Quote Originally Posted by tonyfoale View Post
I have just enhanced the software to allow calculation of the curve radius and centre coordinates when the XY coordinates of three points on a curve are known.
This is useful if you use the DRO on a milling machine to determine the coordinates of three points. This does not need the radius gauge described above.
The link to the software is the same as that in the PDF RadiusGauge.pdf
Tony,

I always read your articles with interest. As I had not used my brain over Christmas, I decided to work out the formula for the radius before reading the appendix.
I ended up with a different and, perhaps, a simpler formula: R=(s^2 + h^2) / 2*h
(where s is half the distance between the probes, h is the value on the indicator and, ^2 means 'squared')

I hope you won't mind if I also note that there are some typos in the pdf file : in the sections were you discuss errors in the indicator reading and errors in measuring the probe spacing, the radius value are not correct.

Regards,
Paul