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·Clicks of Elgin production tools, might be of interest here:
Mechanical Watch Manufacturing Questions
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·Oh shucks!
You could have used Pee Wee Herman's line, 'I meant to do that!"
I would image trying too replicate an arrow shot into arrow would be extremley frustating to say the least.
You could have used Pee Wee Herman's line, 'I meant to do that!"
I would image trying too replicate an arrow shot into arrow would be extremley frustating to say the least.
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·Is it true or just legend:
The Amazon female archers would loop off their brest for better accuacy?
My wife said they did that mostly for the accuacy.
The Amazon female archers would loop off their brest for better accuacy?
My wife said they did that mostly for the accuacy.
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Archer
··Omega Qualified WatchmakerBased on the tolerances the holes are most likely reamed, but not honed.
Your observation regarding what would be acceptable for Statistical Process Control (SPC) limits in automotive compared to watchmaking actually doesn't surprise me. Nobody is going to die if a watch movement jams (except maybe James Bond?) I teach Tolerance Analysis in the medical device industry and one of the primary points I try to drive home for the young engineers is to always consider severity and detection in designing for manufacturability. An undesirable fit in an assembly, if undetected (and 100% inspection is NOT an effective detection method!), will result in some consequence that may be insignificant, or it may potentially result in patient harm.
It goes further than just the liability aspects...but also what is required to function...
I think the discussion about precision manufacturing in watchmaking tends to get a little skewed by the size of the parts. Yes, parts are small, but tolerances needed to make something work aren't necessarily as small in proportion to the size of the part. My previous engineering job was for a large multinational manufacturing company that made precision parts - being an American based company the dimensions we dealt with were not metric, but routine tolerances of 20-50 millionths of an inch were done in what was essentially commodity level mass production, making tens of thousands of parts per shift.
We had different divisions that made the same parts for true precision applications like military and aerospace - the parts I'm talking about just went in regular passenger cars, and they were still as tightly tolerances as anything I've seen for a watch movement, and the parts were thousands of time larger.
As you mention, the parts have to fit for the task, and although the parts are small, the clearances in a watch movement are actually quite large. This is difficult to illustrate easily, but I think think may give you an idea. This is a video taken through my microscope today of the end of a balance staff pivot in a running movement:
Now the diameter of that pivot is 8/100ths of a mm, but watch how the pivot slops around in the hole of the jewel. The clearance there isn't particularly tight from side to side (known in watchmaking as side shake).
The idea that watch manufacturing requires some very super tight tolerances just really isn't the case. Train wheels inside the watch all have similar side shake, and when you wind the mainspring and torque is applied, they all tilt to one side out of the vertical. This is expected and the watch still runs just fine. Watches are actually quite tolerant to this sort of thing - here is a watch pivot that is worn very heavily, but the watch was ticking when it arrived in my shop:
I won't say it was running well or anything, but it was still running. A host of pivots inside this watch were all worn, so this wasn't the only one. As long as the wheels don't tip enough to create severe binding, they will run, possibly with lower amplitude, but the watch will still function. In fact one of the things that allows watch movements like the cheap Seiko movements to basically run for decades without service, is that the tolerances aren't particularly tight.
These parts are not expensive either - typical train wheel for say an Omega 1120 or 2500 movement is about $18. They crank these out in vast quantities - they are not individually laboured over.
There was a watchmaker on another forum that used to drone on and on about watchmaking being the pinnacle of engineering and manufacturing over the centuries, but those days are long gone. It's far from being the level of precision that is required in other products.
BTW your comment on inspection not being an effective detection method is 100% true. That's why no one calls it quality control anymore, but quality assurance. Quality has to be designed in from the start of the design, right through the production process. 👍
Cheers, Al
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·It goes further than just the liability aspects...but also what is required to function...
I think the discussion about precision manufacturing in watchmaking tends to get a little skewed by the size of the parts. Yes, parts are small, but tolerances needed to make something work aren't necessarily as small in proportion to the size of the part. My previous engineering job was for a large multinational manufacturing company that made precision parts - being an American based company the dimensions we dealt with were not metric, but routine tolerances of 20-50 millionths of an inch were done in what was essentially commodity level mass production, making tens of thousands of parts per shift.
We had different divisions that made the same parts for true precision applications like military and aerospace - the parts I'm talking about just went in regular passenger cars, and they were still as tightly tolerances as anything I've seen for a watch movement, and the parts were thousands of time larger.
As you mention, the parts have to fit for the task, and although the parts are small, the clearances in a watch movement are actually quite large. This is difficult to illustrate easily, but I think think may give you an idea. This is a video taken through my microscope today of the end of a balance staff pivot in a running movement:
Now the diameter of that pivot is 8/100ths of a mm, but watch how the pivot slops around in the hole of the jewel. The clearance there isn't particularly tight from side to side (known in watchmaking as side shake).
The idea that watch manufacturing requires some very super tight tolerances just really isn't the case. Train wheels inside the watch all have similar side shake, and when you wind the mainspring and torque is applied, they all tilt to one side out of the vertical. This is expected and the watch still runs just fine. Watches are actually quite tolerant to this sort of thing - here is a watch pivot that is worn very heavily, but the watch was ticking when it arrived in my shop:
I won't say it was running well or anything, but it was still running. A host of pivots inside this watch were all worn, so this wasn't the only one. As long as the wheels don't tip enough to create severe binding, they will run, possibly with lower amplitude, but the watch will still function. In fact one of the things that allows watch movements like the cheap Seiko movements to basically run for decades without service, is that the tolerances aren't particularly tight.
These parts are not expensive either - typical train wheel for say an Omega 1120 or 2500 movement is about $18. They crank these out in vast quantities - they are not individually laboured over.
There was a watchmaker on another forum that used to drone on and on about watchmaking being the pinnacle of engineering and manufacturing over the centuries, but those days are long gone. It's far from being the level of precision that is required in other products.
BTW your comment on inspection not being an effective detection method is 100% true. That's why no one calls it quality control anymore, but quality assurance. Quality has to be designed in from the start of the design, right through the production process. 👍
Cheers, Al
I get the basics on tolorances, and what you are saying.
Could not agree more.
Watchmaking did was a builing block for almost everthing today....
The massprodution lines prety much started in this field.
Actually pen making, ? Adam Smith English.
With the advent of microprocessor [ Chips ] alone, is mind bogaling.
You see the resolution per mm in the lenses needed to make them is wild.
The used lenses show up from time to time & that's out dated to current production.
Hey, Al , another 50 years & what's the diffence. Old Tymers would say at work.....
What really baffeled me is the diameter of the jewel hole to the pivot on Rolex watches, under a loop it look like a pen in a pen holder.
Mike
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·Al, good vid on the pivot.
I remeber a Rolex 3135 balance, where that would have been a nice differential jewel hole to pivot diameter.
I could not at first figure out why it was hard to feel end travel. Took a closer look with a loop & it appeared like the end of a childs toy gyro or top floating around. When finally adjusted, it kept a good rate. With balance wheels, as long as the roller table transfers motion, guess all is good. Here is the kicker on balance wheel pivots.
The bottom of the pivot needs to be about the same surface area of the friction area applied to pivot. So as jewel is not a roller bearing, the balance wheel pivot with the wheel vertical has a very minute surface contact.
With the wheel in the horizontal, the friction is on the bottom pivot, which in theory should be equal.
So too much of a dome runs a gain, too flat, a slow rate.
? Me this one, Batman: how in the world do they actually calculate this out.
Then there is the pivots are actually hydroplaning in the oil to boot.
A general comment is ok, as I would not understand any great mathmatical formulas.
It isn't any fun if we can't joke about it......
as a co-worker put it, "Why me Lord, what did I do to deserve this?"
As you know, put enough power in it and anything will fly.
Lose internet for a while after the morrow.
Take care,
Mike.
I remeber a Rolex 3135 balance, where that would have been a nice differential jewel hole to pivot diameter.
I could not at first figure out why it was hard to feel end travel. Took a closer look with a loop & it appeared like the end of a childs toy gyro or top floating around. When finally adjusted, it kept a good rate. With balance wheels, as long as the roller table transfers motion, guess all is good. Here is the kicker on balance wheel pivots.
The bottom of the pivot needs to be about the same surface area of the friction area applied to pivot. So as jewel is not a roller bearing, the balance wheel pivot with the wheel vertical has a very minute surface contact.
With the wheel in the horizontal, the friction is on the bottom pivot, which in theory should be equal.
So too much of a dome runs a gain, too flat, a slow rate.
? Me this one, Batman: how in the world do they actually calculate this out.
Then there is the pivots are actually hydroplaning in the oil to boot.
A general comment is ok, as I would not understand any great mathmatical formulas.
It isn't any fun if we can't joke about it......
as a co-worker put it, "Why me Lord, what did I do to deserve this?"As you know, put enough power in it and anything will fly.
Lose internet for a while after the morrow.
Take care,
Mike.
