[musicmkr]

This has confused me for as long as I can remember. By definition a "tenth" should be equal to 0.1" or one tenth of an inch. However in the metal working world a "tenth" seems to always indicate 0.0001" which is one ten thousandth of an inch. I guess it is also technically one tenth, of one thousandth of an inch.

It would be like the construction trade using the same term to describe both one inch, and one foot.

Is this just some short hand slang that is trade specific? Or is this standard terminology?

[mrainey]

I guess, with the basic unit of U.S. machining measurement normally being a thousandth, a "tenth" refers to a portion of that basic unit.

Sounds logical, but I don't really know.

[Mcgyver]

a tenth of thousand of an inch, .0001. the 'thou' is the (imperial) machinists standard unit, so in that context you can see how calling it a tenth makes sense. it is very small! most can work to a couple of tenths or at least to within half a thou, but to work to .0001 consistently takes some expensive machinery and climate controls, at least in a manual environment.

[ynneb]

Make life simple and accept Metric.
Its just soooo much easier.

Sorry I do not know the answer. Our country has embraced Metric since the 70s and we have not looked back.

I dont know about USA, but the moment Metric was introduced, our primary schools only taught it.

[mxtras]

A tenth to me means .1mm but I have been a metric guy for 25 years. Machining in inches for me requires conversion - I see everything better in Monkey Meters.

Scott

Scott

[Chris D]

This has confused me for as long as I can remember. By definition a "tenth" should be equal to 0.1" or one tenth of an inch. However in the metal working world a "tenth" seems to always indicate 0.0001" which is one ten thousandth of an inch. I guess it is also technically one tenth, of one thousandth of an inch.

It would be like the construction trade using the same term to describe both one inch, and one foot.

Is this just some short hand slang that is trade specific? Or is this standard terminology?

Machinists never really work in tenths of an inch as in .1". Rather, we work in much smaller increments, like thousandths of an inch. So, as time went on in the shops, the terminology followed what we do.

For example, .125 is spoken as "a hundred and twenty five thousandths"
You would not say "one tenth and twenty five thousandths"

So, the thousandth of an inch is primarily the "base line" of reference. So, if you here someone say " your 5 tenths oversize " and you are in a machine shop, you can pretty much bank on it they are referring to tenths of a thousandth .0001"

so, for clarity of shop talk....

.1000" = hundred thousandths of an inch - or simply a "hundred thou"
.0100" = ten thousandths of an inch - or simply "ten thou"
.0010" = thousandth of an inch - or simply a "thou"
.0001" = tenth of a thousandth or simply a "tenth"

hope that helps you!

Chris

[Klox]

The imperial system is so confusing!!!! Here in RSA we're also on the metric system. As Benny says, "Its just soooo much easier."

[Chris D]

The imperial system is so confusing!!!! Here in RSA we're also on the metric system. As Benny says, "Its just soooo much easier."

They are both easy, once you understand them. Putting a man on Mars and brain surgery is difficult, counting and working with basic decimal numbers is easy by comparison. Refusal to learn the system makes it difficult too, which is one of the reasons the U.S. is stull using the imperial system.

Chris

[ViperTX]

might as well throw in the "hundredths"....0.00001....guess we could continue...I think the next one is "one thousandth"..0.000001...."one ten thousandth"...then is it micron??

[CJL5585]

Well, when I was growing up, the only thing taught in public school was the Imperial system.

However, some years later I went to work for an European Laser Manufacturer and everything was metric, so I got really good at conversion, that is when it dwelt with lasers and equipment.

I still have a problem with metric weather forcasts. Once in Canada, the weather forcast was 1 cm of ice covered with 15 cm of snow mixed with sleet. Just thinking that was pretty small metric measurements, I went to my rental vehicle in a short sleeve shirt to find every door frozen shut, and the doorlocks also frozen. It did not take me long to make conversions before going outside in a short sleeve shirt in the wintertime.

The actual problem that I have is that I reason in Imperial, and have to make conversions either in my head or with calculator. I do not reason in metric, although I can easily convert a reasonably large metric measurement to Imperial in my head.

It all relates to what you were taught in grade school. That seems to be what one relates to later in life.

Jerry

[trilect]

Shooting myself in the foot but I remember being taught

.1 = tenths
.01 = hundredths
.001 = thousanths
.0001 = hundred thousanths

etc.

[miljnor]

just think of it this way. People are inherintly lazy, so they take short cuts and abbrieviating something is a short cut. And since most people talking about machining assume you know something they Abrev. and instead of saying a tenth of a thousanth of an inch they abrev. So I.C. IMO this is just an Abrev of The above thus a tenth is a tenth but with a machining frame of REF. LOL


Meteric is far easier to understand Hands down. But if you were a world power and wanted to stay ahead why not throw one more wrench in to the works and use a system that gives everyone else headaches And all the while their way of doing things is SOOO easy to understand. Its like one more level of encryption, granted it's not hard to understand but laziness being hardwired it does tend to give the metricly minded headaches! But we love you guys anyway

[Geof]

Shooting myself in the foot but I remember being taught

.1 = tenths
.01 = hundredths
.001 = thousanths
.0001 = hundred thousanths

etc.

.0001 is ten thousandths (which is a significant difference).

"Tenths" meaning "one tenth of a thousandth of an inch" is industry specific and much easier to say. Carpenters don't need a shortened term because their normal unit of precision in an eighth which is already easy to say

[mxtras]

It is easy on a metric mic to measure .01MM which equals .000394". Machining in microns on the metric system is actually quite easy and common.

A micron is a metric measure unit equivalent to .001MM or 0.0000394 inch.

It is easier to measure a gnat's arse using metric measuring equipment.

Not to mention they use 60 degrees for their threads....where in the heck did they come up with 55 degrees for UNC, UNF?

I have machined and manufactured in both systems but prefer metric for the accuracy and simplicity of the unit of measure.

Scott

[Geof]

Not to mention they use 60 degrees for their threads....where in the heck did they come up with 55 degrees for UNC, UNF?
Scott

UNC and UNF are 60 degrees; 55 (or was it 57?) was Whitworth and I think BA.

[mrainey]

Whitworth = 55
BA = 47.5

[mxtras]

Ooops - ....confused as usual. Sorry!

NPT is 55, right? One of the commonly cut threads is 55 degrees, darn it!!!

Scott

[cadman]

The way I learned it, in high school math a "tenth" is .100, and in machine shops a "tenth" is .0001.

[Geof]

Ooops - ....confused as usual. Sorry!

NPT is 55, right? One of the commonly cut threads is 55 degrees, darn it!!!

Scott

Nope! NPT is Unified thread form but on a taper with the thread angle measured to the centerline not to the taper. The only other thread angle that I know is acme at 15 degrees; although if you use the same measuring protocol as for unified I think you should call acme a 30degree thread angle. Unified is 60 degree included angle and acme is 15 degree flank angle.

And I apologise for partially hijacking the thread but at least I am still on the topic of arcane nomenclature designed to confuse the non-initiated.

[mxtras]

Yeah - I am guilty of hijacking - sorry.

Back to the topic - what is a tenth? It's .1 to the majority of the world but .0001 to American machinists.

Scott