Please explain this Metric thread size

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The threads on a MIG Welder tip are listed as:
M5 x .8 thd
I always have problems understanding metrics.
I know that a 1/4 x 20 bolt means 1/4 inch diameter, 20 threads per inch. That's so easy.
Then they shove metrics into our lives and all hell breaks loose...
I'm going to take a guess,
The "M" means METRIC
The "5" means 5 milimeter (mm)
The ".8" I dont understand at all. It's surely not .8 threads per inch, or that would mean less than one thread per inch.
I'm sure the "thd" means THREAD
I googled this and 5mm is 0.197 inch, which needs a 4.20mm drill size. (NOT what I was looking for)!
Damn, I hate metrics . . . . . . . .
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On 05/09/2016 09:27 PM, snipped-for-privacy@unlisted.moo wrote:

Damn, I hate British Standard Whitworth...
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On Mon, 09 May 2016 23:27:58 -0400, snipped-for-privacy@unlisted.moo wrote:

It is easier than you think The thread pitch is .8mm
The rest of the world would ask WTF is an inch?
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snipped-for-privacy@unlisted.moo wrote in news:veq2jbhppenr460r0ubihpc4qoe1uvglfo@ 4ax.com:
[...]

How the heck old are you, anyway?? I'm almost 58, have lived in the U.S. my entire life, and I was taught the metric system in grade school. You must be quite a bit older, *and* have never had any education whatever in the sciences. *Everything* is metric in a laboratory. [...]

Get a newer truck. I've owned three vehicles which were mixed, all of them from the mid- 1980s. My 1996 Buick was all metric. So is my wife's 1998 Mustang.

No, not really, it only seems that way to people who don't understand the metric system. Without looking it up: - how many yards in a mile? - how many teaspoons in a cup? - how many gallons in a bushel? - how many gallons in a cubit foot?

Apparently it has not occurred to you to keep your metric wrenches in a different toolbox...
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doug_at_milmac_dot snipped-for-privacy@example.com says...

The you have to carry 2 tool boxes for many jobs. I remember working on a car years ago and part of it was SAE and part Metric.
Not sure of the size of the spark plugs, but I bought a Datsun and the first time I went to change the plugs I thought I would need a metric plug socket. Asked the man at the Autozone parts counter and he did not know. We took out a plug and started checking wrenches,. Found one that was a loose fit. Then on a whim I checked a SAE plug socket and it fit just fine. Did not need one as I had some at home.
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On 05/10/2016 12:46 PM, Ralph Mowery wrote:

A 9/16 plug socket is close enough for government work on 14mm plugs.
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wrote:

Now that is an excellent idea. Thank You!!!
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wrote:

I have a bunch of metric snap on sockets and they all have knurled rings around them to differentiate from SAE
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On Wed, 11 May 2016 01:25:58 -0400, snipped-for-privacy@aol.com wrote:

That works if all your tools are the same brand - not all companies make the differentiation in the same way - if at all.
Another solution is red or blue or black chrome for one or the other - again only if allyour metric or SAE tools are the same.
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snipped-for-privacy@aol.com wrote:

And you can divide the countries of the world into two groups: Those that use the metric system, and those that have been to the moon ;-)
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On Wed, 11 May 2016 13:24:02 -0500, Mark Storkamp

... Except NASA is on the metric system. They have been since they crashed a probe on Mars because someone was confused.
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On Wed, 11 May 2016 13:24:02 -0500, Mark Storkamp

Russia uses the imperial measurement system??? Russian measuring system of length is metric (centimeters, meters and kilometers), so they do not use inches or feet in Russia. They use grams and kilograms as the measuring system of weight, and Russians are not familiar with ounces or pounds. Liquids are measured in liters, rather than gallons, though strangely enough alcoholic drinks are measured in grams. Do not forget about this when you buy gasoline in Russia, as it is also measured in liters (there are about 4 liters in a gallon). Unlike in Fahrenheit-oriented countries, temperature in Russia is measured in Celsius, or Centigrade (which is a former name for Celsius). Or order to convert Fahrenheit into Celcius, use the following formula: Celsius Temperature = (5:9) x (Fahrenheit Temperature-32).
So, I'd have to say your "daffynition" is "daffy"
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On Wed, 11 May 2016 16:18:36 -0400, snipped-for-privacy@snyder.on.ca wrote:

Perhaps he should have said "came home from the moon" because if a russian ever got there, he is still there.
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snipped-for-privacy@snyder.on.ca wrote in wrote:

[,,,]

Russia has been to the moon?????
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On Fri, 13 May 2016 01:31:24 -0000 (UTC), Doug Miller

Only three countries have ever soft-landed on the moon, the United States, the U.S.S.R. and now China. Of those 3, only the USA has landed a live human on the moon. So it depends on your definition of "been to the moon"
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On Fri, 13 May 2016 00:57:25 -0400, snipped-for-privacy@snyder.on.ca wrote:

That is why I said "been back from the moon. Everything the russians ever sent to the moon is still there.
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Uncle Monster posted for all of us...
be.com/watch?v=otCpCn0l4Wo

was a most interesting project. The engine block was part of the frame. The diameter of the threaded part of the spark plugs was the largest I've ever seen. I could remove a spark plug and stick my finger through the hole in the cylinder head. The block had sleeves that we replaced and the darn pistons had 4 rings. I've never seen something like that then or since then. It was a fun job to remove the engine from the tractor, rebuild and reinstall it. I just remembered, we took the generator off and installed a Chrysler alternator thus converting the tractor to 12 volts. ^_^

Have you noticed my new kindness?
--
Tekkie

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Uncle Monster posted for all of us...

gray tractor and would do just about anything you asked the old critter to do. The utter(pun intended) simplicity of the tractor made it easy to main tain. It had an updraft carburetor and would run on anything that was as vo latile as gasoline. I think the moonshiner down the valley had one that he ran on his homemade fuel. We rebuilt the old tractor's engine back in 1970 and it

The diameter of the threaded part of the spark plugs was the largest I've ever seen. I could remove a spark plug and stick my finger through the hole in the cylinder head. The block had sleeves that we replaced and the darn pistons had 4 rings. I've never seen something like that then or since then . It was a fun job to remove the engine from the tractor, rebuild and reins tall it.

lternator thus converting the tractor to 12 volts. ^_^

e_Museum_August_2015_14_(1949_Ferguson_TO20_tractor).jpg

Nutz?
--
Tekkie

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On 05/09/2016 09:27 PM, snipped-for-privacy@unlisted.moo wrote:

FWIW, 4.2mm is a lot easier to find in a metric drill index than having to hunt thru fractional drills, number drills and letter drills.
I think the real problem is that US manufacturing doesn't know whether to shit or get off the toilet.
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On 5/10/2016 4:18 AM, Jack Hammer wrote:

I had to get used to metric about 25 years ago when I changed jobs. IMO, it is easier to use once you use it. The rest of world is trading amongst itself and the US is sometimes left out because we are different.
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