My layout track planning is based where possible on what we have rather than what we need.

In K track days I would know that 4 x 2232 would be a perfect substitute for 3 x 2231. for a 90 degree R2 curve

So now having moved on the new extension sections being C track I needed to have a 180 degree curve of R2 so normally 6 x 24230. But I had not enough 24230 but a surplus of 24224 so my little brain assumed that 5x 24224 plus 2x 24230 would equal the 180 degrees but Mr SCARM would not agree. Of course when you look at the detail a 24224 is actually 24.3 degrees not simply 24 so Mr SCARM is right. I did not try it in practice to see if the c track "give" would allow it as this to me weakens the track and spoils the geometry.

As an annoying boss of mine used to say regularly "If you assume you will make an ass of you and me".

An then my wife asked a really stupid question - "Is your train layout nearly complete?" - you would have thought she would have worked out after 30 years there is no such thing as finished in MRR.

Hello Rwill!

It's just a matter of math... your solution gives you 181,5 degrees, instead of 180.

Of course, sometimes some degrees minus or plus does not really matters... just move the rails some centimeters and spoil the geometry a little bit...

Here you could have some geometry examples:

http://www.marklin.nl/support/support-pdfs/602653Baanontwerpen_Marklin_C-rail.pdf

The first example shows exactly what you described... look that you need a 24206 track together with a 24224 to have a virtual 24230...(30 degrees)
Or two 24207 that completes three 24215 for 60 degrees.

Cheers,

Walter