Feet and inches

I'm a Sheet Metal Worker & both imperial & metric are 2nd nature to me.

Also bieng at school in the 70's helped.

I'm a Sheet Metal Worker & both imperial & metric are 2nd nature to me.

Also bieng at school in the 70's helped.

Erm.... ;-)

It’s 13point166666666 d/inch recurring, which, when mutiplied by 55point5 is 730.75d which is Three pounds and tenpence three farthings (I can’t seem to do fractions on this iPad)

Yep - agree - I did it on an Excel spreadsheet and then checked it with pen and paper like we did at school 45 or so years ago

Thank god there's no longer a need to work out how much 4' 7 1/2" of material costs at £1 19s 6d a yard.

Some have missed the point but have made the point about this calculation.

There is more than one way to do it and the differences are small but significant.

These errors are centred around ease of calculation, unit range and combining fractions and decimal. Not a real problem if a "one off" and not signifiant compared to the errors in manufacturing.

However the errors are magnified when dealing with increasing numbers of items and not just in terms of money.

Its not metric or imperial that is the problem its the "range" of the unit and how its manipulated.

Inches would be perfectly viable when building a house if all the materials were made in inches. On an estate scale "inches" don't work so we move up to feet or yards. We still need the accuracy so do we use the sub units or fractions or decimal? Those who survey, buy and install might well have their own way of doing things which leads to cost and structural problems.

A range that costs up to ten fags on costing one unit might not be significant to some, but it is if you are roofing a Cathedral.

Imagine surveying and constructing Crossrail in imperial units.

Imagine surveying and constructing Crossrail in imperial units.

I think the Eurotunnel would have been a better example given that the French end would be in metric and the Brexit end in imperial.

I think the Eurotunnel would have been a better example given that the French end would be in metric and the Brexit end in imperial.

...and only finding out at the point of breaking through!

Some engineers' rules can have the inches subdivided into tenths, fiftieths and hundredths.

Some have missed the point but have made the point about this calculation.

 

There is more than one way to do it and the differences are small but significant.

These errors are centred around ease of calculation, unit range and combining fractions and decimal. Not a real problem if a "one off" and not signifiant compared to the errors in manufacturing.

However the errors are magnified when dealing with increasing numbers of items and not just in terms of money.

 

Its not metric or imperial that is the problem its the "range" of the unit and how its manipulated.

Inches would be perfectly viable when building a house if all the materials were made in inches. On an estate scale "inches" don't work so we move up to feet or yards. We still need the accuracy so do we use the sub units or fractions or decimal? Those who survey, buy and install might well have their own way of doing things which leads to cost and structural problems.

 

A range that costs up to ten fags on costing one unit might not be significant to some, but it is if you are roofing a Cathedral.

 

Imagine surveying and constructing Crossrail in imperial units.

Those that know what they are doing have not made any errors and calculated the sum correctly.

In the past, the UK managed very well with imperial measurements and led the world in engineering.

The fact that you or others may not understand how this was done does not make imperial inaccurate or imprecise.

Those that know what they are doing have not made any errors and calculated the sum correctly.

In the past, the UK managed very well with imperial measurements and led the world in engineering.

 

The fact that you or others may not understand how this was done does not make imperial inaccurate or imprecise.

Quite right there, the accuracy of something is not really determined by what units it is measured in, a precision part can be measured accurately using imperial or metric, most modern digital metrology equipment will switch between them both at the push of a button.

---------- Post added 18-12-2017 at 20:07 ----------

Some engineers' rules can have the inches subdivided into tenths, fiftieths and hundredths.

Most engineers rules have a combination of metric and imperial, and not to forget the subdivisions of halves, quarters, eighths, sixteenths, thirty-second's and sixty-fourth's.

Quite right there, the accuracy of something is not really determined by what units it is measured in, a precision part can be measured accurately using imperial or metric, most modern digital metrology equipment will switch between them both at the push of a button.

 

---------- Post added 18-12-2017 at 20:07 ----------

 

 

Most engineers rules have a combination of metric and imperial, and not to forget the subdivisions of halves, quarters, eighths, sixteenths, thirty-second's and sixty-fourth's.

Straight away we have a problem when some use fractions based on /10 or /000 and some use 1/2, 1/4, 1/8, 1/16 , 1/32, 1/64 etc. Fractions are often more accurate than decimal, but can be harder to work with

The history of engineering is littered with errors, mistakes, misunderstandings, confusion, lack of QC etc. which have led to delays, cost overruns and accidents. We have successfully learnt from these mistakes and adapted safe-guards including standardization of method and practice which includes reducing the number of units and using some as a base.

Steam engines blew up not because of imperial units but because the hand was on its second time around the pressure gauge- We've come a long way since Brunel's failures.

Those that know what they are doing have not made any errors and calculated the sum correctly.

In the past, the UK managed very well with imperial measurements and led the world in engineering.

 

The fact that you or others may not understand how this was done does not make imperial inaccurate or imprecise.

The issue with imperial units isn't their precision, it is how easy it is to convert to different scales and dimensions.

To convert between metric distance units you just move the decimal point. To convert between successive imperial distance units you have to to multiply/divide by 12 or 3 or 1760 - or various other numbers depending on exactly which units you are converting from and to.

A litre is 10cm x 10cm x 10cm so figuring the dimensions of the space required to contain a given number of litres is straightforward. With imperial units there is no intuitive way to think of how much space a given number of pints will take up. A 1m cube is 1000 litres, how many pints is a 1 yard cube?

1345 and a bit.

I'd get out my conversion tables to find what that bit is, if I needed.