T140V

And it is exactly this that led to my confusion. I had seen the Tracksetta 18" listed as 2nd Radius, 21" as 3rd radius, and so on. But now I know they are actually different, it was matter of minutes to draw up the necessary templates to use in Inkscape to do the track plan.

Thanks all. I had naively assumed that a 2nd or 3rd radius curve would have a standard dimension, but now that I know I can plan accordingly. As a Mac user, I'm using Rail Modeller Pro for track design which is ok but has some glaring issues when it comes to design (like you can't define a Tracksetta 21" radius curve for example) - so much so that I've started using Inkscape for some aspects of the design. Because of the physical constraints of the location I'm going for Set Track in a couple of places and will be down to 2nd radius for a couple of turns. Not too worried as I'm modelling a rural branch line so no big stuff.

Returning to the hobby after a break of just over half a century and blimey, things have moved on a bit haven't they? I'm currently designing my layout and TBF I'm a bit confused as to how curve radii are actually measured. Take 3rd Radius curves as an example. A standard piece of Peco Settrack 3rd radius is described as being 505mm / 19.75", but a 3rd Radius Tracksetta template is listed as having a radius of 21". Does this mean that the two curve radii are actually different, or is it just a question of what is actually being measured? I had assumed that it would be correct to measure the radius at the centre line of the track. My worry is that I was hoping to use set track sections in some places and then use flex track in others, but if the radii are actually different it's going to complicate my track planning somewhat. Many thanks for any and all enlightenment.