Metric and customary measuring systems

[Ken S]

I agree. What surprised me was the thread size for the adjustable feet of the Tormek Work Station. I needed to run a tap through one of the threads to clean out some psint. To my surprise, the thread was US Coarse 5/8" x 11tpi. This was with a product made in Germany for a Swedish company. 

Ken

[Elden]

"The seven units of the metric system and their fundamental constants:

Meter — length. Distance traveled by light in a vacuum in 1/299,792,458 seconds.

Second — time. Exactly 9,192,631,770 cycles of radiation of an atom of caesium-133.

Kilogram — mass. Planck's constant divided by 6.626,070,15 × 10−34 m−2s.
Mole — amount of substance. Avogadro constant, or 6.022,140,76 ×1023 elementary entities.

Candela — luminous intensity. A light source with monochromatic radiation of frequency frequency 540 × 1012 Hz and radiant intensity of 1/683 watt per steradian.

Kelvin — temperature. Boltzmann constant, or a change in thermal energy of 1.380 649 × 10−23 joules.

Ampere — current. Equal to the flow of 1/1.602 176 634×10−19 elementary charges per second."

🤔 

[Thymen]

You completely missed the point AND you made an essential mistake.

I am sure I did not. I have it from a reputable source, the American institute that governs this. On a website is found a few weeks ago, if I can find it again I will post the link. (here it is, https://www.vox.com/science-and-health/2018/11/14/18072368/kilogram-kibble-redefine-weight-science)

Quote from this website:

In the United States, we still use imperial units: pounds and ounces. But really, all our measurements are derived from the International System of Units, or SI, which uses meters and kilograms as the fundamental units of length and mass.

When it comes to mass in the US, everything traces back to these puck-shaped cylinders, which are precisely machined to weigh 1 kilogram. Officially, in the US, 1 pound is defined as 0.45359237 kilograms. A foot is defined as 0.3048 meters.

End of quote

If you read my post well, you will see that I mean that in the US the weights and measures are calibrated to those we use in Europe, like the IPK. Then they use conversion factors to 'translate' these to US customary units. 

Examples of conversion factors?

- 1 kg (metric) equals 2.2046226218 lbs (US Customary)
- 25.4 mm (metric) equals 1 inch (US Customary)

And, by the way, no need to shout..... I am not blind....

[Ken S]

Gentlemen,

I started this topic to share what I found to be an interesting video. I did not mean to awaken heated measuring system passions.

Ken

[Twisted Trees]

Gentlemen,

I started this topic to share what I found to be an interesting video. I did not mean to awaken heated measuring system passions.

Ken

Measuring system discussions always get heavy, and lead to lengthy discussions 

[Ken S]

Point/pun well taken. .....

Ken

[John_B]

I will add "Do not discuss measurement conventions at the holiday dinner table" to our list.

1. No politics
2. No discussion of your preferred measurement convention.
3. No criticizing others children.
4. No sports team discussions.

[Dutchman]

Finally, I will give the solution myself, although I do not guarantee that it contains no errors.

In SI-units:
1 joule of energy
= 1 newton of force acting over 1 meter of distance
= 1 coulomb of charge passing through 1 volt of potential
= 1 watt of power applied for 1 second of time
= 1 pascal of pressure on an area of 1 m² applied through 1 meter of distance.

In US customary units:
1 foot-pound-force of energy
= 0.3333 lbf of force over 1 yard of distance
= 1.3558 coulomb of charge passing through 1 volt of potential
= 0.00181816 of mechanical horsepower applied for 1 second of time
= 144 psi (lbf per square inch) of pressure on an area of 1 foot² through 1 foot of distance

I hope that the example makes the problem clear. Who knows these conversion-factors?
And, oh YES, the US customary units have now been calibrated to the metric units.
However, the non-metric system remains old-fashioned, sensitive for mistakes and a disaster for students.

Corrections on 20190226, which confirms that mistakes are easy to make 
• In the "pressure line" the area was not defined on which the pressure acted. Both lines modified.
• US-example of pressure changed to other units
• value of "lbf of force over 1 inch of distance" corrected
• ... etc.
A long series of corrections of corrections etc. have convinced me that these units are too weird to comprehend.

[Twisted Trees]

I am 99.12345698765324077543860858653598% sure the Dutchman has it right... nearly! Thankfully I work with wood, which when you aim for that sort of accuracy, is generally a different size on Tuesdays! So am usually OK with the difference.

Except in AF v M hex keys, and cross head screwdrivers of which 2 of the incompatible types Phillips and Posidrive were standards set by the same company just to ensure that there would be lots of torn up screw heads and drivers in the world 

[Thymen]

Sorry, with 'weight' I actually mean 'mass'.

I am an engineer by profession, and do calculations whose results need to be expressed in the units preferred by the client. For most of my calculations I use a mathematical program called 'MathCad', and that programs allows you to do just that very easily.

There is a free version available at https://www.ptc.com/en/products/mathcad-express-free-download.

Oh, not to forget: on a ship I was sailing once, the (UK) cook, after having consumed almost 24 fluid ounces of whiskey, was very very sure that inches were more accurate then millimeters, and that SI units would therefor never win.

24 fluid ounces, by the way, is 24 /128 gallon, or approximately 0.7 liter, or 1 bottle, pick whatever unit you prefer...

[Twisted Trees]

24 fluid ounces, by the way, is 24 /128 gallon, or approximately 0.7 liter, or 1 bottle, pick whatever unit you prefer...

US or UK gallon 

[Ken S]

How strange that the home of Super Sized Junk Food uses a smaller gallon.   

Ken