Thread: But we did agree to disagree

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Almost friendly discussion lead to- Is .02 the same as.020. I say yes , he says no.

i see both as " twenty thousandths " .. when used in a machine shop venue the amount of #`s after the # 2 is indicative of the amount of tolerance that is considered to be figured in .. hence .02 may have plus or minus 10 thousandths where .020 would have plus or minus .001 thousandths

In theory your friend is right. .02 has only two digits to the right of the decimal place, which implies that the reading is in hundredths of an inch, so it could be expressed as two one hundredths of an inch. .020 has three digits to the right of the decimal place, which implies that the dimension is in thousandths of an inch---so would be expressed as twenty thousandths of an inch. As we all know, anything measured in thousandths is ten times more accurate than something which is measured in hundredths.---It gets kinda like fighting over how many angels can dance on the head of a pin---but---theoretically--your friend is correct.

$0.10, 10 cents, or a dime.......all are valued the same, but expressed differently given the supporting context of the situation. I'm with Brian on this one.

In the machinist trade, thousandths is the language.

You could say 1/8th inch....but to a machinist, it will always be .125. You want to be understood, and to communicate what you mean, without being misunderstood, do it in the common terms.

I spent a number of years working in the trade, so I am not just debating the point.

HotRodPaint:I am like you I spent many years working in the Tool & Die Industry.Normally when you saw a two place decimal (.02) you could hold that tolerance easy,usually + or - .010.When you saw a three place(.002) decimal it was usually + or - .005 which required a little thought.When you saw a four place decimal (.0002) it was usually + or -.0001 and you were usually grinding to hold that tolerance in a controlled environment with calibrated measuring instruments. I know greater tolerances are attainable but they never came my way.

I'm in Tool & Die, I build Investment Molds, and specialized in airfoils, Turbines & turbo's. We have lost most of our tolerance yrs ago, we have to be with in .005 in one place (.1), with in .001 on two place (.12), with in .0005 on three place (.123), and with in .0003 on four place (.1234) @ 72 degs.
Years ago on a .1 Number, using a scale was almost close enough, and a dial Veneer (dial very-near) was used on .001 (I have always used a micrometer) Give 10 people a veneer and you'll have 10 different numbers.

Pat

.02 and .020 are the same measurement. Tolerance is determined by the engineers.

Maybe I am out of touch. I worked for Hyster Corp. making production parts, and obsolete replacement parts. After that I worked for a foundry, machining mining machine components. I've never even seen a drawing done in hundredths of an inch, and the tolerances were usually spelled out, or an engineer would tell me what he wanted. The most exteme tolerances I worked in were .0003

In school I was taught that .020 is two one hundreths and .020 is twenty one thousanths. They are both the exact same thing. You can say Tomato or you can say Tomatoe. Same thing.

.02 and .020 are NOT the same.

If something measures out to .02 it might be anywhere from .02 - .029

.020 is anything from .0201 to .0209

Your friend thinks it doesn't matter? Then tell him to check the prices at the gas pumps. They COULD leave it at .01 but they don't. they take it to .001 and they do it to make MORE MONEY.

.02 ends because there is only an expected 0 for infinity
.020 """ """ """ """ _______________________""""""""" etc
they are the same measure ..
when you make it .021111111111111 then it is not the same measure as
.0209999999999999...

In my GE machining history a long time ago and then my design positions - our design practices said .02 meant .020, .0200 or .02000 or for as long as you wanted to add zeros to the end. There was no tolerance implied. If there was a tolerance, it was either stated in the title box on the front of the drawing (usually another drawing, called a spec) or at the specific dimension itself if it deviated from the spec drawing allowance. It didn't mean .021, .022, .0201 or any other dim.

Many companies have design practices that deviate from this and do allow you to make assumptions - but you sure don't have that luxury on a 43 inch long staem turbine blade or 100,000 pound (plus) shaft that rotates as high as 5000 rpm or more. If you can find a copy of Machinery's Handbook, my newest is the 21st edition(old), there are about 50 pages of a chapter, Allowances and Tolerances, and another 10 of measuring instruments that are guaranteed to induce sleep.

Denny---Somebody is pulling your chain!!! Gas at the pumps in ontario is $1.05 a litre for the cheap, low test stuff. that works out to 1.05 x 3.78543=$3.97 per US gallon. --Brian

Originally Posted by Dave Severson

.02 and .020 are the same measurement. Tolerance is determined by the engineers.

Dave you are right,it's just a number.The designer determines where you should be tolerance wise w/n that number.

Years ago at IBM they tried to set an example to the world .Go with the Metric System it's simpler to use.We did double tolerancing to try and sell the idea.Result- Lots of training and money wasted.Most of the Tool Makers and Machinist hated it. I don't know what system is being used in Industry,but with all the work (jobs) going off shore (primeraly China) the system of choice I think would be Metric.