Another "What is it"

Hello all.

I recently agreed to help a friend clear his workshop.

I have come across an odd measuring tool.

It is made by Sigma and says "based on NPL design" and is obviously a measuring tool. When the end is gently pressed a needle marker moves in the window.

It may have been inserted into a sort of enormous micrometer fitting I have also found.

Picture here or if that fails on the next post!

Any ideas

Thanks

It’s exactly what you’ve assumed ... a precision indicator for the enormous micrometer.

MichaelG.

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‘ere we go :

https://collection.sciencemuseumgroup.org.uk/objects/co59510/0-2-bench-micrometer-micrometer

Edited By Michael Gilligan on 11/12/2019 13:44:36

Michael is spot on they and similar devices are or were used on many, mainly inspection grade tools and indeed precision machines, one of the Newall jig borer's I worked on used them in conjunction with a micrometer head and their roller measuring system

John

Thanks Michael & John. The link showed exactly the enormous micrometer.

Would this be intended to ensure a consistent pressure when measuring?

John

it's a fiducial indicator, used to ensure consistent readings with, most likely, micrometers used for inspection.

John

NPL refers to the National Physics Laboratory - the go to place for anything to do with measuring, based I seem to remember around Glasgow. Sigma was based in Letchworth and were a well respected instrument maker.

Edited By Oily Rag on 11/12/2019 15:16:34

NPL refers to the National Physics Laboratory - the go to place for anything to do with measuring, based I seem to remember around Glasgow.

NPL is in Teddington. The National Engineering Laboratory was / is based at East Kilbride outside Glasgow.

Nigel B

It's a fiducial indicator as explained by John. It is used with micrometers in place of an anvil to ensure a consistent reading. The mic is turned / closed until the needle reads zero and as the pressure used is always the same it does not matter who operates the device you will always get a consistent reading.

Alan.

My first posting is to comment on the number of smart cookies posting here. I will have to hang about the shadows to keep my ignorance hidden.

This may be of interest: **LINK**

http://resource.npl.co.uk/docs/science_technology/dimensional/moy-scmi/moy-scmi-82-print.pdf

A ‘variation on the theme’ but it gives us a sense of the standards to which the NPL operates.

MichaelG.

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Edit: This is the one I was looking for: 

http://resource.npl.co.uk/docs/science_technology/dimensional/moy-scmi/moy-scmi-29-print.pdf

Edited By Michael Gilligan on 11/12/2019 16:38:18