Hey Art , perhaps a big part of this for myself , is that I hardly EVER had a DRO on anything , starting from 1974 . Working on machines from research laboratories, Navy Bases and Ships, to job shops.
However......? One of the first things I had available at my Home Shop was the unit for the QUILL. Got a super deal on a Mitutoyo unit,it must be nearly 20 years ago now. Of course that unit read DIRECTLY on it's own display.
Only for me to discover in usage , was that it interfered with my typical use of the STOP. It required removing the "Push Button" QUILL stop I had on the mill. Yes the *Clamp On* Quick Stop unit used in it's place was also often impossible to use.? I guess I had simply not realized just how often I used my 2 Boring Heads ! ?
As far as the KNEE goes , I have hardly ever used a mill that had that readout in place. A Dial Indicator had always verified how linear the dial was overall so in general I never worried about it.
Having worked with various folks who were very much VISION challenged compared to myself? , I suppose that could be a real justification.
I have worn glasses for over 50 years , but had frequently been recognized or even complemented for my *Sharp Vision*.
Also , I must reluctantly admit to a , well , personal failing on this matter.......procrastination !?! ?
I have a two axis DRO that -came - with my dilapidated Bridgeport . It was almost brand new.
The lip SEALS have turned to STONE it's now so old. I REMOVED IT almost as soon as I got it.
I want to apocryphally say , it was *GLUED ON* !
It was in no way *SQUARE* , Parallel , Plum or even remotely SOLID. I didn't want to risk it potentially impacting ANYTHING I machines at the time. Most of which were Race Car oriented.
Alas , the proper installation of which , has just never been a priority in two decades now. ?
The LIP seals are long gone on the scales , but the low grade unit of the day still powers up and displays as designed.?
Marty