When did metric take over?

[Firebrick43]

I worked for a couple German manufacturers as well as with many other equipment manufacturers, the only metric fittings I saw were for the hose to the fitting, the fitting to the equipment was always G or R type fittings, and the R type was maybe 5% of the time. It would be nice if they switched to metric threads so common taps could be used, but I think there is so much equipment out there with the G/R type fittings that it will be slow to be adapted. NPT fittings work close enough in some applications, but if you want any pressure rating, you need the proper fittings and threads. I’ve spent plenty of time tracing leaks that came from the incorrect fittings or threads being used.

I’m surprised you find tooling and fittings difficult to find, McMaster-Carr and Swagelok have plenty of offerings for fittings, and Whitworth tooling doesn’t seem difficult to find. The larger sizes are not as common but I never had an issue getting what I needed for standard pipe sizes.

The whitworth tooling is not hard to find. What I am talking about is actual metric fittings with metric threads, not whitworth threads like german G series. The port face/step drills were the tough ones to find, not the taps.

The ports are identified by a ring around the port

 

[higgite]

The American general public will accept metric as our national system of measurement right after we accept soccer as our national pasttime.

Tom

 

[pontiac428]

And here I was thinking G-thread was BSPP and not whitworth all along. I'll be dipped, it's a 55 degree thread, so whitworth it be. And BSPP. It's both. They're the same!

 

[Bone Head]

Metric, sae, metric, sae...look at your ratchets, breaker bars, socket sets. Regardless if your sockets are sae or metric, they're all 1/4" drive, 3/8" drive, 1/2" drive...

 

[Ischgl99]

The whitworth tooling is not hard to find. What I am talking about is actual metric fittings with metric threads, not whitworth threads like german G series. The port face/step drills were the tough ones to find, not the taps.

The ports are identified by a ring around the port

Parker Hannafin sells the porting tools for that specification. Other fitting manufacturers probably sell them too. I thought Swagelok had them when I looked many years ago, but don’t see them in their catalog, so not sure if my memory is correct.

 

[great white]

I think guys are getting too hung up on metric vs standard/imperial argument.

It's not about which is better, it's about standardization.

You only have to google "gimli glider" to get an example of what I'm talking about.

The helo I used to fly was the EH101. A UK/Italy built aircraft. When we ordered them, they said they could convert the dispalys from metric to standard, but it woudl cost XX millions to do it (total software re-write). We said no thanks and had it delivered in metric. Now, avaiation is mostly carried out in standard measurements, but in the aircraft and operating it, we only needed to know the number a system should display and we generally didn't care what the measurement was as long as it was still in the "acceptable" range. 5,000 kgs, could have been 5000 lbs or 5000 chickens fro all we cared. As long as 5,000 was the number we needed, the rest doesn't matter. I know when I was balancing fuel load, I didn't care if it was displaying lbs or kgs in the cockpit, just that the tank level number were matched for proper C of G. When I did pay attention to the units was when we woudl take on fuel from a source, had to make sure we got what ewe asked for. But then again, the cockpit gauge was the final go/nogo criteria, so we didn't go if the number wasn't what we needed. Just recall the fuel truck and top it off.

Doesn't matter what system you use, just that you know and understand the system you are using and that OTHERS you are interacting with are using the same system....or know that your measurements are not the same measurements they are using.

USA is a big country (both population and ecnomy), but compared to world population, it's pretty small. The world, for the most part, uses metric. So who should give up what and who should standardize to what system?

 

[Parlo]

Volumes can be tricky.
In the UK to remember the weight of water we used the rhyme - "a pint of water weighs a pound and a quarter". This is because a gallon weighs ten pounds and a pint is 20 ounces.
In the US a gallon weighs 8 pounds because a pint has only 16 ounces.
This caused a bit of confusion with my car MPG display that had to be changed to UK gallons for the correct MPG reading.

 

[Jeff.64]

That is not true, that information came from a poorly researched article and is constantly re-reported by metric propagandists.

They ignored countries like the UK because they are "officially" metric yet like the US still use a lot of Imperial (correct term in the UK) measurements, like the USA uses US Customary unit (not Imperial they are different systems with much in common). Funny thing is the USA is also officially metric, US Customary system has been defined by the metric system meter and kilogram since 1893. The UK did not define Imperial measurement with the metric system until 1985.

Thanks for the correction. I guess repeating what you heard from "reliable people" over the years can get you into trouble. I just did a search for "countries that use imperial system" and was unable to find the contrary info you of which you write. If you could post a link or two, that would be great. I know some people at work with whom I'd like to share the information. I really hate the idea of having propaganda in place of facts in my head. I think someone of note said something like "It's not the things you don't that get you into trouble, it's the things that you know for sure that ain't so that do" Twain? Thanks again.

 

[ChazzC]

I use Decimal Imperial for the Mill and Lathe and Metric for the 3D Printer. No difference to me in one being easier or harder. I do have to slow down a bit when I have a part that needs operations on both the 3D printer and the Mill/Lathe as that is when I need to do a conversion.

The “system” I use for my designs depends on both the raw materials being used and the end use of the item. In the U.S., many raw materials come in US/SAE/Imperial dimensions - think flat, rectangular & angle stock. Overall finished length will be in fractional inches, unless it’s critical. Round bar is available in both inches and mm, so I buy whatever will work. If I’m making something for use with a metric machine, I’ll use metric dimensions and hardware; otherwise I’ll use what makes sense.

Yes, this leads to mixed systems within a part (1” x 1-1/2” x 1/8” x 7”angle with 2, #7 through holes spaced 345mm on center), but that’s what makes it fun.

Oh, while I have metric drill bits & end mills, most of the time I use fractional end mills & drill bits from my “standard” 115 piece set as replacements are more readily available and cost less, reserving the metric tooling for those applications that require their use.

 

[Aaron_W]

Thanks for the correction. I guess repeating what you heard from "reliable people" over the years can get you into trouble. I just did a search for "countries that use imperial system" and was unable to find the contrary info you of which you write. If you could post a link or two, that would be great. I know some people at work with whom I'd like to share the information. I really hate the idea of having propaganda in place of facts in my head. I think someone of note said something like "It's not the things you don't that get you into trouble, it's the things that you know for sure that ain't so that do" Twain? Thanks again.

Well the Wikipedia page on the Imperial system is a start, it provides a history of the move to metric in the countries that used the Imperial system. Most of the ex British colonies continue to use a mix of metric and other, India, Australia and New Zealand having made the most progress towards full metrication.

Imperial units wikipedia

Contrary to popular belief the US does not use the Imperial system, it is a special snowflake and uses US customary units, which are similar but have different values. For example the US gallon is smaller than an Imperial gallon. Because of their proximity to the US, Canada and many Caribbean nations use a mix of both Imperial and US Customary units poor buggers.

There is also the issue of "official" vs common usage, the USA in fact was an early adopter of the metric system passing a law in 1866 making the metric system legal for use in commerce and in 1893, US Customary Units were redefined utilizing the metric system as the base (an inch is defined as being 25.4mm, that is not simply a conversion). So from a legal sense the US is very much a metric nation, but in common use much less so.


The problem with the only 3 countries are not metric thing is it was done as a got ya piece. Like the old have you stopped beating you wife gag.

The authors defined "not metric" in a narrow way that made their statement true, but misleading. You need not look any farther than a highway sign to see this, as UK highways are still signed in miles.




I am not a metric hater but I don't like deception, and the "only 3 countries" thing irritates the crap out of me. Not surprisingly in a country founded on "you are not my mother" the government has taken a soft approach to conversion.