# Ultimate digital caliper for modelers.

• posted

I just prefer the SI-system, as I do not have to remember all those conversion factors. Or would you prefer to use roman numerals for calculations :-)?

Marc

• posted

Well, having been brought up with both, and having bought all kinds of things measured in both systems, and having lived through an incomplete conversion to metric here in Canada, my considered conclusion is that the old system is more consumer friendly. Why? Precisely because its measures are based on the human body.

And human drinking capacity. Have you noticed that "standard" metric drinks are sized very close to the old measures, with some rounding off here and there? Eg, a half pint is 227ml - the standard soft drink in Europe is now 250ml, which is about one tablespoon more.

There's also the convenience of estimating quantities that give us results within a half unit or so. For a carpet, for example, a centimetre is too small, and a metre too large, but a foot is just about right.

The usual argument in favour of the metric system is that it's "rational", because all its units are related to each other by powers of

10.*** Well, so what? The hard fact is that most people never convert units into each other -- they never need to do so. People need units that are easy to imagine in terms of use or consumption. It's no accident that in Austria when I were a lad sliced meat was bought by the "Deka", ie the 10gm unit. It's rather small, being less than half an ounce, but it's in the right range - a slice of ham weighed about a Deka, depending how the butcher set the slicing machine. On a recent trip to Austria I shopped at a farmer's market. I noticed that people asked for "about 1/8 kilo" of cheese, etc, not for 125gm. Interesting, eh?

I have nothing against the metric system, I use it a lot, actually. But I do get testy with people who believe that it's inherently superior to other systems of measurement. It isn't. It's just different. The same goes for the imperial system. Use either for what it's good for, and ignore it otherwise.

HTH

• posted

"Marc Heusser" wrote in message news: snipped-for-privacy@news.unizh.ch...

That's JUST my point. Were I facile in the use of roman numerals, it would (probably) be just as natural and easy for me to use it that way as it is for any other measurement system with which I was fully competent. It really doesn't matter, so long as it's 'standardized' and well-documented.

LLoyd

• posted

My old physics professor said: "There are two mensuration systems: the metric and the barbaric."

But to get back to the topic that started this amazingly long thread. Us modelers use a large variety of sources for our models: kits, plans, sometimes very old documentation (that may use the stone-furlong-fortnight mensuration system.). Kits and plans come in an amazing variety of scales:

1:4, 1:5, 1:6, 1:8, 1:12, 1:16, 1:24, 1:25, 1:32, 1:35, 1:48, 1:50, 1:75, 1:96, 1:100, ...1:720 ..and probably a whole bunch more that I've missed. The base may be either in feet and inches, or metric. Our materials, today, are usually either metric or English or both. So, let's say I have some small brass strips sized in inches, and I'm building a 1:75 scale model with metric plans. I want to know in an instant if that strip is the size I want...without dragging out a calculator, without having an RS-232 or other cable winding itself like a cobra around my delicate model, without a blue-tooth transmitter dragging my wrist down, and without having to go to the other room to look at the computer screen because my shop is not a healthy place for computers. I want to do that conversion in an instant. Apply my caliper to the material and instantly read the scale dimension in the proper units. The ultimate digital caliper for modelers would do just that.

Boris

• posted

I don't think the basis for the system is the point. That is obviously going to be arbitrary. It's the conversion process that makes the American system ludicrous. 12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile. Great if you have a calculator or an autistic savant handy.

With metrics the conversions are all based on factors of ten. Makes it really easy, even for children with very little knowledge of arithmetic.

Working just in your head, figure the number of centimeters in 8346 kilometers. Now try figuring out how many inches there are in 8346 miles as quickly. It's like doing long division with Roman numerals.

• posted

When you get into thermal conductivity units and that sort of thing, mixed Imperial units can get pretty ugly. BTU*in/(ft^2*h*°F)?

Best regards, Spehro Pefhany

• posted

Spender wrote: [...]

Yeah, except that one doesn't do conversions very often. I mean, I doubt that you convert miles to yards when you're driving across town to the hamburgre joint.

Or do you?

H'm.

Yeah, well, sure, but why on earth would you want to _do_ that?

• posted

My grumbles at the imperial length system come from three factors;

- very strange numbers of each division in the next one up. eg 5280 feet per mile, 66 feet per chain etc.

- nearly unworkable fractions of each inch, plus thou's.

- assorteg "gauges" of wire, screws and the like which differ between countries.

Regards, Greg.P.

• posted

Scale modelling would be almost impossible using roman numeral fractions!

Imagine converting a XXXI' IX +VIII/XII" long wagon/car to XXIII/M scale! Just converting the result to barleycorns would take a day's calculations.

Regards, Greg.P.

• posted

You do conversions whenever the need arises. For anyone who needs to do conversions a lot, the American system is a major hassle. That is why most American scientists and engineers use the metric system.

The American public is just too dense to change. That's okay for the older generation, but they should mandate the metric system in schools so the next generation doesn't keep looking like a bunch of hicks to the rest of the world.

It's just an example.

• posted

Greg Procter wrote: [...]

Standards are a whole 'nother can of wigglies. At least we now have the ISO, which is sl-o-o-o-owly bringing some order into the mess. But please note that the measurement system used to specify the standard is irrelevant, so long as the standard is accepted by everyone. Look at containers - specified in feet, not metres, and for a very good reason: they have to fit on US RR cars... :-)

I was an engineering student for two years, and found that besides the slipstick, the most important tool was the conversion factors booklet given by The Dominion Steel and Coal Corporation of Canada to all us impecunious seekers after technical wisdom. I still have that booklet - I still have two slipsticks, in fact -- and it's a goldmine of useless information. :-)

Here's a few conversions that the decimal system supposedly simplifies:

1 km/h == 0.2778 m/sec 1 KWh == 3.671x10^5 kg-m 1 mm mercury == 0.001315 atmosphere == 13.595 km/m^2

And so it goes. Many of the more important conversions are not simply movements of the decimal point, because Nature isn't decimal.

IOW, the metric system is really a decimal system, and any group of base unit whatsoever would have served - so why is the meter what it is? Because the French Republic decided that a "natural" measure of length would be 1/10,000 of the quarter circumference of the Earth, as measured along the meridian passing through Paris. Unfortunately, the guy who was given the job of surveying that line made a few minor errors, so that the metre is pout by about 1 part in -- wait for it -- 10,000....

Hah!

Footnote: they're called "gauges" of wire (and sheet metal, etc) because it's easier to measure those things with gauges than with calipers. Which brings us back where we started from.

Hoohah!

It's been an entertaining ride. Thanks, guys!

HTH

• posted

Errr, the ISO container standard was based on a British design, so for that reason the original dimensions were Imperial. The ISO quotes the standards in bothe feet/inches and millimeters.

Problem #1 is which of my selection of gauges should I use to decide which wire or screw to use or purchase.

A real life example: I want to mount my newly built wagon (flatcar) on proprietry bogies (trucks) The bogies have a kingpin hole of 6mm diameter. I need a styrene plastic tube kingpin of 6mm diameter and a screw to thread into said tube. Find the tube comes in inch fraction increments externally and internally. I can figure 1/4" = 6.35mm (unless of course it's 6mm tube labelled

1/4") The internal diameter isn't stated, but one can infer that it nearly matches tube two sizes down. Add tube two sizes down to shopping list to get sufficient wall thickness - internal diameter will equal tube outer diameter two sizes down. The screws in the hardware shop come in gauges, whose particular gauges unstated. Screws and taps at home all metric sizes. Attempt to convert 1/4" - 4/32" to metric in head, add thread depth (opps, two thread depths) and the visualize that in terms of unknown screws in semi-clear containers in hardware shop. Go home - create king-pins and rat small tin of random size PK screws for "something suitable". ;-)

Regards, Greg.P.

• posted

Greg Procter wrote: [...]

Interesting. A nice example of why one needs standards, so that one doesn't have to do all this furshlugginer converting back and forth. I use NMRA standard trucks: they all come with kingpin holes that take a #2 (American) screw of bolt. Piece of cake. I just don't buy trucks that don't conform to NMRA standards. Since after-market replacement trucks are bought by "serious" modellers (like me??? ROTFL), the manufacturers make sure their trucks conform.

Ah well, there's always a work-around. :-)

HTH&HF

• posted

Hmmm, there isn't any NMRA standard for 'NZR G24 scale', I make it up as I go along. How should I know if screws in the hardware shop are US #2 or Brritishish #2 gauge?

• posted

How does 1/4" factor in?

Cheers, John

• posted

The only suitable sized styrene plastic tube my hobby shop stocks to make a kingpin is in fractional inch measurements. (Evergreen) The LGB and Bachmann bogies have a loose 6mm pivot hole. Styrene because I need to make a rigid mounting point within the frame depth of a flat deck wagon. Using a quarter inch screw into the styrene frame as a kingpin would leave too few threads holding for the forces likely to be encountered. My lathe was and is still packed away due to a major move so the engineering was under kitchen table standards. (actually, the kitchen table was also packed)

• posted

The gages don't count, as they were not standardised, except in the particular trades that originated them.

In their context all the units of the imperial system have their place. Feet and inches are logical and usefully divided units for the things they generally get used for, as are rods, chains, and miles.

Arguing that they are not usefull, on the basis that they do not easilly convert to other less practical units for the purpose, is a mugs game, to be played by those that wish to make excuses.

So it's tough to translate rods to inches. So what!

I find it somewhat funny, that the school system in Canada is teaching imperial measures again, as someone figured out the reality, that a great deal of the world has been divy'd up into 1 mile by 2 mile squares, (take a look at the Canadian prairies on a sattelite view, eg: Google Earth), and that a guy who is expected to be able to go into a pre metric building and do repairs, renovations, or the like, must be conversant in the units that the building was built with, both lumber and hardware, if he wishes to come out with any numbers that make sense.

Cheers Trevor Jones

• posted

If you order a wee dram or a gill of whisky in Scotland, you will be served correct measure.

Other curious discrepancies: "caliber" is generally understood to mean diameter of a bullet in hundredths of an inch, as .30 cal is about .30 inches dia which happens to be 7.62 mm. (Fancy that!) OK, but ".380" is really 9mm Kurz (short) which is .3543" dia. Further, ".38 special" ammo is routinely used for practice in ".357" handguns.

• posted

That's because of our American neighbours who dominate much of our lifestyle. Ironically, their metric conversions are more accurate than what we use.

Cheers, John

• posted

Good Morning to you to, John,

It's got less to do with the Americans, than it has to do with several hundred years of using the same measuring system that they started out with, mainly originating in Britain.

In the mid to late 1800's the American watch industry (THE high tech industry of it's day, making interchangeable parts before anyone else in the world!) was working almost entirely in metric measurements. It had far less to do with the workmen originating in Europe, than it had to do with the appropriateness of the measuring unit for the job it was being applied to.

Legacy measureing systems are a fact of life. If you want to order a part and have it fit, you will have better luck if you order it to the same measuring standard that the item was built using. A fine example of that is the French ligne, used as a unit to measure watch movements and crystal sizes. They sorta but don't exactly coincide with the two decimal place metric measurements that are usually also printed on them.

If you want Irony, the American inch is officially defined as being a unit 25.4 millimeters exactly (changed a while back to make it an even tenth of a MM)

Cheers Trevor Jones

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