As some might know I am not an expert modeler, although I have just got out again a double-oval track I made a few years back. I have been amazed over the last three weekends that my kids (11 & 6) have switched off the telly and watched some authentically very dubious trains going round-and round- and round for
hours. (e.g. GWR pannier tanks pulling LMS express passenger coaches with half a dozen Southern Railway vans on the back

...........could it be turning into the S&D perhaps?
Anyway, I am looking at some minor track modifications and want some geometry. I know I could just wait for the bits when they arrive in the post, but I want to do some technical drawings, to get tangents and transition spirals. ( I'll leave out the superelevation calcs for now !) I've tried Hornby website - but no good. I dont want to buy a manual or a computer programme just for this.
Right then. Here's the maths homework...........There is a Hornby standard curved point which both legs appear to be 2nd radius. i.e arcs of two circles of radius 438mm. The
centre of each of these circles will be at a different position. How far apart are the centres? 67mm perhaps?????