We see a lot of CNC Machines here on Hackaday but not too many of them are lathe-based. [Jim] sent us an email letting us know his dissatisfaction regarding the lack of CNC Lathes and included a link to one of his recent projects, converting a small manual lathe to computer control. This isn’t some ‘slap on some steppers‘ type of project, it’s a full-fledged build capable of tight tolerances and threading.
The project is based on a 7×12 Mini Lathe. There are several brands to choose from and they are almost identical. Check out this comparison. [Jim] started with Homier brand.
The first thing to get upgraded was not related to the CNC conversion. The 3″ chuck was replaced with a 5″. Changing it over was easy using an adapter plate made for the task. For the X Axis, the stock ways and lead screw were removed and replaced by a THK linear slide. This slide only has 2.5″ of travel and is perfect for this application. The travel being so short allowed the final eBay auction price to be under $40.
Just like the X Axis stock hardware, all of the Z Axis parts were also ditched in favor of another eBay find, a 10mm ball screw and nut. [Jim] had to make his own brackets to mount the motor to the bed and the ball nut to the carriage. The new brackets bolt up to the machine in the same manner the stock parts did making the install a little easier.
The lathe is controlled by an old Pentium 4 computer running Mach3. The step and direction signals exit the computer via parallel port and make their way to a pair of Gecko stepper motor drives. A home-made power supply provides 36vdc for the NEMA23 stepper motors. A Hall Effect sensor is mounted to the spindle and provides spindle speed information back to Mach3 so that it can time the step commands while cutting threads. The end result is a sweet and capable Lathe we are happy to add to the list of CNC Machines featured on Hackaday.