According to John Martin :
[ ... ]
There is that. I guess that I was just assuming. :-)
As am I. (Well ... I do have three lathes without reversing switches -- but they are the small ones, the Unimat SL-1000, the Taig (though I am going to be switching in a small three-phase motor and VFD which will give it reversiblity), and the Emco-Maier Compact-5/CNC, which would have no problems with the chuck coming off under power, because the chucks mount to the flat nose of the spindle by three or four screws which pass through the body of the chuck. But I'm not sure how well the CNC could be adapted to reverse running of the DC motor. I've been more tempted to use some of the extra control outputs to switch between two speed control pots in place of the single one which is fitted as it comes from the factory.
Which is why I am very glad to have the Compact-5/CNC, since all it requires is rotating a switch to go between metric and imperial threads (and everything else). So -- so far - it is what I use when I need a metric thread, though I do have the transpose gears set for my
12x24" Clausing. So far, I have not had a project which needed metric threads large enough to require that machine.Enjoy, DoN.