Micrometer calibration adjustment

[Technical Ted]

Can you rotate the sleeve (the barrel in your diagram) to calibrate? It may be just a friction fit and allow you to rotate it to zero it.

Good luck,
Ted

 

[pdentrem]

Here a page showing various makers. May be a help.

How to Adjust an Older Micrometer

How to Adjust an Older Micrometer: When you acquire an older micrometer, like an early 20th century Brown and Sharpe, you may find that it does not properly zero. After cleaning the measuring faces, twice, it still won't zero. It is pretty close, but not quite. The spindle turns free…

www.instructables.com

 

[clueless]

It may be left-hand threads.

Thanks, I wondered the same so I tried it both directions - no movement. But I will try the other micrometers to see if anything moves.

 

[clueless]

Can you rotate the sleeve (the barrel in your diagram) to calibrate? It may be just a friction fit and allow you to rotate it to zero it.

Thanks, I did try that. I applied as much force as I thought necessary (in both directions), with no movement. Maybe it just needs more force but I'd prefer to explore all other possibilities before attempting that. Honestly it isn't worth ruining them, I could just compensate my measurements by the amount they are off if nothing else works.

 

[clueless]

Here a page showing various makers.

Thanks. I saw that page while researching this. Unfortunately it did not have any information regarding these particular micrometers or anything like them. I'm now of the opinion these were not big sellers (I've found absolutely no mention of them on the web). It could be quite possible they did not sell because they are not adjustable??

 

[keeena]

Watching this thread - was about to post the same question as Clueless. I have an old B&S #59 which has the same adjustment type as yours. My spindle appears seized to the thimble. Pic below. @clueless: interested to hear what ends up working for you.

I'm going to start soaking the spindle/thimble assembly in penetrant for a few days, then maybe try an ultrasonic cleaner.

 

[RobertB]

Can you unscrew the base part of the ratchet screw from the end of the thimble?

 

[clueless]

Can you unscrew the base part of the ratchet screw from the end of the thimble?

I believe this is what "RJSakowski" was saying previously when he posted this - "I suspect that the two knurled sections on the barrel unscrew to reveal the adjustment."

Something like "keena" shows with his B&S (I've added an arrow):



As far as I can tell the thimble and ratchet mount are one piece on mine. I was not able to separate them and I do not see a 'line' that indicates they are two parts. I suppose it's possible this actually is two pieces that are machined in a way that makes them appear as one part, and they are corroded/frozen together. If I don't have any better luck with the other micrometers then I can give it another try, just like with separating the spindle from the barrel.

 

[clueless]

I'm going to start soaking the spindle/thimble assembly in penetrant for a few days, then maybe try an ultrasonic cleaner.

Thanks for your picture. As I stated in my last post I do not think mine is exactly the same, but it helps to see the parts separated on yours for reference.
I tried some penetrant lube but no help. I am not suspecting there is corrosion internally on mine, judging by the rather clean exterior. These appear to have been well stored in the protective case with no signs of rust or oxidation (they spent their lives in a desert climate). But anything is possible and a good soak and ultrasound cleaning is worth trying. Hopefully after Christmas I'll have more time to try some of the suggestions offered throughout this thread.

 

[RobertB]

I was referring to this piece possibly unscrewing from the thimble: