Thank you for the encouragement, chaps. It's not even easy to log in to this forum at times, nor to post anything once here thanks to that 'Captcha' thing being almost illegible!
Murray Dickinson has hit the nail on the head. Given we all know the basics of engineering drawing as such, his analogy with driving is good in that you need to learn to drive then become familiar with the quirks of the particular make and model you buy.
The problem I see is that TC (and other packages I've sampled) assumes that we all know the basics of CAD software before we even touch any given CAD package. Finding that information is a nightmare, I suspect because as computers become ever more ubiquitous, software publishers become ever more sure "we all" know the principles just as the motorist looking for a new car already knows how to drive.
With the greatest respect, a forum like this is something of a deterrent too, because a quick glance down its questions reveal they are predominantly about the most obscure items; some apparently on topics closer to operating-systems and file-handling than drawing things. if you struggle to so much as draw two lines on the screen you feel totally out of place among all that display of PhD-level skill and experience.
OK, how about the training videos?
Well, when I bought TC complete with an alleged training video on a separate disc. I followed the instructions very carefully only to find that after a few iterations of the same command the requested ESC key had changed its function from completing the given move, to deleting the whole drawing so far! This happened every time I tried so it was not a one-off miss-key on my part. "Paul The Cad" (a UK agent) kindly sent me a video he'd produced himself but to me it was just someone demonstrating what TurboCAD does, rather than how to make it do it.
The on-line videos from the Help menu... they rely on Adobe Flash Player, which must be least useful and most unreliable software published, because it does not load fully, let alone run, and offers no help or support whatsoever!
TC's on-line pdf manual is merely a list of TC functions, an aide-memoire for your experienced people. It doesn't tell you how to use each function, assuming you can find it in the book in the first place, only what it does, and then rather vaguely. Certainly doesn't help you understand CAD principles because its authors assume you know them.
I gave up for some time, then found a book: CAD For Model Engineers, by D.A.G. Brown (A British model-engineer), in publisher Special Interest Model Books' 'Workshop Practice' series. It's slightly off-putting thanks to the evident age of the author's own computer in the cover photo - 5" as well as 3.5" floppy drives! Nevertheless I thought it might explain the basics, such as Layers.
So I tried again, yesterday. A heroic 2 or 3 hour battle produced a single view of a rectangle with a notch and two holes. (To draw the outline break across the notch I over-printed that part of the rectangle with a white line, there being no obvious alternative.) Dimensions too, once I'd twigged that some of the menu choices didn't work, and the only one that did would not work consistently, and kept covering the screen with pink lines and crosses to no obvious purpose!
I could have sketched the thing on an envelope and half-made it in that time. Could not even determine how to copy a line or circle - nothing seems to work more than once or twice in the same way, and when I did manage to copy and paste anything I had no idea how I'd done it. It seemed entirely random. The intuitive ways - Select original, Edit>Copy, Select destination, Edit>Paste, or Select and Drag, as with most Windows software - do not seem to work in TurboCAD.
It was suggested I buy tuition but I can't afford that, especially with no guarantee that I would make any sensible progress. So I will probably stagger on a little while longer, trying it now and then when in the mood, but in time will have to decide if it's worth wasting hours and electricity on it. Just as you need formal driving tuition even before you buy the car, CAD is intended for learning in formal courses, not at home, hence the lack of any real literature to help the beginner.
In his book, David Brown says he was able to sell his drawing-board. I'm glad I have kept mine.
Now let's see how illegible Captcha is, this time...
No it wasn't. Try again! It's crap!