In article ,
Henry Kratt wrote:

[ ... ]

I use an older HP 11C Scientific, among some other vintage HP's and keep
it in a one quart clear plastic zip lock bag that I replace frequently.
Fold the bag round back and tape it. The reason for the affinity for HP
is that I like RPN and the calculator carries 12 places of accuracy,
whether you can see it on the readout or not.

If I want to lay out 127 divisions around a circle, each step is 2.83
degrees, but calculator will carry 2.83464566929 degrees to be added to
the 2.83 degrees. This very accurate number allows the error to be
distributed around the circle as best as you can read your dial.

And -- with the 15C at least, you can enter a radius and the
angle, and it will convert it from polar to rectangular notation, so you
can crank in X and Y coordinates on the mill prior to drilling the
holes, so you can do it without a rotary table, if you need to do things
that way.

Enjoy,
DoN.

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--- Black Holes are where God is dividing by zero ---