Finding Center Location

[toododd]

My company uses a spherometer type gage to locate the center location of hemisphere (cavity) relative to the surface that it is machined into. The gage uses a master of known value and this formula. Equator Location = Gage Reading + .707 ( the change in diameter difference from nominal). I am trying to figure out where the .707 came from. We are trying to reverse egineer the gage. One document we came across calls it "angular constant". Does anyone know where the .707 came from?

 

[mloew]

toododd,

Might it relate to ~0.5((2)^1/2) (i.e. half of the square root of two)?

Best regards,

Matthew Ian Loew

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[smah]

How about sin(45°)

 

[SteveAG]

Sin 45° = (2^1/2)/2 = .5(2^1/2)