Re: [ATM] Spherometer calibration, precision, etc.

[Richard <cnc@cncservo.co.uk>]

Hi Mike,

Monday, February 26, 2007, 4:59:17 PM, you wrote:

ML> My spherometer bases are certainly not perfect, so I calculate the 
ML> effective radius of the balls based on measurements of know mirrors (I
ML> have plenty lying around).

Sounds a good first order approximation Mike, but how well does the
formula hold up as the balls diverge from an equilateral triangle?. I
wonder if it would be better to take three micrometer readings across
3 pairs of balls and plug the whole lot into a spreadsheet, for
critical work at least. You'd need another couple of readings to
locate the gauge head I guess.

Did you ever find a cheapish source for Ruby balls Mike?

-- 

Best regards,
  Richard in the UK

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