Metric/Imperial Rulers

[G-CPTN]

In the US wood is still purchased in real inch dimensions. The problem is that the dimensions refer to the size of the original rough sawed size before the wood is finish planed. So a 2 inch by 4 inch by 8 feet long board is actually 1 1/2 inches by 3 1/2 inches by 8 feet long.

That is also the case in the UK.

[Pontius Navigator]

P4S or PAR

[Hydromet]

When buying timber, standard nominal thicknesses and widths for rough sawn timber are metric equivalents of the old (pre 1974) imperial dimensions - e.g. 25mm, 32mm, 38mm, 50mm etc and 100mm, 150mm, 200mm etcThat's understandable., as they are convenient thicknesses and machinery didn't need to be reset. However, the lengths are also approximate equivalents of whole feet dimensions, rather than metres. Not quite sure why this should be.

[Fox3WheresMyBanana]

All building codes are a combination of both calculation and experience. Almost all the experience in wooden structures is in Imperial units. It makes no sense to start throwing away that experience. The critical dimensions are 12, 16 and 24 inches for stud/joist spacings. Four feet is the first dimension which divides into all three by whole numbers. Sheets of 4x8 ft are the largest/heaviest which one man can comfortably handle at the typical thicknesses needed for building purposes, and 8 feet is convenient for room height. It therefore follows that lumber lengths should be available in 4 foot multiples. However, on their own this would cause too much wastage, so multiples of two feet are made. Thus, if one needs two 5 foot pieces, one buys a 10 foot piece and cuts it in half. When I built my last house, the total wastage was under 2%. Houses typically need no piece longer than 16 feet, and this also is convenient for the best use of felled lumber, and for handling by one man. It's getting very hard to find longer pieces, and in any case, manufactured engineered trusses built of smaller pieces are now cheaper than solid lumber for dimensions larger than 16 feet.
I am extensively rebuilding a 30 foot by 60 foot barn, for which I need 75 pieces 14 foot long, only 9 pieces 16 foot long, and nothing longer.

Meanwhile, here's an Imperial ruler


We still get a Victoria Day holiday over here!

Meanwhile, rebuilding my sister #1's place in England a couple of years ago, I found I couldn't get a 22mm plumbing fitting to work. Fortunately, behind me in the queue at the plumbers' merchant as I was returning it was a qualified plumber.
"How old's the place, mate?"
"Well, I'd guess from the old newspapers in the attic that the system was last renewed in the 1970s"
"Ah, you need a 22mm to 22mm converter"
Me and the young assistant just looked at him. He reeled off a part number and the assistant got it from the bin. It was a veeery slightly flared connector, must have been less than a mm. Apparently they screwed up the conversion from imperial to metric, then changed what "22mm" was about 3 years later to fix it. If you have a system installed in those 3 years....Anyway, the '22mm to 22mm converter' worked!

[Alisoncc]

All building codes are a combination of both calculation and experience. Almost all the experience in wooden structures is in Imperial units.

Few people are aware that since Drake's Armada days, all trees have been carefully bred to grow in imperial measurements. Hence trees are always quoted as being "x" feet high, rarely metres. In the early days of aviation, aircraft were only able to attain altitudes of one or two hundred feet, so knowledge of tree heights was of critical importance. This led to altimeters being calibrated in feet, even to this day.

It is worth noting that invariably incidents of a CFIT nature occur in regions where metrication has been imposed. In such places trees report back to Tree Central that they are "x" metres high, leading to mis-communications to aircraft being read as "x" feet, hence CFIT.

Alison

[Sisemen]

That’s all very well unless you’ve been disassembled and reconstituted under another heading.

[llondel]

I use whichever system is most convenient. If working in inches gives me easy numbers then I'll work in inches. If centimetres work better then I'll use those. I grew up with both and can switch and convert quite readily.

Who knows how big an acre actually is?

[Hydromet]

Who knows how big an acre actually is?

After years of survey work pre-1974, I can estimate it pretty well, but at first I used to do it by visualising 10 square chains (2 cricket pitches by 5 cricket pitches). I still visualise a hectare as "a bit more than two acres."

[ExSp33db1rd]

Apparently "they"screwed up the conversion from imperial to metric,

I was re-plumbing bits of a converted barn ( I didn't convert it) around that time, and I seem to recall that 1" and 22 mm. were compatible then, maybe so that one could buy 22mm and know that it would fit, but it was satisfying the change to metric, dunno, just know that I didn't seem to have any problems at the time, maybe now "they" have made stuff really 22mm, so that the "original" 22mm is no longer interchangeable ?

No idea, but maybe ? Just a thought.

My biggest problem at the moment is with car trailer towing hitches, 50 mm and 1 7/8" don't seem compatible, I have a 1 7/8th ball on my car, so have to make sure it isn't used to try to tow the larger 50 mm equipped hitch on a trailer. I've engraved 1 7/8" on the top of my car ball fitting.

NZ still gives the Met. with windspeed in Knots, cloud base in feet, and visibility in Metres and Kilometres. Recall having to carry a conversion card when operating into Moscow, clearances given in metres and our altimeters in feet of course. Balpa asked for one "standby" altimeter in metres, NO said the beancounters, you'll need a back up in case it fails, and if one does then you'll need a back up to resolve the ambiguity between the accurate one and the faulty one. We stuck with the card. I recall hearing PanAm having to go around from the threshold for some reason, and been told to carry out the standard missed approach and initially level off at 400 metres. Christ ! was the reply, we're already through 600 !

Do Svedanya

[OFSO]

Plumbing fitments in Germany (and probably Austria also) are measured in "Zoll". And what you might ask is a zoll ? Why one inch, of course. Car wheel sizes are also in Zoll. And Germans are so proud that they don't use inches....

[ian16th]

Who knows how big an acre actually is?

I became aware of it in 1982, when I bought my 1st SA house.

I bought in a suburb that had been planned in Imperial times, on a grid of quarter acre square plots.
So a block of four gardens was an acre and also a square.

It put things nicely into perspective.

Because of metrication, I used to get a rates bill for 991 m2.

[G-CPTN]

My biggest problem at the moment is with car trailer towing hitches, 50 mm and 1 7/8" don't seem compatible, I have a 1 7/8th ball on my car, so have to make sure it isn't used to try to tow the larger 50 mm equipped hitch on a trailer. I've engraved 1 7/8" on the top of my car ball fitting.

ISTR that UK towing balls were 2 inches, and when metric balls and couplings were introduced there were problems with sloppy or interference fits.
Someone introduced a flat machined on the top of one of the balls (I forget which) to give users a clue.

[1DC]

When metrication arrived in Grimsby, the big timber merchant in the town saw a dramatic fall off in business but a small time guy nearby trade boomed. The big merchant asked one of the tradesmen why he had moved to the other guy. Its metrication, we don't understand it but the little guy is selling in metric feet and we understand that. What the hell is metric feet said the big guy, Oh there is about 3 to a metre says the tradesman, we just tell him what we want in proper measurements and they give it to us in metric feet..
I remember going to Louth market the saturday after metrication and everything was in pounds and ounces, thought you had to go metric says I. Oh that will never come to Louth says the smallholder!!

[ExSp33db1rd]

Someone introduced a flat machined on the top of one of the balls (I forget which) to give users a clue.

My 1 7/8 ' ball has a flat top, which is where I've engraved the size, will probably get arrested now as I go around the car park lifting the protective covers to check others !

( well - one has to do something on a wet day in New Zealand )

[llondel]

They finally saw common sense with the metric stuff and let trade happen in whatever units the customer wanted, but just imposed a requirement to display a metric price.

I always remember that frozen peas used to come in 4lb bags and then were sold in 1.82kg bags.

The inch is now defined as exactly 2.54cm, so it's all tied back to the same standards.

[Slasher]

The speed of light is defined as 299,972,000 m/sec - tantalisingly close to a nice round 300 mill. IIRC there was talk once of redefining the metre so that the round number could be achieved. It was knocked on the head.

Oh and one's manhood has been measured in cm for some time now. Sounds much more impressive!

[ian16th]

The speed of light is defined as 299,972,000 m/sec - tantalisingly close to a nice round 300 mill. IIRC there was talk once of redefining the metre so that the round number could be achieved. It was knocked on the head.

Oh and one's manhood has been measured in cm for some time now. Sounds much more impressive!

Whenever I needed to convert frequency to wavelength, or vice versa, 300 was close enough!

When I needed to check how many zero's, I used the Light Program's 1500 metres and 200 Kc/s.

This was in the days when Hertz was just a Car Hire company.

[Fox3WheresMyBanana]

It's 299 792 458 m/s

[ian16th]

186,000 miles per second!

Give or take a cricket pitch or two.

[G-CPTN]

Has anyone measured the speed of light? - or is it just assumed from calculations?