totally confused over metric

[john.k]

Years ago I was given a very nice tape measure......one of the big 100 yard ones in a leather case with a brass folding handle.I used it for a few setouts.......and lots of snide comments...........finally figured it out.........the tape is in yards and feet........and what look like inches are actually 1/10 of a foot........So you can have metric in feet as well,as millimeters etc.

[Jeff Michel]

Spend some time in a machine shop that works in both systems, you'll have it figured out in about a day.

[William Yanda]

My high school algebra teacher told me in 1974 that by 1980 the United States would be totally converted to the metric system. I told him I did not think so. I guess I won that argument!

Sent from my SAMSUNG-SM-G930A using Tapatalk

Even then the whole country was using the metric system for time-hours and minutes.

[TRX]

.the tape is in yards and feet........and what look like inches are actually 1/10 of a foot........So you can have metric in feet as well,as millimeters etc.

Decimal feet. American industry used to run in fractions, mostly, as did government contracts. During WWI a coalition of Detroit manufacturers petitioned the War Department to be able to use decimal inches instead of fractional inches when filling government contracts. (decimal inches were something that Thomas Jefferson had advocated, long before...)

Companies like Ford held on to fractions for decades, which is why pre-WWII Ford service manuals specify dimensions in 1/128ths and such.

Then there are peculiarities like metric micrometers which read in 1/4 mm increments...

[john.k]

it took me a while to figure it out...just so unexpected..............finally the penny dropped when I couldnt find 11 inches on the tape......who d a thunk it?...........You lay out a $5000 concrete slab,and when poured its noticeably cockeyed.

[Larry Gibson]

The metric system is a communist conspiracy to corrupt the moral fiber of America's youth.

Note the attempted adoption of the metric system coincides with the beginning of the downfall of the American society.......just kidding...... but.......

[leebuilder]

I like the metrics, but when you build stuff that is 39,000mm long it's good to have a second set of eyes. I have come across fractional metric threads, never seen a lathe that would cut it. So time to get out goes-into-ta-matic and make due. I seen an Indian made mill that was graduated in 1/128ths.
I am sure there are many other unique items around ie Whitworth and BA.
Be well

[Kenstone]

Here's a useful online converter, it's free, down load it and create a shortcut on your desktop or task bar:
https://joshmadison.com/convert-for-windows/
Click on the yellow/orange download button, NOT the green one
Did I mention it's FREE

Edit: Use 25.4 for metric/inch conversions it's way more accurate than .03937.

[KCSO]

The same way a cap and ball 44 is really a 45. Or as Winchester put it, "All our 44's are really 43's except for the 38, which is a 40". Depends if you are calling it by bore or groove.

[DCM]

7.35 Carcno is much closer to 0.30 cal than the 7.62 we call 30 cal. 357Sig = 0.355" while 38 special = 0.357" 460Rowland=0.451" ...

[ANick57]

Here's a useful online converter, it's free, down load it and create a shortcut on your desktop or task bar:
https://joshmadison.com/convert-for-windows/
Click on the yellow/orange download button, NOT the green one
Did I mention it's FREE

Edit: Use 25.4 for metric/inch conversions it's way more accurate than .03937.

While 25.4 is indeed accurate, using .03937" per mm results in an error of .0000787 inches at one meter. Kinda tough to measure methinks.

[TRX]

25.4 came from the US Department of Commerce, to simplify conversion between systems in international trade.

It has had far-reaching consequences in chemistry and physics, where the rounding error invalidated much experimental data collected by people who should have known better...

[Dieselhorses]

I own a 12.7 mm S&W Magnum revolver. Believe me, it confuses me too.

[RED BEAR]

and the British have there own thread system for bolts and nuts.

[fast ronnie]

and the British have there own thread system for bolts and nuts.

Mauser large ring has a 1.1 thread that is 12 pitch 55 degree which is Whitworth. I had a very well known gun maker try to tell me it was metric. The machinery to build the original Mausers was purchased from England.

[nekshot]

Ok, ok, now i am really getting confused! I kinda think Larry might have a point, you know the globalization and all that was jammed down our throat. I really would like to open up a 7.2 x39 in a ar to 9mm but should it be a .356 or .366 diameter?

[nekshot]

dang meds!! 7.62x39 is what I meant in last post.

[Willbird]

Well some cartridge names are bore and others are caliber. .218" is the minor dia of many .224" barrels, hence the 218 bee and the 224 Valkrie can share the same bullets . Then some stuff is rounded up or down too. The 6.8SPC and the 270 both use .277 bullets. 6.8/25.4 = 0.26771".
.277 x 25.4 = 0.26771"
270 reamer pilot Nominal Pilot Size: 0.2692...dunno where they got the 6.8 from ....well some combloc stuff made for steel jacket bullets runs a bigger minor dia than typical USA designed stuff for gilding metal bullets.

[indian joe]

Mauser large ring has a 1.1 thread that is 12 pitch 55 degree which is Whitworth. I had a very well known gun maker try to tell me it was metric. The machinery to build the original Mausers was purchased from England.

That one has caused a lot of grief !!!! Whitworth threads are same TPI as National coarse all the way from quarter inch up to inch bolts EXCEPT for the 1/2 inch whitworth is 12 TPI and 1/2 inch NC is 13 TPI ----------why is that a problem ? Aussie system is based on English due to our colonial history - but most of our AG machinery imports last century came from north america - my first lesson came pulling the brake drums on a massey harris tractor - two 1/2 inch bolt holes in the machine to do it - easy deal - grab a couple 1/2 inch bolts -----------ooooops! 12 thread ina 13 hole they go about 6 or maybe 7 threads in before they seize up good - so a simple job those days ends with a trip to town to buy a couple of bolts or (as we did) NC tap and die ------later years we added metric machinery to the mix - more confusion !! Had a International 986 tractor once with a German Neuss motor (metric fittings) US made transmissions (National standard threads) Aussie built peripherals (half whitworth and half metric) to top that off you could not buy a bearing from the bearing supplies because International Harvester had a deal where they used special order bearings with metric outer and inch size inners (or vice versa)

[William Yanda]

My high school algebra teacher told me in 1974 that by 1980 the United States would be totally converted to the metric system. I told him I did not think so. I guess I won that argument!

Sent from my SAMSUNG-SM-G930A using Tapatalk

I remember that argument, and I chuckle every time I look through a catalog of mechanics tools and see the metric sockets offered in........wait for it...........1/2, 3/8 and 1/4 I N C H drive!