Mechanical Watch Manufacturing Questions

64Wing

Hey Bob (if that is your real name...which some part of me recalls it is NOT! lol)

I highly recommend you check out this YouTube channel. The dude decided to make his own mechanical watch from scratch...and I really mean from scratch.

https://youtube.com/c/DeanDK

PS: I would think that a good foundation in automation could be very useful in the production of several parts. But nothing can replace good, old-fashioned know how with a hand tool.

I'd be very interested to see you chronicle such an endeavor!

64Wing

I dig, man!

Strange enough, my cousin's husband is a device salesman. Or whatever you call someone that scrubs in to supervise the installation of a joint or artificial tendon etc. Couldn't tell you what company he represents, but he's the best in his field here in the Midwest.

You know, if you've got experience in machining tough materials like what they make joints out of, you might consider dabbling in some DOD stuff...

Dan S

My mom had a TAVR procedure, which sounds similar to what you work on. I think hers is Medtronic.

Bob Neville

I wasn't sure what Forum to drop this in, so here it is. I've been working in/around high-precision machining most of my career. As a young engineer right out of school my first employer put me out on the shop floor and ran me through a CNC mill and lathe apprenticeship. I programmed, set-up, and ran CNC mills and lathes for a couple of years. I love the smell of a machine shop, and my goal after I retire is to find a part-time job at a shop - they can pay me minimum wage. Anyway, being new to the watch collecting hobby, I'd love to learn details about the manufacturing of mechanical watches. Although I've never programmed a screw machine (neither cam-type nor G&M code), I have done some prototyping on one (manufactured by Tornos), and I've done a ton of research on Marubeni-Citizen. One of my areas of expertise as an engineer is design for manufacturability (DFM), so tolerancing is interesting to me. I would wager that in the movement the escapement components and assembly probably have the tightest tolerances relative to the rest of the movement. My guess is that component and assembly features like the distance from the fulcrum to the yoke on the pallet fork, the radial distance from the center of the balance wheel to the timing pin on the balance wheel, and the radial distance from the center of the escapement wheel to the ends of its respective teeth would require some of the tightest tolerances in the movement assembly. I'm guessing probably +/-0.010mm on component features and maybe +/-0.025mm on assembly features (accounting for tolerance stack-ups). Am I in the ball park?

Archer

Putting on my engineering hat for a moment...you are confusing dimensions with tolerances.

So what's the difference? In manufacturing, dimensions are free, but tolerances cost money. The tighter the tolerance, the more money it costs to produce the part or product.

Since this isn't a mechanical engineering forum, I'll skip things like geometric tolerancing and just stick with the very simple form of tolerancing that some may be familiar with.

So in your example you are using end shake - for those not familiar with the term this would typically be called end play outside of the watch world. In a watch it defines amount of vertical movement that a wheel can make between the two jewels or bushings. I talk about checking and adjusting this in one of the watchmaking tips series I've posted here:

Basic Watchmaking tips - checking and adjusting end shake | Omega Forums

This is only one aspect of the tolerances that the OP is asking about, but it would be a good place to illustrate the difference between a dimension and a tolerance for those who might not be 100% clear on this.

Looking at a Speedmater 1861 movement, the end shake requirement on the third wheel is 0.04 mm. But that is the target dimension, not the tolerance. The tolerance on this end shake is +/- 0.02 mm. So the range that the end shake can be and still be acceptable is 0.02 to 0.06 mm.

So when you quote the end shake requirement being 0.02 mm on the escape wheel, that is the dimension but it doesn't speak to the tolerance.

So another example is the balance wheel end shake on the Speedmaster 1861. The dimension is 0.0225 mm, and the tolerance is +/- 0.0075 mm. Meaning that the acceptable range of end shake is between 0.015 and 0.03 mm.

Regarding the dimensional tolerances of manufactured parts, this is not information that watch companies readily release to even watchmakers doing service work. So I'll do a little digging and maybe some measuring to see what I can come up with to help answer this.

Cheers, Al

Out of TIME!

After posting, I remebered a great book that is great on chonometers & I belive may answer more your ?
George Daniels, English chap, passed in 2011.
The Co-axial Escapement is his Baby.
Cheers! Mike

Out of TIME!

You have the basics, from the mainspring barrel, center wheel, [ Itermeadiate Wheel ] tolleraces are dependant on the grade of the movement, a little more loose.
When you get to the fourth wheel, and escape wheel they get tighter.
For more stability, the escape wheel, pallet, & the balance wheel get tighter about 0.02mm end shake.
This is the purpose of cap jewels also. Limit end shake & keep the lubrication in place. More or less!
The old watch school courses have a ton of information on drawing escape wheels, pallets....
YouTube video to take in, "Tour Glasshute Original Factory". Watch & listen to the Dutchman giving the tour.
I could watch that sevearl times over it is sooo fasinating.
You will see CNC machining & watch finishing at it's finest.
Cheers Mike
Maybe Archer could add comment also.

Archer

Putting on my engineering hat for a moment...you are confusing dimensions with tolerances.

So what's the difference? In manufacturing, dimensions are free, but tolerances cost money. The tighter the tolerance, the more money it costs to produce the part or product.

Since this isn't a mechanical engineering forum, I'll skip things like geometric tolerancing and just stick with the very simple form of tolerancing that some may be familiar with.

So in your example you are using end shake - for those not familiar with the term this would typically be called end play outside of the watch world. In a watch it defines amount of vertical movement that a wheel can make between the two jewels or bushings. I talk about checking and adjusting this in one of the watchmaking tips series I've posted here:

Basic Watchmaking tips - checking and adjusting end shake | Omega Forums

This is only one aspect of the tolerances that the OP is asking about, but it would be a good place to illustrate the difference between a dimension and a tolerance for those who might not be 100% clear on this.

Looking at a Speedmater 1861 movement, the end shake requirement on the third wheel is 0.04 mm. But that is the target dimension, not the tolerance. The tolerance on this end shake is +/- 0.02 mm. So the range that the end shake can be and still be acceptable is 0.02 to 0.06 mm.

So when you quote the end shake requirement being 0.02 mm on the escape wheel, that is the dimension but it doesn't speak to the tolerance.

So another example is the balance wheel end shake on the Speedmaster 1861. The dimension is 0.0225 mm, and the tolerance is +/- 0.0075 mm. Meaning that the acceptable range of end shake is between 0.015 and 0.03 mm.

Regarding the dimensional tolerances of manufactured parts, this is not information that watch companies readily release to even watchmakers doing service work. So I'll do a little digging and maybe some measuring to see what I can come up with to help answer this.

Cheers, Al

Bob Neville

I watched that YouTube Glasshaute factory video - really cool stuff. They use everything from precision benchtop machines to wire EDM to CNC mills, and I even saw an old-school cam-drive traditional Swiss screw machine. One of the processes, I think it was the finish burnishing on pinions, the narrator said they hold a tolerance of 0.003mm - that's insane. Some people try to provide folks unfamiliar with precision machining a sense of proportions by comparing to the human hair, but hair thickness is actually really variable. What I like to use is the thickness of a sheet of paper. A typical sheet of copier paper is around 0.080mm thick (the heavier stuff may be up to around 0.100mm thick). So now imagine that this process they're repeating to 0.003mm (even if it's +/-0.003mm) is like 1/30th (or even 1/15th) the thickness of a sheet of paper. I used to work on a CNC grinding machine that used glass scales and lasers to repeat axis locations to 0.0002mm (and no, I did not accidentally add an extra zero there - that's two one-thousandths of a millimeter axis locational repeatability). But it didn't mean product repeated to that because there was more variability just in tool wear, workpiece material variability, natural vibrations, and even just temperature fluctuations in the flood coolant, ...but at least I never had to worry about locational repeatability.

Bob Neville

I watched that YouTube Glasshaute factory video - really cool stuff. They use everything from precision benchtop machines to wire EDM to CNC mills, and I even saw an old-school cam-drive traditional Swiss screw machine. One of the processes, I think it was the finish burnishing on pinions, the narrator said they hold a tolerance of 0.003mm - that's insane. Some people try to provide folks unfamiliar with precision machining a sense of proportions by comparing to the human hair, but hair thickness is actually really variable. What I like to use is the thickness of a sheet of paper. A typical sheet of copier paper is around 0.080mm thick (the heavier stuff may be up to around 0.100mm thick). So now imagine that this process they're repeating to 0.003mm (even if it's +/-0.003mm) is like 1/30th (or even 1/15th) the thickness of a sheet of paper. I used to work on a CNC grinding machine that used glass scales and lasers to repeat axis locations to 0.0002mm (and no, I did not accidentally add an extra zero there - that's two one-thousandths of a millimeter axis locational repeatability). But it didn't mean product repeated to that because there was more variability just in tool wear, workpiece material variability, natural vibrations, and even just temperature fluctuations in the flood coolant, ...but at least I never had to worry about locational repeatability.