RE: [gingery_machines] Re: new article: How Accurate is Your Micrometer?

 

From the chart it appears that a regular  20" gage block that is measured at 78 degrees F instead of 68 degrees F it would be .0001" longer.  That's not much.
Jim
 
 
--- On Tue, 1/25/11, Rick Sparber <rgsparber@aol.com> wrote:

From: Rick Sparber <rgsparber@aol.com>
Subject: RE: [gingery_machines] Re: new article: How Accurate is Your Micrometer?
To: gingery_machines@yahoogroups.com
Date: Tuesday, January 25, 2011, 5:51 AM

 

Shannon,

Clearly Mr. Johansson didn't live in Phoenix in the summer ;-))

If the gage blocks have a known temperature coefficient, they should be usable at any temperature. Just apply the correction factor.

I just did a little poking around and found

<http://www.mitutoyo.co.jp/eng/support/service/catalog/09/E4334.pdf>

It says there is an uncertainty in the coefficient of thermal expansion. So that is why you want to stay with 20C where this uncertainty is zero.

Rick

-----Original Message-----
From: gingery_machines@yahoogroups.com [mailto:gingery_machines@yahoogroups.com] On Behalf Of Shannon DeWolfe
Sent: Monday, January 24, 2011 9:51 PM
To: gingery_machines@yahoogroups.com
Subject: Re: [gingery_machines] Re: new article: How Accurate is Your Micrometer?

Rick,

I don't know anything about anything. But I read that Mr. Johansson
settled upon 20º C (68º F) to dimension his blocks because that is the
most likely average temperature in a shop. Quite a practical man, Mr.
Johansson.

Regards,

Mr. Shannon DeWolfe

[Non-text portions of this message have been removed]

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