Thanks for the replies. I think I’ll press ahead under my own steam.
However:-
Mr Stevenson, Sir, you are a Gentleman. Your drawing will save me measuring up and drawing it myself. What’s more, it’s not the first time this has happened. A week ago I googled “ER collet chuck” and your drawing for one of those surfaced, from which I turned one for my Myford. Appreciation where it’s due, and I’d like to thank you for taking the time and trouble to make this information available for the greater good. Well, for my good at least. Where do I send the royalty cheque?
Pete