Metric Micrometer: Percussive Adjustment

This metric micrometer has resided in my tool chest just short of forever:

During that entire time, it read 0.025 mm too high: when the spindle was on the anvil, as shown, the thimble sat 2-½ divisions above the index line. Not off by much, but an annoying bit of mental arithmetic every time.

It doesn’t get a lot of use, because I rarely need more precision / accuracy than my digital calipers provide, but measuring those teeny USB wire strands finally forced me to adjust the poor thing.

A cap unscrews from the end of the thimble, revealing the setscrew locking the thimble to the spindle:

Unfortunately, loosening the setscrew (with a 2 mm hex wrench) didn’t release the thimble:

After steeping the joint in Kroil penetrating oil for while, I stood the thimble on the bench block and gently tapped the spindle with a punch, just enough to break it free:

Then it was a matter of screwing the thimble back onto the frame until the spindle contacted the anvil, continuing to screw the thimble until the 0 line matched the index line, and tightening the setscrew. There was some slippage as the Kroil worked its way further into the joint, but a firm grip on both got the job done.

That should hold it for the rest of forever.

Speaking of forever, the 3D printed repair part for my caliper is now fifteen years old:

I’ve been doing this for quite a while …