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#1 |
TRF Moderator & 2024 DATE-JUST41 Patron
Join Date: May 2007
Real Name: Larry
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Reading Your Bezel......Tachymetre/Telemeter
The Tachymeter or Tachometer bezel on your Chronograph is a simple calculator for determining approximate speed in MPH/KPH, or determining a simple rate of production.
For speed estimates, you need a measured mile or kilometer. As the object you want to time enters one point on the measure (milepost) start the stopwatch function of your chronograph. When it reaches the next milepost, stop the second hand. An estimate of mph is read off the bezel. Here is an example. The time to travel the measured mile took 20.2 seconds or ~179 mph SpeedyTachy-1.jpg Rate of production can also be determined. If you are watching an assembly line, or timing an event (say chugging a bottle of water), you start the timer at the beginning of the event. You stop after the end of the event, or when another product comes off the assembly line. Using our example above; if 1 widget was made during the 20 seconds timed, then 179 widgets are being produced per hour. Or you are chugging a bottle of water at the rate of 179 bottles per hour. There are more than one type of bezel or scale available for a chronograph. Some are marked with a Telemeter bezel. In the case of our next example below, it is the red scale. When a visual cue at a distance is observed, the timer is started. The timer is stopped when an audible cue that corresponds to the observation is heard. The approximate distance is read off the scale. Using our example below let's say that a lightning strike is observed, and then the event is timed until the thunderclap is heard. In this case, ~36 seconds, and our scale is calibrated in kilometers, so reading off the telemeter scale, distance is slightly over 12 kilometers away. In a military application, you can see the flash of the artillary, time the event until you hear the sound, and be able to know the approximate distance away the artillary is placed. LancoTachy-1.jpg One last type of bezel encountered is the decimal bezel. This is easily identified because it is calibrated from 1 to 100, Using this bezel, time is read off the bezel in tenths, or hundreds of a minute.. If you time an event and the second hand is stopped at exactly 30 seconds, the decimal bezel would reflect .50 of a minute.
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(Chill ... It's just a watch Forum.....) NAWCC Member Last edited by Tools; 19 February 2020 at 10:09 AM.. |
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#2 |
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Real Name: juneja
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#3 |
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Excellent post, Larry. Thank you.
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#4 |
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Real Name: Simon
Location: UK
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Another great article, and very useful too but aren't we forgetting another member of the Speedy bezel family?
Here's my 1967 cal 321 Speedy with a Pulsations or Doctor's bezel. It is used to measure heart-rate by recording the time it takes for 15 heart-beats. The watch is stopped after the 15th beat and the equivalent BPM is displayed. What do you reckon to this one? Cheers - Simon ![]() |
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#5 |
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Real Name: yuji
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nice information!
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#6 |
TRF Moderator & 2024 DATE-JUST41 Patron
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Real Name: Larry
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Omega also produced a Decimal bezel for the Speedy as shown in this 1970 example.
This bezel was handy if you were interested in knowing hundredths of a minute.. For example; 15 seconds would be 25 hundredths of a minute, or in the case of this photo, the second hand is stopped at 22 seconds, which equals 37 hundredths of a minute. Speedy Decimal.jpg ![]()
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#7 |
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My vintage Speedy Pro manual provides this info regarding all four bezels:
![]() ![]() The telemetric bezel was used as an artillery range finder. The chrono hand was started upon a muzzle flash and stopped when the shot was heard. The scale then revealed the range. Fr. John+ |
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#8 |
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This is a very interesting and informative thread! Thanks guys! Cheers, Bill P.
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#9 |
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Hi Larry
Great posting and info. I have been wondering how it all worked Si ![]() |
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#10 |
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All very good and informative information, Guys. Thanks for posting.
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#11 |
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good info.. thx
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#12 |
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I never even thought about using Tachymetre. For me, it was always about the look-factor. But great article, I learned a few things just then.
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#13 |
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Good thread. I have learned something today.
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#14 |
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thanks for sharing
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#15 |
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Thanks for the post and info, always wanted to know!
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#16 |
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Thank you Larry....as always!!!
You never let us down ![]() |
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#17 |
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I went to Jared's yesterday to look at them first hand. I was very impressed with Omega and they felt solid. I used the chrono function for the first time while shopping and I knew how to use the bezel.
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#18 | |
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Quote:
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#19 |
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Useful information. Thanks
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#20 |
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The telemetric bezel appears to be a useful tool to use when you're in need of it.
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#21 |
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Excellent post !
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#22 |
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Real Name: Eric
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Great posts - never thought of it in terms of manufacturing product - which is what I do!!! Duh.... Now I don't have to use my cell phone.... lol....
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#23 |
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I am embarrassed to say, I have owned 2 Daytona's & had no idea what the bezel was used for... now I know, thanx!!!
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#24 | |
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Heart Rate Readings
Quote:
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#25 | |
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Quote:
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#26 |
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i own 2 Omega Speedy (a Pro and a Triple Date), 3 Tudor Tiger till now and I just found out today how to read the tachymetre bezel (never felt the need to know before), and I just thought they look cool on these watches since most of my dive watches are the normal 60 units bezel.
I get to know something new everyday. |
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#27 |
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Nice post
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#28 |
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Is it possible to have a decimal bezel installed during factory service? Mine is under warranty, and needs regulation. It will probably get a new crystal installed, so this would be the best time to do the swap.
____________________________ TT OysterQuartz SS/Black "U" Daytona TT GMT II-C DD OysterQuartz Brietling Aero Omega Speedmaster Pro |
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#29 |
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Real Name: Nick
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Great info. Thanks
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#30 |
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very cool info, appreciate this post.
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