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Calibrating an Indicating Mic

TheInspector

Plastic
Joined
Mar 29, 2011
Location
Twin Cities, MN, USA
I work in the Inspection Department of a medium-sized Machine Shop. One of my duties is to make sure all the measuring tools in the shop read accurately. We calibrate most tools annually, and they usually need little or no adjustment from year to year.
This particular Micrometer, however, a 0-1" Indicating (Pressure) Mic made by VIS (Poland), was last calibrated in February of 2011, and is now somehow off by .075 inches. This is over 10 times the amount you can adjust it by simply turning the sleeve.
Is anyone familiar with these mics? Or have any idea how this could happen?
 
Like below?

On manual mics, the barrel can slip and slide up the handle. But I think you'd notice this. For smaller discrepancies, a thimble could have come loose from the spindle and rotated. But 0.075 is probably more than could be accounted for this way. The micrometer monkeys could have gotten into your mic, and the gearing on the indicator may have slipped a tooth (or three in your case, to get 0.075").
Any of these likely?

2539.gif
 
mayhaps

Yes, the indicator in question is the exact model shown below. Furthermore, I believe that mayhaps the monkeys got in and slipped the gears a few teeth, as that seems the most likely. Any clue on how to fix this?

Like below?

On manual mics, the barrel can slip and slide up the handle. But I think you'd notice this. For smaller discrepancies, a thimble could have come loose from the spindle and rotated. But 0.075 is probably more than could be accounted for this way. The micrometer monkeys could have gotten into your mic, and the gearing on the indicator may have slipped a tooth (or three in your case, to get 0.075").
Any of these likely?

2539.gif
 
You could turn the spindle to the zero position on the barrel and lock it. Then remove the cap at the anvil end. Look for an adjustment device that will bring the indicator pointer back to the zero position on the dial.

I have been inside the indicator works (under the cover plate) of Mitutoyo and Etalon indicating mikes and I will warn it is not for the unskilled in watch repair and allied fields. I got both of mine to work, but it was tricky. If there is no obvious adjustment, replace the mike or send it to a good repair shop.

Larry
 
darn, but thanks

anvil end only moves +/- .010"
I'll have to have it sent in. Thanks a bunch, guys.

You could turn the spindle to the zero position on the barrel and lock it. Then remove the cap at the anvil end. Look for an adjustment device that will bring the indicator pointer back to the zero position on the dial.

I have been inside the indicator works (under the cover plate) of Mitutoyo and Etalon indicating mikes and I will warn it is not for the unskilled in watch repair and allied fields. I got both of mine to work, but it was tricky. If there is no obvious adjustment, replace the mike or send it to a good repair shop.

Larry
 
I have an original Federal mike that yours is a copy of. Fortunately it isn't out of adjustment. You might at least want to know where the design came from.
 
indicating mic

I bought a broken federal one off ebay, and found that the needle had bent from being dropped. Carefuully tweaked at the needle with a 1" standard in the micrometer and got it to work ok. Kinda primitive, bending parts and all, but it worked out ok for me.:eek:
 








 
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