Dial Bore Gage Specs

So I got my ring gages. I also brought everything in the house to bring the part temps up to 70 degrees.

Please check my math and reasoning
I got a 45mm XX Edmunds gage = 1.7716"
Set the Dial bore to 0 with the ring Gage. Measured the rod bearing size got .0022 larger (yes I had to interpolate the .0002) so the bearing bore 1.7716+.0022= 1.7738'
Crank measured 1.7708

Clearance 1.7738-1.7708=.003 clearance
 
So I got my ring gages. I also brought everything in the house to bring the part temps up to 70 degrees.

Please check my math and reasoning
I got a 45mm XX Edmunds gage = 1.7716"
Set the Dial bore to 0 with the ring Gage. Measured the rod bearing size got .0022 larger (yes I had to interpolate the .0002) so the bearing bore 1.7716+.0022= 1.7738'
Crank measured 1.7708

Clearance 1.7738-1.7708=.003 clearance

Your math looks correct.
 
Set a micrometer with blocks, ring gauges are far easier to use however you will need thousands of them to cover the bore gauge range in tenths.
 
Actually there is no special holder needed, set micrometer with blocks, a mic stand is nice but a vice works fine I often use large toolpost blocks for this. Set bore gauge and have at it.

What is a "dial gauge holder"?
 
There is a small but important caveat to setting a bore gage with either a micrometer or gage blocks, or any flat surface method. Bore gages have, in general, some mechanism to center themselves in the bore. There are a few different way this is accomplished, but with wear, they often fail to do a perfect job of centering the measuring contacts. The result is that the measuring contacts, which should touch the bore only at the true diameter line, geometrically described as a straight line across the bore that contains the center point of the bore, are pushed off to one side, off the diameter line, resulting in a false reading. It will always read smaller than the actual bore size because of this. That's the main reason gage rings are superior to any other means of setting bore gage. Just something to bear in mind.
 
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