Question: what is the difference between drill doctor 500x and 750x?
Answer: The difference between the 750X and 500X is the 750X sharpens up to 3/4″ and the 500 up to 1/2″. The 3/4″ chuck is optional with the Model 500X. The machines are not able to sharpen below a 3/32. Basically, the 750X model does everything the 500X does with several plus points.