth four times a second, which is what the real thing does in ten seconds. The cage steps rather than glides, because the train is held between beats by the escapement. Everything on a mechanical watch steps like that; the seconds indication is only the one whose step is big enough to see. How long the movement runs is yours to set, with ten seconds, five seconds and off.
The faces this produced
Skeleton, sold on the store as Skeleton Tourbillon, puts the whole machine on show. Eleven wheels, each with the tooth count of a working calibre, and a flying tourbillon at six, carried from below with nothing bridging the top of the cage, whose pointer does duty as the seconds hand. On the Connect IQ store.
Regulator gives every hand an axis of its own. Hours on a ring in the upper half, minutes on the long central hand, seconds in a small dial at the bottom. That layout comes from the reference clocks on workshop walls, where the hands were kept apart so the long one could never hide another. On the Connect IQ store.
Skeleton Bridge stands the movement on one diagonal beam built like an engineering truss: a rail along the top, a rail along the bottom, a zigzag of struts between them. The two gauges beside it are mechanisms in their own right, each with a toothed rack, a pinion to move it and a marker riding a scale. The middle of the dial stays open, so the time is easy to read while the machine works around it. On the Connect IQ store.
Smoked Crystal is the newest. A tinted sapphire slab lies over the movement, and the wheels show through it at about a third of the contrast they have on their own, in the colour of the glass. The date and the weather are read through holes cut clean through the slab, which leaves them the only two things on the dial at full strength. On the Connect IQ store.
None of this is strictly necessary. I could draw a movement that looks about right and nobody would check the ratios. I work them out anyway, partly because the mistakes stay visible even when nobody can name them, and partly because a train that solves properly puts parts in places I would never have thought to put them. The fourth wheel decides where the small seconds go. I just draw what it decides.
Frequently asked questions
Does a skeleton watch face drain the Garmin battery?
Not these ones. At rest the face paints itself once a minute, the same as any well behaved face. The movement only runs after you raise your wrist, and you decide for how long: ten seconds, five seconds, or off. Once it stops, the dial costs what a still picture costs.
Does it work on a MIP Fenix?
Yes. The Fenix Solar models and the other watches with a reflective screen rather than a glowing one get their own version of the art, refitted to the 64 colours and the four levels of transparency those panels have. The wheels, the bridges and the jewels all survive down to the smallest screens. The open background goes true black there instead of warm, which is how a reflective screen looks.
Is the tourbillon real?
It is a drawing, and the drawing is driven by real gearing. The cage turns once a minute, which is what lets it double as the seconds indicator. The balance beats 28,800 an hour, eight beats a second, and the escape wheel advances one tooth every two beats. A watch screen has no moving parts. What is real is the arithmetic behind every angle you see.
Can I turn the animation off?
Yes. Every mechanical face has a setting for how long the movement keeps running after a wrist raise: ten seconds, five seconds, or off. Set it to off and you get the dial and the hands, and nothing spins.
The author builds the My Day 24 watch face family. Published 2026-09-08.