Simple/Manual Centre Finder

Hello all,

I'm a basic user of LCNC - I know it reasonably well, but don't use a tool changer, only have a basic through tool Z probe which gets occasional use - you get the idea: my set-up is pretty rudimentary but I get good results and productive use out of the software.

When I need to find the centre of a circular feature I've been touching a dowel off at three points around a circumference (fag paper or multimeter method) and feeding three sets of X,Y coordinates into a spreadsheet which then works out the centre for me, like so:





Here's the sheet in OpenOffice format.

It works, but I was wondering if there was a way to incorporate a simple centre finder tab into the interface, something that would look a little like this:

 

The first three buttons to touch off the three positions on the circumference and the 'FIND CENTRE' button to perform four ops:

Calculate the X,Y centre coordinates
Lift the Z axis to its G53 0
Move to the calculated X,Y centre
Set G54 (or current WCS) X,Y to 0,0

So I guess there would need to be six variables that get written using date from 'current position' numbered parameters #5420 & #5421

POSA_X
POSA_Y
POSB_X
POSB_Y
POSC_X
POSC_Y

And then the two calculated variables that are used in a subroutine to lift and move the spindle to the centre and zero out X,Y at the new position

CNTR_X
CNTR_Y

I get that this is still clunkier than using a probe, but I honestly have little need for one!  If I have to keep punching the numbers into the spreadsheet then that's fine, but to have this in a tab would be cool.  Am I thinking about this in the right way?

How would you tackle it?

Many thanks.

Wal.

I used your formulas for calculating the center of a circle and created a widget for qtdragon that does it.
(There's also a Python function that calculates the center from three coordinates.)
You're using axis, so it probably won't be useful to you.