Naming decimal places in the shop

jwalkerwade

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This feels like a stupid question, but I don't care.

Im new in this field of work so bare with me!

Can someone explain the proper way of naming decimals. Like, other than the obvious: "point 123".

Are they different in a machine shop than in a math class?

Im pretty much just confirming this for an old-timer stuck in his ways lol. I need help explaining this to him. If you could name a few for me I would greatly appreciate it!
 
The main thing to remember is...a tenth is not .1, it's .0001. and .7 is not seven tenths, it's seven hundred thousandths. Thats all you need to know...now go make chips. :))
 
See foot in mouth!! I wonder why they teach us in school that .1 is a tenth!!!! Oh well, understood... Thanks!
 
So it goes

.100 = one hundred thousandths
.010= ten thousandths ?
.001= ?
.0001= a thenth
 
So it goes

.100 = one hundred thousandths
.010= ten thousandths ?
.001= ?
.0001= a thenth

.100 = one hundred thousandths (100 x 1/1000")
.010= ten thousandths (10 x 1/1000")
.001= one thousandth (1 x 1/1000")
.0001= a tenth or one ten thousandth (1 x 1/10,000")
 
Last edited:
.001 == a thousandth

0.0001 is really "one tenth of a thousandth", or "one ten thousandth", but because machinists (well those using using the "English" system at least) typically work in thousands of an inch, we have developed this shorthand where everything is based on the number of thousands of an inch.

Now the whole thing is different in the rest of the world (you know the countries that are not one of the 3 holdouts that still use the English system, yes, I live in one of those countries...). Maybe someone who works in metric will describe the terminology there...I'm a bit curious now.
 
Yes, different terminology in different areas. The "micron" for example means a few different things... In pure science it's one decimal millionth of a meter (1x10[SUP]-6[/SUP] meter = 0.000039 inch). In some areas it also means 1/25 of 0.001 inch which is 0.00004 inch (close but not exactly equal to the pure mathematical definition). In any event, it's a small amount and all visible light have wavelengths in this range (actually it's around 400 to 700 micrometers). Single digit micrometer "light" is not visible to humans and is actually in the low end of ultra-violet which is only visible to honey bees and other insects. If you've ever milled a piece of metal and can see rainbow colors coming off the reflection, the individual grooves in the metal which cause that effect are on the order of that amount of distance.

FWIW, I have a measuring device that can measure down in that range and this is what it looks like... As a practical matter, this will never be used to make such critical measurements but, if I were in the business of making Grade A gauge blocks, it would be useful. FWIW, these units cost many thousands of dollars and I happen to see this one at a price I couldn't pass up... The granite block it's sitting on pales in comparison to it's level of accuracy. If you look at the bottom graduation line, you will see each line represents 0.00001".


Mitutoyo.JPGMity Fine Measure.JPG

Ray

Mitutoyo.JPG Mity Fine Measure.JPG
 
Ray, I hope you have climate control in your shop if your planning on using that.
 
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