Ok wow that was quick Brian

Can I make a donation for your time and effort ?

Possible improvements to the control the output

A) The spiral lines increase in distance apart smoothly, which is spot on :-) but can we control this increasing % in any uniform way ?

B) Also would it be possible to control the inner starting radius or diameter ?

The a & b values control in the script ? the size of spiral produced using the script seems to be about 25mm / 30mm - can this be increased if the maths allows or do I just need to scale up ?

atan - ? not sure what this refers to ?

This in effect will become the artist perfect set of french curves in MOI if you can devise a way to control A & B above

best wishes

Andy