micrometer heads - assembly

On the end of the probe on my micrometer head there is a small self-retaining sleeve. Inside the sleeve is a ball and a top-hat-shaped disc. My dismantling notes have failed me again and I'm not sure if the top-hat goes between the ball and the end of the probe, or its the ball that goes between the probe and the top-hat !

There is only one small witness mark on the parts and that is a tiny brinnell mark on the large diameter end-face of the top hat.

I can see a good reason for both options. The top hat could be put outboard of the ball to prevent the gauge block from getting brinnelled. On the other hand perhaps the micrometers probe is soft and the top hat is there to protect it from brinelling.

If anyone knows the truth of the matter I would appreciate hearing it.

Gerry

Just for the record, in the event that anyone else decides to refurbish one of these machines, I have "decided" that this should be the correct assembly:-

This arrangement will provide a self-aligning contact on the gauge-block surface and thereby prevent any damage or indenting of the block. There may be initially some brinelling of the micrometer probe tip from the ball but once that's happened it wont grow further and subsequent measurements wont be affected.

Gerry

Hi Gerry what machine is that it looks like a jig borer.?

David

David, its a toolmakers measuring microscope manufactured by OMT. It is VERY robustly made so I can understand the confusion.

G.

OMT provide the measuring equipment used in Standards and Calibration Rooms, so is VERY high quality.

We used an OMT Optical dividing head to graduate the handwheel for the Leadscrew on my ML7!

My, now sadly departed, friend was in charge of Calibration!

Howard