Australia is being de-metricated!

[turboplanner]

I spent a lot of time once converting 40 feet to the inch plans into 1:500. Cost our company a fortune and barely changed the plans at all.

I'm working in that right now, programming a CAD system to read data from an Excel input spreadsheet which has calculated dimensions needed for a truck to be within legal dimension and mass limits. It will be used in the US so has to read US imperial drawings with a different set of legal criteria.

 

As part of that I found that you can start with an imperial drawing and redraw in metric, just by adding a simple conversion chart into the spreadsheet which supplies the coordinates to the CAD drawing.

 

It used to take me about a week to draw a semi trailer on a drawing board; now it's possible for a drawing to be produced automatically from the calculations used for dimensions and masses.

[turboplanner]

I don't own a metric tape...I never converted...I'm dyslexic with numbers Imperial works for me metric doesn't . The bus in my avatar is 36 foot long .

Bernie .

I started forcing myself to think in metrics by holding my thumb and forefinger 50 mm apart measured by a metric only rule. After a while I could visualise 50 mm, then I could visualise 100 mm, then 10 mm then 1 mm, all using similar props to my fingers, then I learnt to visualise a metre. then, when I was aking something new around the farm I built it in metric so I didn't have to do any conversions.

 

Today I get stuck trying to remember whats a third of 15/16" or doing a conversion of 3'-3 9/64.

[skippydiesel]

Seems to me the building trade & supply have never converted - even when its in M its still mostly in the old Imp dimensions

[Old Koreelah]

I started forcing myself to think in metrics by holding my thumb and forefinger 50 mm apart...

My technique was to imagine a litre of milk as a kg, a bucket as 10 litres, two normal steps as a metre...

I built my entire shed without a tape measure, just using parts of my body as measuring sticks:

Fingernail 10mm, 100mm across my fingers, 200mm stretched hand, elbow to wrist 300, elbow to fingertips 500, arm span 2 metres, floor to belly button 1200, to nipple 1500, to eyes 1800, to wrist resting on head 2000...

 

I don't own a metric tape...I never converted...I'm dyslexic with numbers Imperial works for me metric doesn't . The bus in my avatar is 36 foot long .

Bernie .

 

Bernie I'm crap at maths, so the simplicity of metrics was a godsend for me.

 

The bit I love the most that all measurements are based on the same standard unit.

The original metre was 1/10 millionth the distance from the North Pole thru France to the equator. That makes the planet 40,000 km around.

 

A cubic metre of water is 1,000 litres and weighs a tonne. A thousandth of a litre is a millilitre (1cc) and it takes one calorie of energy to heat that much water one degree C.

The Celsius scale goes from zero at freezing of water to 100 when it boils...

[turboplanner]

Seems to me the building trade & supply have never converted - even when its in M its still mostly in the old Imp dimensions

There are millions of Australians who don't care. Walk into a house with a set square and a level and start checking; they might as well be measuring in the old corn seed system.

[Bruce Tuncks]

I reckon the building trade converted and used the conversions to pare a bit off . For example, a 4 by 2 should be 100 by 50 but what you see is 90 by 45.

With steel, I for one think of 75 to 200mm deep c section. Nobody refers to c sections in inches.

But I have to agree about tyre pressures. I too still think in psi.

And I like having a set of imperial drills... with a metric set too, you can usually find the right size.

I reckon us aviation types use the most imperial on account of the US being the main supplier of hardware.

[spacesailor]

Unless,

You have a V W engine.

What does 1/ 10 millionth ?, mean, like most French things it,s complex.

12 parts to the metric system, 6 larger than the metre 6 smaller than the metre.

spacesailor

[kgwilson]

The US was one of the first countries to convert to decimal currency and the Metric Act in 1866 supplied all of the standards to each State and they have been trying to convert ever since with a number of different Acts. The conundrum is the federal system and the conservatism of those in power who bow to those who finance them. The US is now the only industrialised country in the world not to use the metric system and along with Liberia and Myanmar are the only countries that have not officially adopted metrication as the primary means of weights and measures. The US military uses metrics but that was likely pressure from the rest of NATO.

 

I am now fully metric. Tyre pressures & my height were that last to go. My problem is with Aviation because we get most of our materials from the US so I have to have AN bolts & charts and imperial drills. Same with thread sizes. It is a nightmare, all those stupid fractions. I needed a new brake line fitting & the thread is UNF. The hydraulic shop only had BSF but that was a stroke of luck as there is only about 1 thread in 30 difference so a male BSF will fit in a female UNC but not the other way around. Crazy.

[turboplanner]

It is a nightmare, all those stupid fractions. I needed a new brake line fitting & the thread is UNF.

I still use UNF bolts for race car design in critical areas because the thread locks better and stays tight better, even with a shakeprooof washer, whereas every attempt I've made at getting a metric thread to do the same jobs results in the bolts coming loose, but that's the only exception.

[Old Koreelah]

The US was one of the first countries to convert to decimal currency and the Metric Act in 1866 supplied all of the standards to each State and they have been trying to convert ever since with a number of different Acts. The conundrum is the federal system and the conservatism of those in power who bow to those who finance them. The US is now the only industrialised country in the world not to use the metric system and along with Liberia and Myanmar are the only countries that have not officially adopted metrication as the primary means of weights and measures...

The conversion was happening gradually (glacially?), then Reagan stopped it, calling metrics "unAmerican"!

He was also the president who created their huge deficit, but little details like competence shouldn't get in the way of image...

[turboplanner]

I built my entire shed without a tape measure, just using parts of my body as measuring sticks:

Your shed is based on the biblical Cubit system then.

Many farmers do the same, and eye off the first corner post against a straight tree and the others against the fourth one.

My grandfather built shearing and hay sheds using the 3,4,5 method of achieving 90 degrees, never knowing that the Egyptians used the same method.

The Egyptians related length and width to the compass points, so incorporated the 1 in 60 component, and also proportioned the circles to fit in, but we've lost those skills now.

Alexander Thom wrote a book about the Megalithic Yard which was approximately three feet, and was duplicated in ancient sites from the south of England to the Scottish Islands.

All of these came together to make the imperial system much more elegant and related to the earth and solar system than the metric system.

[turboplanner]

The US vehicle manufacturers switched to metrics years ago; I work directly with them, and all the drawings these days are metric only with no imperial measurements other than on some subassemblies like wheel sizes, tyres and brakes where probably only a war will produce the amortisation cost factor which would allow a change.

However the peripherals, like sales people still talk imperial, so all the product literature has to be dual system, and they perpetuate the imperial freeze by talking to the customers about imperial wheelbases and horsepower because they believe that's what the customers want to hear.

In my car there is a switch, which changes all gauges to metric or imperial, whichever the driver wants.

[kgwilson]

They need to put a switch in the heads of all the Yanks. Elon Musk is designing one as we speak. The problem is it will be hijacked by the conservatives & back they will all go.

[M61A1]

My technique was to imagine a litre of milk as a kg, a bucket as 10 litres, two normal steps as a metre...

I built my entire shed without a tape measure, just using parts of my body as measuring sticks:

Fingernail 10mm, 100mm across my fingers, 200mm stretched hand, elbow to wrist 300, elbow to fingertips 500, arm span 2 metres, floor to belly button 1200, to nipple 1500, to eyes 1800, to wrist resting on head 2000...

 

 

 

Bernie I'm crap at maths, so the simplicity of metrics was a godsend for me.

 

The bit I love the most that all measurements are based on the same standard unit.

The original metre was 1/10 millionth the distance from the North Pole thru France to the equator. That makes the planet 40,000 km around.

 

A cubic metre of water is 1,000 litres and weighs a tonne. A thousandth of a litre is a millilitre (1cc) and it takes one calorie of energy to heat that much water one degree C.

The Celsius scale goes from zero at freezing of water to 100 when it boils...

It's all well and good until you add Newtons.

We have some French made stuff at work that's load rated in DecaNewtons. You have to wonder what they were thinking.

I have just learned to manage working with what I'm given.

[skippydiesel]

One of the many reasons I like my ATEC Zephyr, is that it, unlike so many aircraft, is all in M-----Soooooooo easy!

[turboplanner]

I stand to be corrected but it seems that most, if not all automotive brake systems are imperial, often with metric equivalent quoted - how come?

Cost to change

[Old Koreelah]

...All of these came together to make the imperial system much more elegant and related to the earth and solar system than the metric system.

Turbs I agree with all your post except this last bit; while there is much fascinating history to traditional measurements, they are a pain in the proverbial to use. (You forgot one: the carat, used for weight of gems and previous metals, is derived from one carab seed).

 

As I outlined in Post #29, the entire metric system is based on a measurement of the earth, and it's elegant simplicity is the interrelatedness of it all.

[Old Koreelah]

It's all well and good until you add Newtons.

We have some French made stuff at work that's load rated in DecaNewtons. You have to wonder what they were thinking.

I have just learned to manage working with what I'm given.

A Newton is defined by the metre, the kilogram and seconds, so what is the problem?

And yes I agree that the French have come up with some strange multiples. Our Peugeot's speedo shows 50, 70, 90 km/h which has caused problems at times, but it's engineering is superb.

[old man emu]

Screw Thread Terminology

Some of the common terms faced when looking into thread types and sizes are summarised below.

alt=llustration of a threaded fastener with useful terms labelled

https://i0.wp.com/staqoo.ie/blog/wp-content/uploads/2018/01/fastenerwithterms.jpg?resize=455%2C301&ssl=1[/img]

 

Figure 1: Illustration of a threaded fastener with useful terms labelled (Ispatguru.com, 2018)

 

Major Diameter – Largest fastener thread diameter. For example, in a screw the major diameter would be the diameter of the shaft.

 

Minor Diameter – Smallest fastener thread diameter. For example, in a screw the minor diameter would be diameter of the inner part of the screw with the exception of the crests of the helix.

 

Pitch – Linear distance between one thread and the other next to it.

 

Thread Length – The total length of the threaded part in the fastener.

 

Flank – The angle at which the thread crest is raised from the thread root.

 

 

I still use UNF bolts for race car design in critical areas because the thread locks better and stays tight better, even with a shakeprooof washer, whereas every attempt I've made at getting a metric thread to do the same jobs results in the bolts coming loose, but that's the only exception.

 

That is interesting when one compares the pitch of Metric and UNF. Let's take two similar diameter bolts - M6 and 1/4 UNF. The pitch of the M6 is 0.75 mm, while that of the 1/4 UNF is 28 TPI (which works out to be 0.889 - call it 0.9 - mm). Both bolts have the same Flank angle of 60 degrees, which is not relevant to this discussion.

 

Let's take the example of bolts fastening two metal plates together. The bolt itself is not doing any fastening, apart from providing a stopper at the head against which the nut is torqued. It is the nut that does the tightening. Let's look at the nut, which has the same pitch as the bolt thread. We'll make the nut 10 mm thick.

 

 

Hark! I hear the dulcet tones of SWMBO calling to me like the mournful foghorn call of an Iberian-registered tramp steamer wandering in a Dover Strait fog. I'll come back to this discussion later today - OME

[Bruce Tuncks]

A decaNewton... is that ten Newtons? if so it will be real close to a kilogram, on earth anyway.

[Bruce Tuncks]

I never got my head around slugs. Or roods.

[turboplanner]

The pitch of the M6 is 0.75 mm, while that of the 1/4 UNF is 28 TPI (which works out to be 0.889 - call it 0.9 - mm).

I see you were about to write more, but so far the UNF bolt has an 18% coarser pitch. Could just be a harmonics sweet spot.

[old man emu]

Quick note during smoko

 

It's all about friction. Tell you more later today.

[skippydiesel]

Cost to change

Yeah! but its been about 50 years since we (UK) were transitioning from Imp to M. In that time almost every manufacturing system must have been replaced/changed over multiple times.

[hihosland]

we had 7points in the rain gauge this morning.

My USA son in law works with a decimal inch tape measure ie 10 divisions to the inch.