Setting an internal micrometer

[John MCParticipant @johnmc39344]

I have a Fowler-Bowers internal micrometer, 0.50" to 0.62" range, the type with 3 expanding pins. While it is accurate to the various setting rings I have, the scale on the thimble does not quite line up with the scale on the sleeve, if that makes sense, enough to cause a reading error unless I am careful.

On an external micrometer this type of error can usually be corrected by moving the sleeve axially with a tiny C spanner.

I've looked at the manufacturers website, it explains resetting the thimble to a gauge but not resetting the sleeve.

Its bound to catch me out one day so I would like to reset the sleeve,anyone know how?

John

[John MCParticipant @johnmc39344]

[ronan walshParticipant @ronanwalsh98054]

Can you not send it back to the manufacturer for calibration ? Might be the easiest way to do it.

[vintagengineerParticipant @vintagengineer]

I will have a look at mine tomorrow. Have you tried unscrewing the the thimble? I think there is an adjustable ring under the thimble.

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