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12-21-2009, 01:25 AM   #11
Deanofid

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Re: Trying out metric

Metric? Have fun with it, Potman.
It's just for folks who don't know their fractions, you know...
(nudge, nudge, wink, wink.)

Dean

12-21-2009, 01:58 AM   #12
websterz

Join Date: Mar 2009
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Re: Trying out metric

Quote:
 Originally Posted by ironman Is that magic number .03037 or .03937? I just ate dinner and my brain isn't on the ball for thinking right now?
.03937

12-21-2009, 05:26 PM   #13
mklotz

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Re: Trying out metric

[pedant]

Actually, the magic number is 25.4, exactly. The inch is *defined* as 25.4 mm. Yes, that's right, the inch is defined in terms of the metric system. (As are many of the other basic units in the Imperial idiocy.)

1/25.4 = 0.039370078... is an irrational number. That means that the decimal representation goes on forever whereas the 25.4 representation is exact since that's how the inch is defined.

[/pedant]

Clearly, if one is simply estimating, none of this matters - calling a millimeter forty thousandths is good enough. However, if using a calculator, it's less keying to divide by 25.4 than to multiply by 0.03937. Further, most people seem to have less difficulty remembering 25.4.
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12-21-2009, 06:14 PM   #14
jimmyocharlie
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Re: Trying out metric

i work in both metric and imperial!

i run CNC's, some are programed in metric and some imperial!

altering an offset to take thou off, is either 0.001 or 0.025! it can make it an interesting night when you are running one of each

wheights still catch me out though, in England its all metric, doing the shopping online i've bought a Kilo of mushrooms (thats a LOT!), pounds and ounces makes sense, but Kilos..............................

12-21-2009, 06:22 PM   #15
mklotz

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Re: Trying out metric

Quote:
 in England its all metric
Come again?

Pints of beer, stones on the bathroom scale, and, IIRC, miles on distance markers?

Do you still use that hundredweight (cwt) that weighs 112 pounds?
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12-21-2009, 07:15 PM   #16
dieselpilot

Join Date: Jan 2009
Location: Chicagoland
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Re: Trying out metric

CNC runs in both. Just set G20 or G21 Right? I like metric. Too bad it's hard to find good metric lathes in the US at a hobbyist price.

12-21-2009, 07:33 PM   #17
potman

Join Date: Sep 2008
Posts: 54
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Re: Trying out metric

Being ignorant about such things....
What makes a lathe "metric"

Is it just the gearing for the screw thread, and
the calibration on the handwheels?

Or is there more to it ?

earl...

12-21-2009, 07:41 PM   #18
Noitoen

Join Date: Dec 2008
Posts: 621
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Re: Trying out metric

Quote:
 Originally Posted by potman Is it just the gearing for the screw thread, and the calibration on the handwheels? Or is there more to it ? earl...
Isn't it enough? Working with fractions to me .........
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Helder Ferreira from Setúbal, Portugal, (Europe)

12-21-2009, 08:56 PM   #19
dieselpilot

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Re: Trying out metric

Yes, metric leadscrews and dials on the ways and a metric threading lead screw. I work in inches while turning parts no problem, but threading is not so simple. I have to come up with some change gears. I do have a small CNC mill and just received a thread mill. I'm going to try thread milling in the mill.

12-22-2009, 03:45 AM   #20
Deanofid

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Re: Trying out metric

Quote:
 Originally Posted by mklotz Do you still use that hundredweight (cwt) that weighs 112 pounds?
Talk about getting your moneys' worth. 'Course, that would make me even fatter than I already am..

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