I have an old Monarch model BB lathe that has the gearbox for thread cutting, but doesn't have the acme thread or half nut. I was wondering if it would be possible to add this to the lathe. I saved it from the scrap yard and really would like to be able to cut threads. I have no idea what is on the end of the acme thread that does into the gearbox. I assume I can find a halfnut somewhere but not sure if this is doable or not. According to Monarch the lathe was ordered that way from them back in the 40's. Any help would be appreciated.
If.. Monarch shipped 'a' gearbox for surfacing-only, no leadscrew... they MAY have left-out other parts. I don't ken the 'BB' but on a 10EE, there are separate input gears and dog clutches for threading vs surfacing.
On MOST dual-use lathes there is also an interlock in the apron to prevent half-nuts and surfacing drive being engaged at the same time.
You need to check those ancillary items first.
THEN.. DIY'ing leadscrew from stock threaded material is not hard. Only expensive. Potentially costlier than the lathe has been so far.
You would also need the outboard support for the leadscrew, the half-nuts and their support and actuator bits, a thread-dial mechanism...
Not as simple as just what is in-your-face visible and obvious.
Cheaper and more universal to buy more taps and dies, tapping head, rig a die-holder to power-thread on the lathe without need of a leadscrew. Should cover 95% of typical needs, if not more... AND ... is inch, metric, BA, Whitworth.... wotever taps and dies you have or can get.
Bill
