Starrett Inside Mic is Frozen?

A

AmericanMachinist

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I acquired a number 823 inside mic set. The whole set was so pristine I didn't turn the mic barrel (mistake).

The barrel is close to mid-range (~0.020"), and I can't get it turn either direction. There's an axial screw under the back end (female end) which I also can't get loose - but didn't force.

I checked Starrett's website and didn't find a useful (detailed) parts diagram.

What am I doing wrong?

Thanks,
 
AmericanMachinist said:
I acquired a number 823 inside mic set. The whole set was so pristine I didn't turn the mic barrel (mistake).

The barrel is close to mid-range (~0.020"), and I can't get it turn either direction. There's an axial screw under the back end (female end) which I also can't get loose - but didn't force.

I checked Starrett's website and didn't find a useful (detailed) parts diagram.

What am I doing wrong?

Thanks,
Click to expand...
To see exploded parts diagrams you need to create a free account:

IMG_5371.jpeg

Starrett’s micrometer repair shop soak frozen micrometers in Marvel Mystery Oil for up to a week before trying to get them moving.
 
Thanks. I checked the download able files but what I found (even for just the head H823A/B) showed the entire head as one unit- not all the parts. Could be my error.

I'll probably soak the mic next but figured I must be missing something. There's not a spec of rust on the head that I can see.
 
I had the same issue with a 0-1" Starrett micrometer several years ago... a co-worker dropped it and it landed on the end of the thimble and 'jammed' the threads in the thimble together.

I eventually managed to get it freed up enough to turn it, but it never worked properly again.

I hope you have better luck with yours.

-Bear
 
AmericanMachinist said:
Thanks. I checked the download able files but what I found (even for just the head H823A/B) showed the entire head as one unit- not all the parts. Could be my error.

I'll probably soak the mic next but figured I must be missing something. There's not a spec of rust on the head that I can see.
Click to expand...
The downloadable files are separate from the exploded parts diagram; this is page 2 of the diagram plus the parts list:

IMG_5372.png

IMG_5373.png

For others, this is the downloadable sheet you already have:

IMG_5374.jpeg

If it’s not gummed up or corroded, it may have been dropped and the threads damaged. You can call Starrett and talk to tech support: they’re happy to help.
 
Last edited:
I sent my Starrett T236xrl mic to Precision Instrument Correction when the thimble froze. They also replaced the broken ratchet stop screw and calibrated the mic. It was worth the $100.
 
Inside mike adjusting nuts are generally set up pretty tight to avoid too easy rotation when adjusting and measuring, I'd go the Marvel Mystery Oil route and try again.
 
benmychree said:
Inside mike adjusting nuts are generally set up pretty tight to avoid too easy rotation when adjusting and measuring, I'd go the Marvel Mystery Oil route and try again.
Click to expand...
One thing you can find out from talking with Starrett is how much “oomph” may be required for disassembly. When I couldn’t get what remained of the ratchet off my 224AA find from Cabin Fever, my contact urged me to use more force than I thought was necessary (he also reminded me that as long as the thimble was carefully handled whatever I did the the ratchet couldn’t make things worse). He was right and the 224AA now is complete.
 
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