Originally shared by Daryl Bond
While it does include a 3D printed gear (thank you Fusion360 for a spur gear generator!) this is more about the application of a Replicape to machine control in general.
My wifes grandfather passed his old Boxford lathe to me on his passing and it has been a fantastic, if somewhat old and worn, tool. It currently is having issues with current leakage (tingly fingers at 240V anyone?!) and so while the ancient motor is out to get looked at I thought I would address another issue. The gear-train for driving the leadscrew is pretty much shagged and I only have one of the change gears. It is also an imperial machine and I only do metric. The leadscrew itself is fine and so I thought I would look at driving it with a stepper motor. This allows for power feed on finishing passes and possibly, with a rotary encoder on the main spindle, threading operations in the future. So I implemented what is shown below. It is a NEMA17 with 5.18:1 gearbox driving a 20 tooth to 80 tooth (4:1) gear train, total reduction of approx. 21:1. Combined with the reduction of the leadscrew this gives around 1300 full steps/mm. At this early stage I am running the rev. A4A Replicape on a 12V power supply and it stalls out at around 150-200 mm/min.
My next task is to test it when actually cutting. As my main motor is currently broken this could take a while. I suspect, however, that I will need a NEMA23 and higher driving voltage to make it perform at a more acceptable level.