An Experiment in Oil Migration on Metal Surfaces

I've often read that oil can spread around inside a watch and that proper watch oils are designed to "stay in place". I was a little skeptical that oil could move around all by itself until I tried an experiment involving a comparison between Moebius 9010 (a Swiss oil designed for general use in wristwatches) and "Mobil 1" 5W-30 (an automotive engine oil). Here are the results:

The areas of interest are indicated by purple arrows. At left, a test to see if an excessively-oiled metal-to-metal bearing would leak oil out onto the surface surrounding the bearing hole. At right, a test to see if drops of oil deposited onto a metal surface would migrate (move or spread). The barrel at right was mounted vertically to show any effect due to gravity.

This is a shot of the comparative test set-up after 36 hrs. The Moebius oil drop at right has stayed in place with a very slight spread delineated by the purple lines. The Mobil oil at left shows some unexpected behavior. The main part of the oil drop has sagged downward due to gravity, a lower surface tension, and a somewhat larger initial drop size than that of the Moebius oil. However, a thin film has formed and continued to grow, apparently following the circular machining marks on the metal surface. It appears that gravity has aided the migration of the lower part of the film. There remains a line of demarcation between the film and the edge of the original drop.

This is an external shot, after 17 hours, of the barrel arbor bearing hole, the inside of which was oiled excessively with the Mobil 1 automotive oil. The purpose of this test was to see if any oil is able to exit by overcoming the capillary force induced by the bearing clearance gap. It is seen that no spreading has occurred so far, although the oil "ring" itself is clearly visible. The small blob of Mobil 1 at left was added later to test spreading of a drop on a horizontal, smoother surface.

I have drawn no firm conclusions yet and am still in research mode. Therefore, conclusions will be published later as additions to this post.

Best regards,

xpatUSA

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,

xpatUSA