On my mill I do not have a DRO for either the quill or knee. I have a very good Mitutoyo 2 axis though. I may add a second DRO for the z, one that is capable of both summing z+z, and independent display.
I also thought about seeing if a 4 axis Ditron unit Is capable of reading the 2 Mitutoyo scales that I have now on the mill, then I could move the Mitutoyo to the 1660. I'd order a 4 axis Ditron with 2 z axis scales for the mill and 2 scales for my 16x60. That is if the Mitutoyo head unit can read the Ditron scales as well . The idea is to not waste the 2 very expensive Mitutoyo scales that are already mounted on the mill.
I'm pretty happy with the Ditron stuff so far. Very well built, easy setup, minimal chinglish. Ditron has been around at least 20 years from the searches I did. Half the price of Dro pros
I also thought about seeing if a 4 axis Ditron unit Is capable of reading the 2 Mitutoyo scales that I have now on the mill, then I could move the Mitutoyo to the 1660. I'd order a 4 axis Ditron with 2 z axis scales for the mill and 2 scales for my 16x60. That is if the Mitutoyo head unit can read the Ditron scales as well . The idea is to not waste the 2 very expensive Mitutoyo scales that are already mounted on the mill.
I'm pretty happy with the Ditron stuff so far. Very well built, easy setup, minimal chinglish. Ditron has been around at least 20 years from the searches I did. Half the price of Dro pros