Radius gauge and reverse engineering

[tonyfoale]

Tony,
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

I found the typo in the indicator reading section. I wrote 49.97 which should have been 4.97.
I can't find the error in the probe spacing part.

[owen moore]

There is a similar gauge used in optics. I think it is called a diopter gauge and it is used to measure the curvature of a lens or a mirror. Nice tool, Tony!

[volodar]

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, a typo in the pdf´s Appendix:

¨Firstly we calculate the slope of the two lines AB and BC, then we bisect lines AB and BC with normal lines (shown in red), these will meet at the centre. The slopes of these two lines are obtained by multiplying the slopes of AB and BC by -1¨.

This holds true only for slopes of 1 or -1. Perpendicular lines have slopes that are negative reciprocals of each other.

In the diagram, by inspection, line segment AB has slope of about one half. AB´s red perpendicular bisector has slope about -2.

[tonyfoale]

Tony, a typo in the pdf´s Appendix:

¨Firstly we calculate the slope of the two lines AB and BC, then we bisect lines AB and BC with normal lines (shown in red), these will meet at the centre. The slopes of these two lines are obtained by multiplying the slopes of AB and BC by -1¨.

This holds true only for slopes of 1 or -1. Perpendicular lines have slopes that are negative reciprocals of each other.

Of course, you are correct. That was a stupid mistake.

PS. File has been fixed.