never seen a dedicated machine for it, only regular manual lathes with diy add-ons mechanically linking the spindle to a cam to the disconnect crossfeed. With a cam and no feedscrew, i can see how it would run at something close to regular speeds, but in the sense that for diy making this would a rare activitiy, running at 20 or 30 rpm so the y screw could keep up would be no big deal, in other words the cam action is replaced by the y axis servo action
making hobs isn't a burning issue for me, but it did seem to be something a cnc lathe would have the capability to readily do - whereas it takes extensive mechanical modifications to do on a manual lathe
I've also always wanted a belt drive lathe like the high end tool room models - a VF drive, encoders on spindle and axis and belt drive on the spindle has appeal
