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Zeroing old Brown & Sharpe micrometer

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Djl338

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I have my grandfathers Micrometer, it’s in excellent condition, except I don’t know how to zero the piece. it’s unlike any of my other micrometers. I got it to go to zero, below the actual “0”, by loosening and tightening the cap, Maybe it’s supposed to zero below zero? it’s a 1-2” micrometer . Can’t find much on the web, thanks for the help
David



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Boswell

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so, have you used a gauge block to see if it needs calibration? It might be just fine the way it is.
 

benmychree

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There should have been a 1" diameter disc about 1/4" thick with a hole in the middle to set the mike; it looks like you have it set at less than 1", but that is the method to set it; look on e bay for the setting standard if you do not have one.
 
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Djl338

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Tried with the Mitutoyo calibration block, and it’s off.
No, unfortunately no calibrating disc,. I’ll check eBay. Then, would it be a matter of loosening the cap, holding the thimble,setting it and hopefully getting the correct zero? Does the spindle fit through the hole in the disc? I have more modern micrometers, just thought it would be cool to use Grandpa’s tool he used the 40’s
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macardoso

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It looks like the back cap might unscrew with a pin wrench to expose an adjustment cap. I have a mic that adjusts in a similar manner. That standard should be sufficient for setting the micrometer. It is beautiful, especially for something from the 40's.
 

Boswell

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I think it depends on how accurate you want it to be. Low accuracy would be to just be sure the faces are all very clean and then do as you say above. move the barrel until it reads what the known distance is telling you. Higher accuracy would be to take to shop that can set it traceable to a standard in a setting controlled for temperature and possibly more.
 

macardoso

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Djl338

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Thanks guys, found the calibration disc on eBay, (amazing). If I remove the cap the thimble loosens, I think it’s a taper fit? But it does allow for some adjustment, by tightening In that article.when I read down does have a description, thanks. I guess I really don’t need a .00001 tool, but would like to get it to a close standard. The thing about it, just feels so nice, well-made and smooth to operate,
Appreciate the help
David
 

benmychree

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I think that the spindle has a large diameter end that is trapped between the thimble and the threaded cap, which when loosened should be able to be reset to zero, then re tightened; when you have the gage in place and snug, lock the spindle lock so you can rotate the thimble to zero. Do you have the adjusting pin spanner wrench?
 

Djl338

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Thanks, I’ll give it a shot, the disc should be here the end of the week
 

mmcmdl

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You really didn't need to purchase the disc , the Mit rod would work fine . Nice mics , I have a few ……………………...dozen . :big grin:
 

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Djl338

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Yes, figured that but for $10.00 I’ll have the original complete set (I have the original wrench). Wow, few dozen? Vintage pieces or just in general?
Still can’t get the adjustment to stay on or above the zero, is there something to adjust under the cap?
 

Diecutter

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On my Brown & Sharpe 3" mike the barrel is unscrewed completely, which allows access to the adjustment sleeve, which is tweaked with the wrench (the one shown is for a Starrett, but you get the idea) . Maybe your mike adjusts the same.. See photos. Mine is already dead on zero, so I didn't play with it. Hope this helps.287588287590
 

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Djl338

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Thanks, when I take the cap off there is a nut that looks like the little Spanner wrench that was in the box fits on, I’ll play with it, thanks for the photos
 
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