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### Author Topic: find a circle centre and radius from three points on a arc - How?  (Read 2148 times)

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#### zhitomirjohn

• 1
##### find a circle centre and radius from three points on a arc - How?
« on: May 10, 2007, 08:30:47 AM »
Wizards now seem to be appearing that will find the centre and radius of a circle from three points on a arc.  Can anyone help with the maths for this so that I can create the appropriate G code.

Is it possible to produce a modified centre finder in the shape of a sword, whereby the tips of the handles touch the arc at a fixed distance apart and the top of the handle slides to touch the arc. A datum line at centre of the sword then gives a reading of the radius and hence you have the centre and radius.  A depth micrometer could possibly be modified.  I do need the maths to try this though as I presume that the scale will be non-linear.
John

#### Brian Barker

• 3,864
##### Re: find a circle centre and radius from three points on a arc - How?
« Reply #1 on: May 11, 2007, 12:03:42 AM »
John,
look on the web for 3 Point Arc and you should find what you are looking for.

Thanks
Brian
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