Michael- the drafting tool was PCB Wizard 3 which I bought from Maplin a few years ago and has managed the transition from Windows XP to Windows 7, but I now wonder if it will survive if I download Windows 10.
There was no great advantage in using this program, it was simply the only program I had available which I could get to work for this task. A decent drawing program like Turbocad would probably be much better, but I don't have that.
I had a senior moment when adding the numbers to the scale as I started at the top with zero and worked down the scale, only to then realise the scale read the wrong way round and I should have had zero at the bottom.
The scale on the friction ring was well worth the extra work and I would advise anyone making a similar dial to do this since it makes it much more versatile.
Doug