Posted by Mike Bondarczuk on 19/04/2017 10:49:50:
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but do agree that I cannot think of any reason why the chuck should turn backwards, so to speak, as patron g off is very easy and safe and threading is straightforward with the proprietary Hardinge system.
Mike
Mike's comment left me wondering "why is reverse needed at all" so I did a search. Practical Machinist has a surprisingly long list, including:
Quicker not to disengage half-nuts when cutting short threads; parting-off; grooving; boring in difficult materials such as bronze; cutting some metric threads; many internal operations; tool-post grinding; chamfering; winding springs; making matched inside and outside tapers; right-hand internal threading; tapping (or rather removing the tap under power); quick stop (not all lathes); and my favourite "unwinding a trapped shirt-sleeve".
One good point made about internal turning is that it's easier to see what you're doing with the lathe in reverse and an upside down tool . Also, running in reverse, it's possible to work out from an internal shoulder.
Dave