A note first - I've not actually used this feature - or indeed this lathe - I bought it a couple of years ago, but a couple of job changes and a house move half way across the country have meant that I've not used it - I've only really started to look at rehabilitating it from the horribly dirty state it was when I got it. So please excuse the mess. Phew - now that's out of the way...
The arrangement is actually quite simple - there's a stop that clamps to the bed, much in the manner of the auto-feed clutch knock-off on a Boxford lathe, which then activates a cranked rod with a piece of rack gear welded to the other end.
This turns a gear that's attached to the half nut activating shaft, and the half nuts open at the appropriate time. Part of the rear casting of the apron is removed to make space for the activating rod.
I've attached a few pictures below that should make this a little clearer. The rack is the same pitch, it appears, as that along the front of the bed.
One immediate observation I have is that the precision of the stop may perhaps not be too good, as the half-nuts will only open 'as fast' as the rod is pushed in by the stop - some biased-open over-centre arrangement would have been better.
On that subject, has anyone though of - or even better actually made - the dog-clutch threading reverse attachment serialised in ME (or MEW perhaps) for Boxfords and some other machines for a Viceroy ?
Any measurements anyone would like me to make of these bits, now's the time !
Youra.
