Old lathes are built to last a lifetime, and while they are a great piece of equipment to have on hand, they lack modern amenities. For example, changing diameters on old lathes involves adjusting a pair of mounts in the gear assembly, which are interlocked with pins that need to be removed for the mounts to swivel to the correct diameter. The same with leadscrew speeds, which are driven by a spindle using said gears.
Tony Goacher is one of those who own an old lathe that was manufactured by Myford in 1949 and decided he wanted to add more functionality by upgrading it with his Leadscrew Buddy, which helped him overcome the limitations mentioned earlier. Goacher coupled his lathe with an Arduino, stepper motor, and several push buttons to control diameters and spindle speeds. He managed to decouple the leadscrew from the gearbox and actuate it with the stepper motor, allowing him to change the variable feed speed.
What's more, Goacher incorporated a rotary encoder to display the carriage position on a homebrew DRO (digital readout). He also designed a seek mode that enables him to direct the z-axis to travel to a set point at a given speed once a home position is set. "The seek function is really useful when doing repeated cuts to the same position on a workpiece, and the generic power feed gives a much better surface finish than I can achieve by hand," states Goacher notes his project blog. "Going forwards, I'd like to add a 'relative step advance' mode where you set a distance, and the carriage will move forwards by that amount relative to the current position when requested."
On a related note, I can't count the number of times I found old lathes like thrown away by neighbors. The biggest question I always had besides, why throw it away, but how did they get it to the curb?