Tuesday, September 30, 2008

Is your tool watch decreasing your mental agility?

Occasionally, it's nice to wear a high-quality vintage watch. It tells the time and nothing else. So any activities to do with time required some mental effort, maybe even a little mental arithmetic in the form of base 60 addition or subtraction. Such effort is good exercise for the mind, thereby keeping it in good condition.

The other day, I was wearing this beautiful watch:

1920's Elgin
(more pictures here).

Suddenly, my dear wife wanted to be reminded of something in 55 minutes' time. Without thinking. I rushed to my collection, strapped this one on and set the count-down timer accordingly. Didn't even have to think about it. 55 minutes later, sure enough it beeped. "Why is this watch beeping?", I asked. Duh!

2004 Citizen Wingman
(see more tool watches here).

When I think back to my youth, "55 minutes" was about an hour, something easily handled by the mind and confirmed by a couple of glances at the Elgin or whatever. The seconds hand's main duty was to confirm that your watch was running. At school, we learned our multiplication tables by rote up to 12x and we also learned how to do long division on the back of a fag packet. Those were the days when shopkeepers and counter clerks added up long columns of figures on sales receipts and general ledgers with nary a calculator in sight. Discounts or markups were figured mentally.

I would say that progress in the tools of mankind, not just watches, has reduced our mental agility quite considerably. What say you?

Best regards,


Wednesday, July 30, 2008

Review of a Cheap Watch

I've read a lot of reviews of quite expensive or rare watches. But sometimes a cheapie comes along that represents an awesome value for money. One of my many watches was bought on eBay when it's auction was just about to close at $2.99 and no bids. $2.99??!!! I just couldn't resist snapping it up! SWMBO took a liking to it, and I've just installed it's second battery. Seems like it was part of a promotion for Time Magazine. Here it is:

Nice 32mm diameter steel case with a large-ish 25mm black dial. The dial sports 24-hr numerals and luminous 1-12 hour numerals. The obligatory "Mercedes" hands, a la Explorer, are also luminous. As you can see below, the "Time" logo is in the same font as the well-known magazine cover:

Moving on, it came with nice strap and the back proudly declared it to have a "JAPAN MOVT":

I think it's a PC21, the three-hands version of the incredibly prolific PC20. Otto Frei is currently selling PC21's for $4.95, should I ever need one. These little movements, far removed from the revered ETA/ESA offerings, are remarkably reliable and accurate for what they are - the electronic version of the Timex model 24.

The padded leather strap is unashamedly of oriental original, with "CHINA" stamped all over it. It tapers from 17mm at the lugs down to 14mm at the buckle:

The buckle design, with the flattened part where the tang rests, is highly resistant to opening up - so the loss of the 14mm spring bar is most unlikely.

Nice chunky lugs maintain a sporty look. The flat mineral glass crystal is un-scratched (so far ;-) The crown doesn't look original to the watch though, it sticks out too far and is the wrong color. I have a good few of those same "LP" generic crowns in my bits box.

This is one of my dear Wife's favorite watches for casual wear. The sizeable dial and markings are most suitable for her eyesight as opposed to those lady's tiny vintage watches so commonly found on eBay.

Best regards,


Friday, May 30, 2008

My ideal rotating Bezel

I prefer hours - good for other time zones, like eBay, or for living by solar time with one eye on the real world. But, on the other hand, I often need to time something in minutes. I also find that uni-directional bezels are a pain because I don't actually scuba-dive daily. And how do you set half-hours on a 60-clicker?

So, in my mind, I just bought this SandYathon:

The bezel would be narrower of course, but you get the idea. Mine would probably not have clicks but, if it did, it would have 120, not 60. Being a little old-fashioned, the hours would be subdivided into halves and fourths. The minute divisions would go all the way around as shown. Maybe the hour numerals would be Roman to readily distinguish them from the minutes. It could look quite good and nowhere near as cumbersome as the above creation.

For example, this Jupiter Pilot has two scales on a really narrow bezel and is still quite readable:

Best regards,


Thursday, May 29, 2008

Sexagesimal Time

Old measure wasn't much of a problem BC (before computers). We mixed together all kinds of units and bases but we were quite used to them. The Brits coped quite admirably with pounds, shillings, pence and even the occasional sovereign up until the early 70's when Heath took them kicking and screaming into the E.U., or EEC as it was known back then. To this day, Americans still struggle on bravely with tons, pounds, ounces and grains in everyday life - not to mention gallons, pints and fl. ounces!

Although most countries are metricated now, the time of day has remained supremely sexagesimal to this very day. The time of day is represented as hh:mm:ss. This format is based on the Babylonian positional numbering system, with colons separating the positions. The Babylonians inherited sexagesimal counting from the Sumerians and improved the system by adding positional significance (by powers of 60) and the concept of the number zero. They still used chicken-scratchin's (cuneiform) to represent the values of each position and each value was represented in base 10 notation using a grouping of the two symbols for one and ten. This symbol grouping was not itself positional and so simple addition gave the value, see table below. For example 23 is represented by 2 eyeballs and 3 wine-glasses, i.e. 2x10 + 3x1 = 23.

Because the number of hours in a day is less than 60 (on this planet, anyway) our time-of-day representation is truly sexagesimal and follows the Babylonian system with the addition of colons as separators and the use of Arabic numerals instead of cuneiform.

There is an interesting property of the hh:mm representation. It is either a fraction or an integer number depending on how you look at it, but the representation itself does not change. For example, let's say a timer shows a elapsed time of 3 hours and 40 minutes, which is written as "3:40". In our decimal system (i.e. positional base 10), that would be 3.667 hours or 220 minutes. In sexagesimal, 3:40 represents either 3x60^0+40x60^-1 hours or 3x60^1+40x60^0 minutes but the bolded numbers do not change and the colon remains where it's at.

But what if there were more than 59 hours involved, for example three days, 13 hours 43 minutes and 22 seconds? "Easy!", you say, "just write 85:43:22" - but sorry, that is not a true sexagesimal number because 85 is more than 59! To be truly "sexy", it would have to be written 1:25:43:22 which is 1x60^1+25x60^0+43x60^-1+22x60^-2 and which is also thoroughly confusing! Indeed, this is why we still have a DMS function (angular Degrees, Minutes and Seconds) on our engineering calculators due to the mixed bases of decimal degrees with sexagesimal minutes and seconds.

Best regards,


Wednesday, May 28, 2008

Unusual Hamilton GG-W-113 bridge

I've serviced a good few Hamilton GG-W-113's over the past year and have become accustomed to various engraving styles used to designate their 17-jewel Cal. 649 ebauche ETA 2750. Some are even marked "seventeen 17 jewels unadjusted" with no mention at all of "H W Co Inc" & "649".

But, until today, I've never seen this style - the movement is from a one-piece case model dated May 1982:

hammy bridge
close up

The turned circle is about 2.4 mm dia, just under 1/10" !! The inked (?) lettering is not real sharp.


What time is it (historically speaking)?

Let's say it's about half-way through the morning, our 10:00 hrs.

Well, we all know that AM is short for ante meridiem i.e. Latin for "before noon". But did you know that the Romans said it literally, i.e. "10 AM" meant ten hours before noon, i.e. our 02:00 hrs?

Not content with that confusion, their descendants decided to start the day at sunset - so half-way through the morning back then, their stupid clock would show somewhere between 15 o'clock and 16 o'clock!

This one, with its markers in the middle of the hour, would show exactly 15 o'clock.

And then there's "noon" which comes from medieval Church time, and was originally our 3 PM!
The Church started it's day at dawn, prime being the first hour, and said prayers every three hours more or less. However, the monks weren't allowed to eat before none the ninth hour, so they reduced the intervals between prayers until "nones" were said just after midday. Hence, our "noon" comes from the ninth hour of the Church day.

Best regards,


Sunday, May 25, 2008

UV-excited lume shots

Having recently purchased a 38-LED 2-Watt UV lamp, I decided to take some lume shots. UV light is best for charging photo-luminescent paint, see my article on watch lume. Here's the set-up:

the setup

When I switched on the lamp, the watch lume glowed like it was on fire!! However, the first shot was a little disappointing and there seemed to be no camera setting that brought out the brightness. It seemed that the UV itself was messing up the shot by over-exposing the camera sensor in spite of the UV filter on the lens:

first try

So, I tried charging up the lume and then switching off the UV lamp before taking the shot. I ended up with 5 seconds exposure at f/22; consequently, much of that prized initial brightness was lost (f/22 is my standard aperture setting - I leave it there for a good depth field from the 60mm macro lens). Had I shot at say f/8 for a shorter time, the lume would have come out brighter. Still, even at f/22, the resulting pictures came out well and were combined in Photoshop without any processing other than cropping and re-sizing.

A re-lumed 1900's Trench watch:
trench watch

A re-lumed Hamilton GG-W-113:
113 leftie

A Hamilton MIL-W-46374D with replacement Luminova hands:
Hamilton with Khaki hands

In the last shot, the lumed seconds hand sweeps through the 5 secs exposure and the rapid fall in brightness of Luminova, even during that short time, is quite evident.

Best regards,


Saturday, May 24, 2008

Review of a Broken Watch

Hi All,

This 1981 watch sits on my work bench all the time. The only functions that work correctly on it are the chronograph and the countdown timer.

Here it is, in all it's glory!

bench navihawk

It was quite a fancy watch in it's day. 60g of heft, 20mm lugs, 13mm thick and a 41mm slide-rule bezel. It sports gold trim on the bezel, gold pushers, a white dial and the well-known Citizen C300 movement. This movement has a common fault: everything seems fine until you pull out the bottom right-hand pusher to reset the watch after a battery change or to change between regular and summer time. Nothing happens. The contact inside the movement has failed. However, the chronograph function is unaffected (nothing to set) and is perfect for watch regulating with it's 24 hr capacity, 1/100 sec resolution and especially the "split time" feature. The split time feature lets you check the regulation after a few minutes of running without stopping the chrono - this gives you an early check on the goodness of the regulation. The slide rule bezel still works smoothly and I do use it to calculate the daily rate of a watch. Here's how:


Assume that the watch ran for 60 minutes and the split time measurement said the the watch was off by 0.85 sec. Realistically, this means somewhere between say 0.8 and 0.9 secs (accounting for human reaction time). Set 1440 (the number of minutes in a day) on the outer scale next to 60 (minutes elapsed for this example) on the inner, like so:

timed over 60 mins


Look for 0.8 to 0.9 (secs error) on the inner scale. On the outer scale, we see that this corresponds to between about 19 and 22 secs per day error.

19-22 secs/day

For me this watch is akin to my trusty Wenger pocket knife, and I'd be quite put out if it died on me!

Best regards,


More Oil Migration

It was so fascinating to see those stress patterns that I just had to play a little more. This time, the goal was to simulate the gap between a cap and a pivot jewel such as found on a balance cock. The top of a pivot jewel is slightly curved and the bottom of a cap is flat. When oiling balance pivots, the goal is to provide sufficient oil to form a ring of oil around the end of the pivot between the jewels.

Another blob of motor oil was placed between the crystals not far from the middle and two clothes pins provided the necessary fringe pattern to simulate the juxtaposition of a flat surface and a curved surface. Sure enough, the blob headed for the thinnest gap - albeit very slowly, The pics below show the position after 6 hours elapsed time (that radial shadow line is a deep scratch outside on one of the crystals):
oil blob
oil blob

It appears that there comes a point where the blob stops moving, since it did not go all the way to the center. This point is likely when the molecular attraction force between the oil and the surface of the glass is equal to the motion force that is due to the decreasing gap (or gap force gradient). When the gap decreases the oil spreads out, thereby increasing the attraction force between the oil and the surface. Also when the fringe lines are wider, the gap gradient is smaller.

These experiments have shown quite conclusively that oil tends to move to the narrowest gap and stay there. So fears of random oil migration if a watch is left in drawer are groundless. By the same token, running a watch occasionally to "spread the oil around" is a waste of time IMHO. Also, since the oil moves as a blob, insufficient oiling will leave dry zones - not a good thing.

Sorry about the terminology, I never really studied capillary action or tribology for that matter!

Best regards,


Friday, May 23, 2008

Oil Migration - Moebius vs. Mobil

Oiling a watch movement is serious business. If you use the wrong oil, there's plenty of people out there to wag their finger at you and say "I told you so!". On the other hand, Swiss watch oil is pretty expensive and some might be tempted to seek alternatives.

On a whim, I decided to compare Swiss watch oil with automotive synthetic oil. After all, motor oil is designed for a much harsher environment than the inside of a watch. I took two flat glass 30mm watch crystals, cleaned them with alcohol and held them together with a small plastic clothes pin. Using a watch oiler, I put 1 'measure' of the following oils at the edge where the crystals were touching - a slight chamfer on the edges formed a convenient 'V' to touch the oiler to.

Mobil 1 5W/30 synthetic motor oil (upper)
Moebius 9010/2 sythetic light train oil (middle)
Moebius 941 synthetic pallet jewel/escape teeth oil (lower)

I was completely unprepared for the result!

As I touched the oiler to the edge of the crystals, I noticed that, not unexpectedly, each oil blob moved inward a little, leaving no oil at the edge. I noticed also that an optical fringe effect was actually indicating the interfacial stress caused by the clothes pin pressure. "Must take pictures!", I thought. While I was setting up the camera, I noticed that the motor oil seemed to have changed shape and moved a bit!. As you can see from the above shots - it eventually moved a lot, disappearing under the clothes pin in less than an hour!! The first shots were a couple minutes apart; the last four were taken at 5, 10, 15 and 60 minutes elapsed time.

The motor oil moved in the direction it did because the attractive molecular forces were greater on the side nearer to the clothes pin. Attractive forces are higher when two surfaces are closer together as shown by lower spatial frequency of the fringe pattern toward the pin. However, the blob stayed essentially whole because of it's own surface tension except where some some surface irregularity caused it to shed a small piece (conflicting attractive forces exceeded the shear strength of the oil).

I conclude that Swiss oil does tend to stay in place as advertised, and that oil can migrate away from where you put it - leaving dry, un-lubricated areas if the forces of capillary action so dictate, or if you just don't put enough.

I have to say that this is an astounding sequence of photos, made alive by the wonders of today's Internet technology. Do forgive me if I sound a little immodest!

Best regards,


Saturday, March 29, 2008

Time Zone Tyranny - fight back!

In the past, humans arose with the Sun, went to work (with perhaps a break for lunch at noon) and quit their labors at Sundown. All very natural.

Then came clocks with equal hours followed by minutes and finally seconds. Now we have to have the most accurate watch possible in order to keep in sync with what could be called "civil time" complete with timezones and the changing of the clocks twice a year.

Spare a moment of pity for those unfortunates who live in Van Horn, West Texas, a city at almost 105 degrees West, but on Central Time. They're already an hour "fast" in winter but in early March they change to Daylight Savings time plus the Equation of Time causes their time-pieces to be about a quarter of an hour even faster with reference to the Sun. All this means that, at high noon in Van Horn, their time-pieces say 2:15 pm!!

Now if you're retired or currently "resting" you can fight back and lead a more natural life. Here's how:

Go and buy a watch with a rotating 12-hour bezel. (Hey, we always need another watch - this time for health reasons ;-). Spend some time Googling to find out how far off civil time is at your home. Then, for those in the West: turn the bezel back by that many hours; Eastern folks would turn it forward. Then set the watch to local solar time. If you've got it right, the sun should be overhead at 12 o/c. If you ever have cause to know civil time, just look where the hour hand points to on the bezel (ignore the minute hand).

I'm trying it out on this P650 . .

P650 in solar time mode

Katy, Texas is at almost 96 degs West. With our wobbly planet in it's elliptical orbit, the sun is overhead at 13:23 civil time this week, ie an hour and 23 minutes fast. The pic was taken at about 9:30 pm CDT and the local solar time is 8.08 pm.

Best regards,


Sunday, February 3, 2008

Meters, Bars , Atms and Water Resistance

Our "tool" watches usually have a water resistance rating marked on them somewhere. The term "water resistance" is the liberal, politically correct version of the older and proudly unambiguous "water-proof". The rating is usually marked in meters - but it never says what kind of fluid those meters represent. Certainly, if I plunged my watch 200 meters deep into a pool of mercury I would expect something nasty to happen. However, we can safely assume that the Makers do mean water by the implication of references to swimming, diving, showering, etc. Other popular units of rating are "bars" or "atmospheres". All of these units are slightly different to each other, that is to say 10 bar is not exactly 10 atm. Similarly, 100m of seawater exerts a different pressure than 100m of fresh water. Here's a handy little table for those who just have to know.

water table ;-)

It's used horizontally (stand up, fool!). Use the bold figures and go left or right to see the equivalents. For example, 10 bar is 99.291m of seawater. If yours is 20 bar then multiply the equivalent by 20/10, i.e. 2 x 99.291 = 198.58m. Divide by 0.3048 to get feet from meters . . 198.58/0.3048 = 652ft.

It looks like a watch rated in ATM is the most "water resistant" in theory but I have to say that, after taking some time to research and create this fine little table, I find it to be virtually useless! It's useless because it doesn't help anybody in the real world. In the real world, watches do not implode or flood with water as soon as the rating depth is exceeded, any more than Tritium lume becomes completely invisible exactly 12.33 years after it was made. Now warranties are a different matter, somewhat akin to falling buttered toast!

Best regards,


Tuesday, January 29, 2008

Explosive Decompression

So, there you are, cruising along at 36,000 feet and the cabin door blows out. Will your watch crystal pop out or not? Would you really care? If so, read on . . .

The force on the crystal is the pressure differential between the outside and inside of the watch, multiplied by the area of the crystal.

Most planes are pressurized inside to about the equivalent of 8,000 feet and airliners fly at around 36,000 feet, so therein lies the pressure difference which is about 52700 Pascals. See here for an ICAO standard atmosphere calculator.

My Gallet Navigator's watch, for example, has a crystal of 30 mm diameter.

I figure the force to be 37 Newtons or 3.8 kg or 8.4 lb. Not a lot, really. Therefore it's probable that the crystal will stay in place, although your ears won't be up to much for a while!

best regards,


Friday, January 25, 2008

Rate your Collection the Geeky way!

When you've collected more than a few watches, there comes a time when you want sell one or two - or you're unsure which ones to keep.  You look at one and you want to keep it but it's lume is poor - or this other one keeps perfect time but it's ugly, etc, etc.  Then, when you've looked at them all, you have to remember what you thought about each one.  There is also a problem for many folks in actually organizing their thinking in such matters especially at my age!  However, the world of programming provides a possible solution to organizing your thoughts and spreadsheeting can provide the memory and even rank your collection!

Without going into it too deeply, modern programmimg relies heavily on objects, properties of objects, and values of those properties.  If we take "watches" as a class of objects, then we could define an object in that class as an "ana-digi".  Now, having chosen analog-digital watches to think about, we would then decide what properties of analog-digital watches are important to a collection.  Those properties are your choice, but I would choose something like "form, function, condition & value".  After deciding what these named properties represent, you can rate each of your watches by giving a score to each property and then adding them up.  The one with the least points would be the first to go if you were culling the collection.

Co-incidentally, it happens that I own several "instances" of ana-digi watches - a Breitling and various Citizens.  So I tried the concept out in a spreadsheet.  Unfortunately, it didn't really seem to give realistic results.  The Breitling came out last, and that's not really what I would do.  It came last because of it's ugliness (the form property) and it's a bit beaten up (the condition property).  I realized that the concept itself was a little too simple.  In the spreadsheet, each property had equal weight - whereas, when considering tool watches such as these, surely function carries more weight than form or condition?

So, back at the spreadsheet, each property was assigned a weighting factor.  Now, changing the condition of a watch had less effect than changing the function and, lo, reasonable results were obtained.  Here is the sorted result:

ranking table

"A lot trouble for only three watches", you might say and I agree.  But there are folks with twenty or more diver's watches - what if Wifey says "you can't buy any more unless you sell a few?".  If you would like to download the spreadsheet to play with, I've posted it here.

Best regards,


Tuesday, January 22, 2008

The most precious watch metal

Many people think that the most precious metal available in a wristwatch would be platinum or possibly palladium. Surprisingly, that is incorrect. The most precious metal found in watches is probably staring up at you as you glance at the time. I refer to rhodium - often used to impart a good shine to watch hands or dial markers because of it's high reflectance. There's quite a good article on rhodium as it relates to jewelry here.

Today's (1/22/2008) prices for precious metals tell the tale . . .

Best regards,