EtV wrote, QUOTE: *Beware! Pre-metrication, electrical socket boxes were often 4BA, which is very close to M3.5 ..... UNQUOTE:
Thanks for that Eric, I thought all electrical stuff was 4 & 6 BA (isn't that why BA was 1st invented?) but have had to do little or no electrical socket, etc, stuff since I've been here, so wasn't aware of the difference. Thanks for the tip, 'cos looking at some of my Swiss electrical bits & pieces it does look just like 4BA, and I'm sure I would have pressed on with BA.
But as it happened I got lucky. A good local tool shop where I go from time to time was having a clear out of old stock and was about to throw some rather good-looking hand and machine taps & dies away. When I protested I was allowed to take the box home and sort through what I wanted (which was quite a lot actually!) and take the rest back, paying "what you think is fair" for the stuff I'd kept. I put 50 Swiss Francs into their coffee fund (about 35 quid at the time) which made them more than happy, and I ended up with a "collection" of all sorts of stuff, including a lot of Metric Fine taps & dies, & including several 3.5 taps & dies. No idea why they were throwing the stuff out, but I was sure pleased, and all the stuff I got was good quality local Swiss & German manufacturers.
But I STILL start off with my cheapo Aldi Metric set!
Re your earlier comment about your stuff "in their boxes". OK if they're individual cardboard or plastic boxes, but if loose, and simply protected with that "dipped into brown waxy stuff", which doesn't last very long before it all splits, a good tip is to go to your local car/aero model shop where they sell neoprene and silicon tubing in various IDs. It's for model engine fuel line, sold by the metre, but cut to short lengths makes excellent tap protectors.
Re starting a male thread (using a die), yes, it's a bugger that, I sympathise. I only use a lathe for that now (run by hand or VERY slow motor) but always had trouble before I got the lathe. About the only thing I can suggest without a lathe is to make a very exaggerated taper at the start of the rod to be threaded (file it in the pillar drill so it's pretty symmetrical) and then after the thread is cut, saw the offending taper off (assuming you have the necessary extra length to start off with).
HTH
AES
P.S. @phil p: Good tip that, a bit of lubricant when doing any sort of metal cutting never does any harm and is usually a positive help. I do much the same (except it's a little tin of 3 in 1 or similar).