The names were obviously chosen to be close approximations to the actual metric
sizes the records were made to. I believe it was done to satisfy the English
speaking public at a time when metric unit names were either unknown or
feared.
As you noted in the previous post that if the records were made today they
would be metric. Then I would ask how would they differ from the sizes in the
past? Would a Berliner 250 mm disk still be a 250 mm disk today? I would
agree that the 302 mm American disk would be 300 mm like everyone Else's.
Possibly the 175 mm disk would be a 200 mm today so that each record size is
only 50 mm apart. We can only speculate.
Depending on who markets the product today would determine whether imperial
names would be chosen over metric descriptive names. The floppy disk was a
modern example of a metric designed product given an imperial name.
Do you see my point?
Jerry
________________________________
From: Stephen Humphreys <barkatf...@hotmail.com>
To: U.S. Metric Association <usma@colostate.edu>
Sent: Sunday, April 5, 2009 9:29:02 PM
Subject: [USMA:44417] RE: Records
Rather than putting words in to my mouth why not quietly back off? It would
work better.
Remember that these sizes are as they are or historical reasons more than
anything else.
You should not get wound up about it. It's such an 'extreme' reaction ;-)
________________________________
Date: Sun, 5 Apr 2009 07:52:34 -0700
From: jeremiahmacgre...@rocketmail.com
Subject: [USMA:44383] RE: Records
To: usma@colostate.edu
Stephen asserts the records are true to their name (ie a 12 inch named record
is really 305 mm in diameter). But since the rounded metric sizes are the true
and original sizes, then they are metric based and only were converted to
inches for US manufacturing at the time. It is obvious from the RIAA spec that
the original metric based dimensions were still intended but that the slight
differences within tolerances occurred as they wanted them to be described in
inches in vulgar fractions.
How does one accurately express a rounded millimeter value in a vulgar inch
fraction and stick to either 8-ths, 16-ths or 32-nds? For example, if you were
an engineer in the 1920s and had to convert a European metric spec for American
use, how would you do it and still retain the same original dimensions in the
converted value?
Jerry
________________________________
From: John M. Steele <jmsteele9...@sbcglobal.net>
To: U.S. Metric Association <usma@colostate.edu>;
jeremiahmacgre...@rocketmail.com
Sent: Sunday, April 5, 2009 10:34:35 AM
Subject: Re: [USMA:44375] RE: Records
Your dimension of 302 mm is correct, more correct than the nominal 12".
However, Steve's assertion that it is inch based is also correct, as written in
the specification.
Since the International size is claimed to be 300 mm, and 302 mm differs from
it by a few multiples of the tolerance, as an engineer, I have to say they were
engineered to be different sizes, even if they are "close." Assuming the
International size has a similar tolerance, they will not overlap.
--- On Sun, 4/5/09, Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com> wrote:
From: Jeremiah MacGregor <jeremiahmacgre...@rocketmail.com>
Subject: [USMA:44375] RE: Records
To: "U.S. Metric Association" <usma@colostate.edu>
Date: Sunday, April 5, 2009, 9:59 AM
John,
Thanks for verifying what I have said. We now have proof that I am correct and
Stephen is wrong. But I highly doubt Stephen will change his position and
continue to spout error.
The RIAA spec is very interesting as it butts up against an interesting problem
in converting millimeter dimensions to fractional inches. I would say that in
1963 when the spec was made (possible from an older spec) that decimal inches
were rare and not popular and it was common to express all (or most) inches in
fractions. So, how do you convert a rounded metric number to a fractional inch
and then come up with a usable fractional size that is in either 16-ths or
32-nds? Anything smaller is not practical.
302 mm converts to 11.89 inches. The nearest fraction is 11.875 mm which is
11-7/8 inches. This however is only 301.625 mm. The reason for the
asymmetrical tolerances is to accommodate rounded numbers in both units, the
302 mm in metric and the 11-7/8 in inches. If we add the 1/32 tolerance to
301.625 mm we get 302.42 mm. The average of the two is the 302.02 mm you
noted, which for all practical purposes is the 302 mm intended. However, in
inches there is no common fraction to equate to 302.02 mm. So the closest
common fraction was chosen and the tolerance was made asymmetrical.
If the RIAA spec were ever to be updated it could simply drop the 0.02 mm extra
you noted and simply make it 302 mm +/- 0.4 mm. Would you agree?
I do find it interesting that the RIAA wanted their records to be an extra
millimeter in radius bigger then the standard 300 mm. Could be they wanted to
have extra leader space at the beginning.
As a side note I wonder if the 1963 spec was an update to an earlie spec and
how far back the spec really goes? If so, and the inches were in fact not post
1960 inches, then how would pre-1960 inches or even pre-1900 inches affect the
outcome of the conversions?
At least we now know that the dimensions are what is intended and that the
reference to shrinkage is just wishful thinking.
It just goes to show that the extremist propaganda that claims everything in
the past started out as inch based is wrong and that there are many examples
that actually started out as metric based and were later corrupted by the
English world in inches and the metric history was forgotten. It is time to
revive the truth about products that originally were metric to begin with.
Jerry
________________________________
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