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Machine Shop and Tool Talk

Micrometer Re-Cal


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  #1  
Old 12-27-2013, 09:44:25 PM
jdam904 jdam904 is offline
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Default Micrometer Re-Cal

Is there any one in Florida I could send my micrometer for re-calibration? I wanna be sure it's in calibration before use. It's a 1".
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Old 12-27-2013, 10:07:40 PM
ronm ronm is offline
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Default Re: Micrometer Re-Cal

Quote:
Originally Posted by jdam904 View Post
Is there any one in Florida I could send my micrometer for re-calibration? I wanna be sure it's in calibration before use. It's a 1".
What kind of mike is it? A 1" mike is easy to tell if it's in calibration, just close it & it should read 0. No need for a standard pin or gauge block. All micrometers have a means of setting zero, I have Central brand that use an allen screw, a little allen wrench comes with the set. You unscrew the cap from the thimble & the screw is exposed. Loosen it & set zero, then tighten it back...If it has the friction thimble, set it with that, & always use it, & the reading will be consistent.
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Old 12-28-2013, 03:35:25 AM
beezerbill beezerbill is offline
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Default Re: Micrometer Re-Cal

What make is it, and how old is it? A high quality micrometer that has not been abused can be "calibrated" as ronm states in the previous post. If there is a chance it is worn that can be checked using gauge pins. A simpler way to check its reading throughout its range is to compare it to a high quality micrometer, such as a Starrett or Mitutoyo that has a known history and has not been abused. A good thing to use as a go between from your micrometer and the "known good one" are the shank end of a set of drill bits.
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Old 12-28-2013, 09:20:38 AM
I like oldstuff I like oldstuff is offline
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Default Re: Micrometer Re-Cal

Just click on ebay or Craigslist and pick up a micrometer standard for your use then you'll have it forever.

A 1 inch standard will do a 2 inch mic. As said for the 1 inch, you just close it to check it. Or you can check it with the 1 inch standard.
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Old 12-28-2013, 10:47:31 AM
SparkyMil SparkyMil is offline
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Default Re: Micrometer Re-Cal

The mics should be checked at 0, 1/2, 1 inch with known gage blocks, it is possible to be right at one end of range and off at the other. Jim
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Old 12-28-2013, 01:50:45 PM
pjjms pjjms is offline
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Default Re: Micrometer Re-Cal

What causes them to be correct at one end and off at the other?
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Old 12-28-2013, 04:03:04 PM
SparkyMil SparkyMil is offline
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Default Re: Micrometer Re-Cal

Alot of use at one end or the other makes the threads wear more in that spot and incorrect readings, probably only be a few tenths, but when doing precision grinding with 3 or 4 tenths tolerance, it could cause problems. dropped mics can also cause the problem of being right on one end or the other. Jim
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Old 12-28-2013, 05:18:27 PM
ihredo4 ihredo4 is offline
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Default Re: Micrometer Re-Cal

I was always taught to check them in 3 places and then 3 different places on the next calibration.
IE 0, .500, 1.0 then next .250, .445, .768 then .333, .666, .999 etc.
I finally got to the point that if I was checking a tolerance zone of .434- .441 I would check the mike at both of the numbers just to make sure.

As for the OP check with a local machine shop and find out where they send their mic's at. The have to have them calibrated somewhere and they would know where the send theirs.
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Old 12-28-2013, 05:58:07 PM
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OTTO-Sawyer OTTO-Sawyer is offline
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Default Re: Micrometer Re-Cal

If you're lucky enough to know someone that works in a factory and time it right, you might be able to sneak yours in and get it checked for free while they're calibrating a batch of them.

They will want some kind of identification on it though. Some places use small stickers for ID tags and some require them to be engraved.

I've worn out a couple mic's and several calipers from checking parts 100% at certain diameters. The mic's would still zero out and check OK at several locations, but still be off where I needed them. In a pinch, I would get a pin gage and set my mic to it at the diameter needed (rather than wear out yet another mic) , but that throws it off for all other readings so don't use it or let anyone else use it for other dimensions.
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Old 12-30-2013, 11:40:00 PM
Richard W. Richard W. is offline
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Default Re: Micrometer Re-Cal

I would get a set of gage blocks. Then you could check any size you desired though out the micrometers range. Just clean and stack the blocks to the desired size.

http://www.ebay.com/itm/Precision-Ga...#ht_1923wt_981

Richard W.
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