Once had a set of tee shaped thingos for getting internal measurements, the cross section was spring loaded and once you put it inside object you twisted handle so it locked and then you could measure with mike. Can't remember name of tool to enter into google or ebay.
Telescopic bore gauge.
Thanks.:)
I've never had much luck with cheapish versions of these -- could never get consistent measurements, and one started to not lock after a short while. Very frustrating.
I bought an inside micrometer from Chronos £29.95, excellent results, and I expect it to last a lifetime. This and another micrometer the next size up ( 1" - 2" ) covers 99% of my bore measuring, All the best, Peter W.
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