That state of metric conversion in the US

[Syd Rumpo]

Oh, I forgot the best one: we are still donating blood by the pint.

Strangely, in the UK we give a US pint of blood instead of the larger
imperial measure.

Cheers

 

[Syd Rumpo]

That's so you could go for a beer afterwards and come out ahead.

Cheers

Phil Hobbs

Yeah, part of the mantra here after donation is not to drink that day. I
just smile and nod. They do too.


Cheers

 

[Joerg]

On Sat, 16 Feb 2013 08:58:41 -0700, Jim Thompson

rickman wrote:
[snip]
Heck, I
worked at a company just a few years ago that made push to talk radios
for the US military. I was surprised that the mechanical engineers were
still using inches and converting all the metric stuff rather than doing
it all in metric!

Surprised? Some of my work is in aerospace. There it's all inches,
pounds, PSI, slugs, knots, feet and so on. To some extent that is even
so in the medical device industry. The topper:

[snip]

You forgot "Jerk"... the derivative of acceleration... used in
elevator specifications >:-}

...Jim Thompson
That reminds me of the day i saw dA-dt on a licence plate.

Maybe I should get this vanity plate: *PHUT*

No asterisks. Maybe you could get "PHUTTER". ;-)

In California you can get asterisks. Even heart shapes AFAIK. It's crazy
out here.

 

[Joerg]

Do those sizes take into account the inevitable dimensional changes that
result from any mention of catheters?

Not sure what you mean but I mostly deal with the ones used by
cardiologists. Folks on the table are usually fairly quiet when that's done.

 

[T]

The speed of light is about 1.8E12 furlongs per fortnight .

{shudder} I do like the metric version better 3x10E8.

 

[rickman]

I still have old stuff that SAE wrenches are good for, but everything
on cars seems to be metric these days with few exceptions. Some
dimensions in that Chevy are obviously hard metric (the bore and
stroke size of the smaller engine is 96/92mm). The larger engine is
mixed.. metric stroke and 4" bore.

It's a hassle to design solely in mm when tool and material sources
are largely from the US or made for US customers. More digits to enter
when machining* because Imperial tools are more available and cheaper,
less availability and sometimes higher cost of things like reamers,
etc. I don't mind 6-32 screws, for example, provided they make them
for me with Phillips heads (or Robertson or Torx). Flat blade
fasteners- ugh. The coarser thread compared to metric standard zips in
faster with the electric screwdriver.

I wouldn't mind at all going 100% metric. Even if I work in metric,
that is easier to incorporate Imperial units (is the inch really
considered "Imperial"?) since the conversion is well defined. If I were
working in inches and needed to use metric items the conversion doesn't
work out so nicely, dividing by 2.54 is a lot uglier than multiplying.

Do any Euro socket sets use mm drives? All my tools use 1/4, 3/8, and
1/2" drives. It would be a total PITA if there were 6mm/10mm/12mm
drive sets (assuming they exist) in the same work area.

Do you think a 6 mm square head isn't going to work ok with a 6.35 mm
square socket hole? I don't think the 0.35 mm difference (if it is that
much) will even affect the detent. Am I wrong about this? I expect a
square connection would be much more forgiving of size mismatch than a
12 point socket on a hex nut.

* For example, the standard edge finder I can buy easily/cheaply has a
0.2" diameter, so the offset is 0.1" from the edge of the work. (also
0.5" diamter). I can get metric end mills, but 0.25" diameter is
cheaper than 6mm. I can set the DRO to metric, but I'll have to offset
it by 2.54mm to get the edge, and 3.175mm to offset the tool radius.
vs. 0.1" and 0.125".

Sounds like a good reason to just give in and spend the extra few bucks
to get the metric stuff. I wonder how the rest of the world manages?
It much be a PITA knowing they are paying too much for their tools.

There are plenty of times when I get tired of trying to do the math on
feet, inches and binary fractions of an inch. Where do I mark cuts on a
board 3 ft, 3 3/8 inches long to space out three notches 1 5/16 wide so
the un-notched areas are all the same width? With all round metric
values I can do that in my head. 33 1/3 mm notches and 225 mm
un-notched areas.

I remember conversion cards to go between decimal and fractional inches.
I've never seen anything like that for metric. Living in the metric
world is the best way to go, living in both worlds is the worst way to go.

 

[rickman]

You're an idiot... quite old... Probably all your life.

More likely a 14mm.

So, you are too stupid to know (obviously)that some of the values match
up closely enough to substitute for each other.

US vehicles are metric. That includes General Motors Corporation, you
fucking idiot.

Isn't that a bit of a harsh reply? If they guy tried a 14 mm socket and
it was too small, that would be pretty convincing proof that the nut was
9/16 inch and not metric. I don't automatically assume someone like
Joerg is an idiot.

I find it more likely that some device might have been in use long
enough that it had not been converted to metric yet. But then I haven't
examined every nut and bolt used in building cars. Have you?

 

[rickman]

On 2/17/2013 10:21 AM, Lord Valve wrote:
....snip...

"I'm not an asshole, but I *play* one on the Internet." - Lord Valve

....snip...

And very convincingly I might add!

 

[rickman]

It is not very far from pounds and guineas (20 and 21 shillings).

My understanding is that common people used pounds (when they had them)
and the elite like Lords and Ladies uses guineas. Pounds weren't proper
money for the elevated.

 

[rickman]

On 17/02/2013 19:40, cameo wrote:



Even simpler is binary, like 1 inch, 1/2", 1/4" 1/8" etc.

And of course standard PCBs are both 1/16" and 1.6mm - spooky.

Miles are just hexadecimal kilometres. 80km is 50miles (0x50 = 80) and
30mph is 48kph (0x30 = 48). OK this may not always work...

Cheers

lol, does that mean 47 kph is 2A mph? It works when the single digit
miles are 0, in other words, when miles are multiples of 10.

 

[Tauno Voipio]

Part of the reason is that one nautical mile is (about) 2000 yards,
making lots of mental calculations much easier. It's formally defined
as 1852 meters but that's kind of unwieldy for most people trying to
do math in their head.

A nautical mile is a minute of arc on the great circle. It just
happens to be about 6000 feet.

 

[Jasen Betts]

Dropped at the same time from the same height, which would hit the
surface of the moon first?

With one dropped on the near side center, and the other dropped on the
far side center?

bot same time.

 

[Jasen Betts]

The only non-metric tool I still use consistently is a 7/16" wrench for
TV cable end-connectors. I guess I could also use an 11 mm metric wrench
which is about the same size. So I'm not even sure if those connector
specs are metric or not.

I looked at 3 datasheets on digikey, they all say the hex is 11mm.
the thread's not metric though, 3/8-32UNEF-2B

 

[Uwe Hercksen]

Metric is kind of nice because you can "make your own" when it comes to
magic sizes and stuff. Sometimes you want, say, a plate that's 1/4 or
3/8" thick, but it just doesn't look quite right -- visually appealing.
Instead, you could specify 5, 7.5, 10, etc. mm thickness, or other odd
values, assuming it's in stock of course -- and potentially get more
elegant proportions and whatnot.

Hello,

but if 1/4 = 6.35 mm is too thin and 3/8 = 9.53 is too thick, there is
also 5/16 = 7.94 mm or 9/32 = 7.14 mm.
If you want something like 5 mm, you may specify 2/10 inch which is 5.08
mm. 4/10 is 10.16 mm and 3/10 is 7,62 mm.
If they want to divide by powers of two, no problem, 13/64 is 5.16 mm.
19/64 is 7.54 mm. If more precision is needed, 1/256 is 0.09921 mm,
50/256 is 4.96 mm.

Just a little flexibility.

Bye

 

[Spehro Pefhany]

I looked at 3 datasheets on digikey, they all say the hex is 11mm.
the thread's not metric though, 3/8-32UNEF-2B

Yup. Most are dimensioned in hard metric (11mm across the flats).

Pomona's data sheet shows 7/16, which they dimension to 0.43 in
decimal inches (rather than 0.4375), and convert to metric at 10.92
(7/16" is exactly 11.1125mm). Sigh.

http://www.pomonaelectronics.com/pdf/d6709_001.pdf

FWIW, the nominal dimension given on hex nuts seems to be the maximum,
with tolerance allowed on the less-material side. I'm sure there's
some DIN standard, as there is a standard for Imperial dimensioned
external flats.




Best regards,
Spehro Pefhany

 

[SoothSayer]

Yup. Most are dimensioned in hard metric (11mm across the flats).

Pomona's data sheet shows 7/16, which they dimension to 0.43 in
decimal inches (rather than 0.4375), and convert to metric at 10.92
(7/16" is exactly 11.1125mm). Sigh.

http://www.pomonaelectronics.com/pdf/d6709_001.pdf

FWIW, the nominal dimension given on hex nuts seems to be the maximum,
with tolerance allowed on the less-material side. I'm sure there's
some DIN standard, as there is a standard for Imperial dimensioned
external flats.

Even more fun are Allen keys and hex keys. Those generally require
the utilization of the exact correct and proper tool to properly torque
the fastener and also not ever damage it.

Even with a Philips head screw, one should use the correct size, and
make sure the insertion force is applied correctly before torqueing in
either direction.

 

[Spehro Pefhany]

Even with a Philips head screw, one should use the correct size, and
make sure the insertion force is applied correctly before torqueing in
either direction.

Not to mention the Japanese standard (JIS) "not quite" Phillips head
that doesn't properly fit Phillips drivers. The JIS screws usually
have a dot on the head. The Japanese design depends on torque limiting
in the driver, wheras the older Phillips was deliberately designed to
cam out.


Best regards,
Spehro Pefhany

 

[Syd Rumpo]

On 18/02/2013 13:47, SoothSayer wrote:

Even more fun are Allen keys and hex keys. Those generally require
the utilization of the exact correct and proper tool to properly torque
the fastener and also not ever damage it.

A company I worked for which sold serviceable equipment partly to the US
had a policy of slotted screws only to save grief.

Cheers

 

[SoothSayer]

wheras the older Phillips was deliberately designed to
cam out.

Exactly, which not many know.

Not now, however. One is supposed to attempt to keep the screw head
pristine. that requires strong insertion force and a proper torque
limiting tool.

Nealy all "cam out" events also include a "buggered up" screw head
thereafter.

 

[Richard Henry]

I think I discussed this recently in one of the groups.  I remember
distinctly (or as well as I am capable of remembering) that in the 70's
we agreed to move to metric coordinated with Canada.  It was a
multi-step program with information and education being the first two
steps.  We even required the US auto makers to add metric to the
speedometers.  But when it came to actually changing something (I think
speed limits was the first thing to change) we told Canada to go on
without us and we'd catch up... which we *never* did.

I expect there was too much push back from the average Joe.  Heck, I
worked at a company just a few years ago that made push to talk radios
for the US military.  I was surprised that the mechanical engineers were
still using inches and converting all the metric stuff rather than doing
it all in metric!

Converting is inevitable, but perhaps not until it starts to make an
economic impact.  By then China will be running things and we will just
be the tail on the dog.

I once found a US Army specification for a piece of electronics
equipment that listed the maximum weight in grams and the maximum
dimensions in inches.

Off-topic a bit, but I have copies of two successive pages in a US
Navy spec. On one page, all that is written except for the document
header and page number is "This page intentionally left blank". The
next page just has the document header and page number.