What Do All Those Zeros Really Mean?

Cactus Farmer said:
Now , that is funny. And a better explanation than I ever saw before. I am 66.0000000 years old. BaBaBaBahahahaha
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Wow, great timing Cactus Farmer! That last decimal place in your age represents 3.15 seconds.:laughing:
 
As a professional land surveyor in a previous life, I heard various discussions concerning accuracy versus precision. Here is a quick and dirty example of the distinction: http://www.honolulu.hawaii.edu/instruct/natsci/science/brill/sci122/SciLab/L5/accprec.html

There are plenty of other, more in depth webpages on this, but you get the idea.
I am assuming from previous posts in this thread that the precision being discussed relates to resolution of the DRO or vernier scale.

I do agree with the OP, dealing with most of our day to day measurements to greater than 0.001" is neither easy nor necessary for hobby machinists.

Dan
 
The real joke happens when,using a CAD program, you convert from imperial to metric and you let the presentation to
the 8 decimal digits.Once, making a printed circuit board,i was asked to position two holes at a distance of 1.96850393
inch.It was actually 5cm.The man insisted to this "specification" because the 'computer had calculated it precisely'.
Ariscats
 
± 0.000 is fine (but usually unnecessary IMO) as long as it is accompanied by the appropriate GD&T notations. I have seen it a number of times.
 
It drove my crazy trying to hold a dimension using DRO with .0005 readout. Every time I tighten the table clamps the setting would change on those old machines. I would put a piece of tape over the last digit.
 
Did a drawing package for a customer of mine. All the proper dimensions and tolerancing were used. Months later, started getting emails from their machine shop on the other side of the world. "We can't machine to these dimensions, and the tolerances, OMG!". Found out, my customer has taken my drawings to another vendor and had them put in Solidworks. Solidworks pretty much has one way to deal with tolerances, either every dimension is +/-.0005" or +/-.005". Can't do +/-.010". Oh, some of the dimensions I had place on the drawings were nowhere to be found! They placed all the linear dimensions from one end only, the end opposite of where a cutting tool starts!
 
I'm an old carpenter, an aged aspiring machinist. 40 years ago, we built a prototype cabinet for a Sony TV. (It was obsolete before it went into production.) The engineers, from Japan, had 6' long calipers measuring our cabinet, scowling and expressing their disapproval of our tolerances.. A 64th of an inch (how many thousandths is that, is pretty good in a cabinet shop.
 
4gsr said:
Did a drawing package for a customer of mine. All the proper dimensions and tolerancing were used. Months later, started getting emails from their machine shop on the other side of the world. "We can't machine to these dimensions, and the tolerances, OMG!". Found out, my customer has taken my drawings to another vendor and had them put in Solidworks. Solidworks pretty much has one way to deal with tolerances, either every dimension is +/-.0005" or +/-.005". Can't do +/-.010". Oh, some of the dimensions I had place on the drawings were nowhere to be found! They placed all the linear dimensions from one end only, the end opposite of where a cutting tool starts!
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That is a shame they would do that to your finished drawings. Those machinist were blaming you for all errors. I had a few prints sent back the project designer for clarification. I have messed up some short run production parts because I misinterpreted a print.
 
I just installed a DRO for a mill at work, the 10uM scales were .0001 and the 5uM scales were .00001 on the Newall DP7 DRO dispaly.....
 
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