Converting to Decimals

How many decimal places for microinches. How many decimal places for millionth's(How to write 200 millionth's).

First of two simultaneous responses 2003

Platers have their own lingo for such measurements. We refer to plating thickness as "tenths" which are actually ten-thousandths of an inch. That is 0.0001 inch is called "one tenth" by platers. The term "tenth" actually refers to one-tenth of a mil with a mil being 1/1000".

Now to answer your specific question, a millionth of an inch is the same as 1 microinch. One hundred microinches is one tenth to a plater, thus, one millionth of an inch or a microinch is written 0.000001". With so many zeroes, you can see why saying one microinch is easier!

200 microinches = 2 tenths = 0.000200 inch

Second of two simultaneous responses

Millionths of an inch and microinches are the same thing. The first digit after a decimal point is tenths, then hundredths, then thousandths, then ten thousandths, then hundredthousandths, then millionths. So 1 microinch would be 0.000001" and 200 microinches would be 0.000200" which is the same thing as 'two ten-thousandths of an inch' or 'point 2 mils'.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey