A glimmer of hope

[Frank S]

Back in the day while working on Cat equipment it was pretty easy to tell which system a particular machine was built under by simply checking the serial number if it was an older machine made domestically it was imperial everything made off shore it could have been a mix if it contained domestic components later machines became more metrically .leaning until virtually everything became metric. However it was not uncommon to find fasteners clearly marked in metric grades but with US imperial threads and diameters replacement bolts usually wound up being Imperial grade 8 since the only way to buy them from cat was by serial number of the machine. Now all late model cat equipment is full on metric but there are still and probably always will be many propitiatory fasteners seals o rings and other parts which will never be true to either system but a combination of both just so you have to buy your replacements from cat

[Toolmaker51]

Back in the day...fasteners seals o rings and other parts which will never be true to either system but a combination of both just so you have to buy your replacements from cat

Yes, most assuredly. It screens out certain wannabe mechanics; to capture a lyrical phrase "...cant' find what I'm lookin' for".

Only for some folks...We know how to measure, read a catalog and order! Anyone else have a McMaster-Carr sized set of web bookmarks?

[Frank S]

Yes, most assuredly. It screens out certain wannabe mechanics; to capture a lyrical phrase "...cant' find what I'm lookin' for".

Only for some folks...We know how to measure, read a catalog and order! Anyone else have a McMaster-Carr sized set of web bookmarks?

Maybe not that large yet. my bookmarks runs 5 folders deep my other bookmarks folder has so many pages and folders in it that it is easier to just type in what I am looking for in the browser and hope to not have to sift through 1000's of erroneous do nothing mean nothing unrelated web pages
It's my C drive where I find most of what I need, since I have nearly as many folders running sometimes 10 sub folders deep, as Microsoft has line codes for their OS

[mklotz]

The nautical mile (6076.12 ft) is a good example of a useful occupation-specific unit. Because it was originally made equal to the length of an arcminute of latitude, a navigator could easily read distances off his charts marked with latiude and longitude. However, since the earth is an oblate spheroid, the length of an arcminute of latitude is not constant so the unit value was indeterminate. Given the utility of the unit though, it was incorporated into the SI system and is now defined as exactly 1852 meters. The unit of maritime speed, the knot, is also included in SI and is set at one nm/h (1852 m/h).

The trick with such useful derived units is not to let them loose in the world at large. Use of the nautical mile is largely confined to the areas of nautical and aeronautical navigation. Nobody is putting up road signs showing distances in nm, nor are drapers selling cloth by the milli-nm.

Chalking the number of times a sheet of steel has been through the rollers is probably useful in a rolling mill. But once you start selling sheet steel forget those chalked numbers and list it by thickness using the commonly accepted measurement system (which means metric most everywhere).

[NortonDommi]

Early on the Americans also used Whitworth but soon realized that the 47 degree thread angle was not as strong as a 60 degree

Actually Whitworth has a 55 degree included angle.It should be noted that Joseph Whitworth designed his thread at this angle for several reasons, the most obvious is the materials in use at the time, mostly cast iron of one sort or the other and the head sizes were made at the ,(large to us today),sizes so as to distribute the load, the thread also has rounded peaks and roots for strength, Whitworth is actually a very good thread form. If you do some homework you will find that the ISO metrickery size threads are very closely related to Whitworth. As for common metrickery sizes those damn French who came up with it use 7,11,15 and other weird sizes,(probably a 13 in there too), and yes you do need 16,18,20mm size spanners and sockets to work on their stuff. They also label their engines backwards so there is no hope for them.
As someone from the civilised side of the ditch I would love to hear more about this new sizing system in Australia, perhaps some French consultants were brought in to advise?

[NortonDommi]

A lot of mechanics, engineers of all kinds have these really neat steel rules with a sliding pocket clip on them that doubles as a measurement stop. Quality micrometers if Imperial ones usually have decimals and their fraction equivalents etched in the frame, some verniers,(nearly spelt verynears), have the same on the back of the vernier frame.
If you wish to know more about ancient measurement systems and what they were based on and why the Egyptians had common and Royal Cubits have a look here:
Ancient Celtic New Zealand
There is over twenty years worth of research that NOBODY has yet managed to refute.

[MiTasol]

A lot of mechanics, engineers of all kinds have these really neat steel rules with a sliding pocket clip on them that doubles as a measurement stop. Quality micrometers if Imperial ones usually have decimals and their fraction equivalents etched in the frame, some verniers,(nearly spelt verynears), have the same on the back of the vernier frame.

And everyone whose profession involves aviation level quality control knows that every time you do a conversion on a measurement you introduce a potential error. Gimli glider and Mars Climate Orbiter being classic examples of the results of this. see http://www.homemadetools.net/forum/e...rbiter-61787-3

Reading the dimension as .0001 inches or .001mm then converting to 128ths to find you are 1/256th out and converting that back to thous before making your next cut is introducing multiple fail points.

I suspect that you still calculate your cars "fuel consumption" in Miles per Gallon rather than litres per 100km because that is the way your great grandfather did it.

L/Km involves dividing the Km your odometer says you traveled by the quantity of fuel added. One simple calculation, minimal chance of errors.

MPG involves converting the km on your odometer to miles, first chance of failure, then converting litres to gallons, another chance of failure, and then the third calculation to get not your fuel consumption but distance traveled for a set volume of fuel. Then when you have to work out how much fuel you need to travel 625km you need to do a far more complex calculation than just multiplying the fuel consumption by 6.25.

There is an old saying in aviation about the three ways to do a job - the right way, the wrong way and the British way because the British have a single design law - why make it easy when with a little bit of thought you can make it bloody near impossible.

[Toolmaker51]

A lot of mechanics, engineers of all kinds have these really neat steel rules with a sliding pocket clip on them that doubles as a measurement stop. Quality micrometers if Imperial ones usually have decimals and their fraction equivalents etched in the frame, some verniers,(nearly spelt verynears), have the same on the back of the vernier frame.
If you wish to know more about ancient measurement systems and what they were based on and why the Egyptians had common and Royal Cubits have a look here:
Ancient Celtic New Zealand
There is over twenty years worth of research that NOBODY has yet managed to refute.

For whatever reason, I land on this thread repeatedly. It is more than enjoyable; because sophistication of measure required in various work. Just as the different contributors. Its best to be aware and practice measurements in accord with project at hand. And NortonDommi's bit of wordplay (nearly spelt verynears) tickles my humor-sense every time.
Over the years, a set of conditions makes my vernier collection pretty damn extensive. Ranging from a treasured 6" to a near unwieldy 60"; meaning some are marked dual, most imperial.
The attraction?
1, all have adjustable calibration, and all but one have fine adjustment screws for the moving leg, same as a proper height gauge. Also benefit from sturdy flat and radiused anvils compared to short beveled type. A bearing ball easily tells the legs are in parallel. |O|
2, Digital instruments are commonly not so equipped, and verification [by other means] is problematic increasing with distance.
3, A vernier is practically self verifying, including less bulk and width than equivalent micrometer.
4, Known thickness shim stock detects contact, not so easily felt when those 60"s are used.
5, 1-2-3 or 4-5-6 blocks are nice perches on which to insure a fairly decent plane to surface plate to reduce sine errors, since few [any?] calipers sit flat.
6, With calculator at hand, who cares imperial or metric created the original, replacement must fit.

[NortonDommi]

It;s Winter her so what system should I measure the temperature in? Celsius, Fahrenheit, Kelvin or Rankine?

[Frank S]

It;s Winter her so what system should I measure the temperature in? Celsius, Fahrenheit, Kelvin or Rankine?

None of them take into account that the temperature you feel against you bare skin without having to calculate and factor in Barometric pressure wind velocity and relative humidly adjusted for altitude now when they come up[ with a gadget I can hang on the wall and instantly read the actual feels like temp everything already factored in they can name it what ever they want because that will be the name I'll use to tell my wife what she may want to wear

A few years back I was in a place where it was negative 40° my wife asked me is that Celsius or Fahrenheit because I'm always telling here it is one or the other without explaining which
I told her is doesn't matter both scales are equall at this point and both agree its **** cold