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Thread: Stupid Imperial Measure Question
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10th November 2018, 03:25 PM #1
Stupid Imperial Measure Question
I listen to FineWoodworking shop talk live and the talk imperial the one thing they say repeatedly that a board is 16 quarter or 12 quarter or 4 quarter wide - what the heck are they talking about?
Are they saying 16 times 1/4”?
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10th November 2018, 03:52 PM #2SENIOR MEMBER
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A quarter refers to a quarter of an inch. 16 quarters makes it 4 inches thick.
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10th November 2018, 03:57 PM #3
That’s what I thought.
Then why not just say 4” instead of having to going the long way about by performing a calculation 16 x 1/4” = 4”? When their seems to be no real need.
I say 147 quarters Or 36.75“
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10th November 2018, 04:10 PM #4
Another anachronism from the petulant states of Amerika.
According to Wikipedia 4/4 gives you only 7/8" of Surfaced 1 side (S1) hardwood, or 13/16" Surfaced 2 sides (S2S), as it's a nominal measurement not based on any reality that I can understand.
Good luck trying to understand the perpetual ripoff of nominal sizing versus real measurements.Pat
Work is a necessary evil to be avoided. Mark Twain
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10th November 2018, 04:59 PM #5
the way it is written is 16/4, meaning 16 quarters.
I'm not sure why the yanks use that measurement -- it might have something to do with measuring timber in board feet where a 5/4 board contains 25% more board feet than a 4/4 (= 1 inch) board.
BTW, 4/4, 5/4, 6/4, 8/4 and 12/4 are all pretty common timber thicknesses.regards from Alberta, Canada
ian
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10th November 2018, 05:57 PM #6
The above has only been more confusing. That it’s a shorthand for nominal sizes seems to make the most sense. But still I cannot imagine 8/4 board, is that a 2” x 2” board or is it just 4” thick. I think that anyone who believes that imperial is a better unit of measurement then our good old friend mm is clearly delusional.
Just out of interest the USA has legally been metric since the 1970’s. The government passed the law but never enforced it. Also when you bid for a USA government contract the speciations are metric. Also virtually all products made for the USA market are made overseas in factories building said products in metric yet they are sold in the USA in imperial measurements. So the general USA population plod along.
On a side note metric is older then imperial. The idea of a base 10 unit measure dates way way back.
Funny how history turns.
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10th November 2018, 06:38 PM #7SENIOR MEMBER
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The quarter measurement only applies to the thickness of rough sawn boards. So 4 quarter is 1 inch rough sawn, 8 quarter is 2 inch rough sawn, 6 quarter is 1.5 inch, etc. This measurement is different from 'dimensional' or framing timber which would be known as 4x2 or 2x2, and so on. With dimensional lumber, yes you will not get a full 4inch by 2inch board for example. But with rough sawn, a 4 quarter rough sawn board will be 1 inch or even slightly over. The fact that the dimensions reduce once surfaced is a different story - the quarter measurement makes no guarantees on what the S4S dimensions will be. It's not as if rough sawn boards here in Australia are measured any differently, a 25mm rough sawn board is only guaranteed to be 25mm in thickness in it's rough sawn state. But we can make an educated guess that in most cases we can at worst get a usable 19mm board out of 25mm rough sawn.
My guess as to why the quarter system is used is because the imperial system loves fractions. So rather than saying 1 and a half inches, it's easier to say 6 quarter. And they wouldn't use 1.5 inches because apparently decimals are the work of the devil and his ilk.
The quarter system also doesn't measure any other dimension, only thickness. Timber would be sold by the board foot. 1 board foot is a 1inch (4 quarter) board that is one foot wide and one foot long. The board foot is the equivalent of our cubic metre for timber sales. So if we have an 8 quarter board that is 6 inches wide and 4 feet long, that's 2"x0.5'x4'=4 board feet.
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10th November 2018, 06:47 PM #8
talking about an 8/4 board.
The abbreviation means a board that is 8 x 1/4 inchs thick -- i.e. 2 inches thick. 8/4 has nothing to do with the width of the board, which might be anywhere between 6 inches (150 mm) and 4 feet (1200 mm).
BUT
timber (lumber) in the US is sold by the board foot.
a "standard" board foot is 12" wide, 1 foot long and 1" (or 4/4) thick.
So a plank that is 12" wide, by 3 feet long by 1" thick contains 3 board feet.
If the plank were 12" wide, 3 feet long and 6/4 (=1-1/2") thick, it would contain 3 x 1-1/2 = 4.5 board feet.
Just out of interest the USA has legally been metric since the 1970’s. The government passed the law but never enforced it. Also when you bid for a USA government contract the speciations are metric. Also virtually all products made for the USA market are made overseas in factories building said products in metric yet they are sold in the USA in imperial measurements. So the general USA population plod along.
Either the people involved shouldn't have been let out of the asylum with a calculator, or it was a deliberate ploy designed to make the conversion process fail.
On a side note metric is older then imperial. The idea of a base 10 unit measure dates way way back.
Funny how history turns.
Base 12 measurement systems are much more flexible that base 10 systems.
10 can be readily divided into halves or fifths, but 12 can be evenly divided by 2, 3, 4 and 6 -- a much more flexible approach.regards from Alberta, Canada
ian
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10th November 2018, 07:10 PM #9
Metric must be inferior. Look what it did to NASA CNN - Metric mishap caused loss of NASA orbiter - September 30, 1999
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10th November 2018, 07:20 PM #10
Thanks for explaining the board foot.
Thought experiment.....
I once read why we use base 60 for time is because it’s easy to calculate and it has passed down to us from the Babylonians.
The same for angles. If a circle was made of 100 degres. Imagine calculating angles a miter it would be 25.5 degrees by 25.5. Plus it would not be as accurate. Maybe if a circle was 400 degrees then that would work.
Metric clocks exist but I doubt that we will ever go metric for time. Unless we start travelling outside our solar system. Where a 12 months and 365 days would make no sense.
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10th November 2018, 07:32 PM #11
That NASA story is famous and the lesson is what ever unit of measure you use you must use it consistently.
Imagine measuring half your project in inches and then the other half mm.
One component read units in metric and the other in imperial and the data was not converted from one to the other and it ended up in a big bomb.
I once talked to a friend about the history of the metric meter and how it has changed over time. He was convinced that it would be great to have that perfect meter.
However the more I thought about it I realised that it matters not how long a meter is as long as your definition of a meter did not change.
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10th November 2018, 07:56 PM #12
I suppose it depends whether you're talking about the US Meter or the English Metre or Meter.
The English Meter can vary greatly in size, depending on what it measures. My water meter, for example, is about a foot long, whereas a parking meter is much smaller.
I sometimes wonder how long the US Meter has been around, compared to the English Metre and Meter?
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10th November 2018, 08:26 PM #13
Look up tons their are like a dozen tons
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10th November 2018, 08:33 PM #14GOLD MEMBER
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10th November 2018, 08:37 PM #15
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