Three point internal micrometer (holtest) for bearing clearances

Hello has anyone used or have an opinion on these type of micrometers for checking bearing clearances, it bothers me the marks an internal bore gauge leaves behind, and these seem to have a larger contact surface which would have less surface pressure on the Babbitt.

whats your thoughts?

cheers

Andrew

I haven't used one myself. The marks that the bore gauge leaves can easily be polished off the bearing surface as described in the course. One aspect to keep in mind with a device that makes contact in three places is that there is some level of eccentricity to the bearing shells. What we are interested in is the measurement vertically for example in the main bearing tunnel. If we actually measure the clearance in line with the parting line of the cap we will get a larger measurement due to the eccentricity. This may throw off the reading you're going to get with the tool you've mentioned.