At first, due to my being electrically challenged, I wasn't getting the subtle hints he (Al) was making on the subject. Then I read one where he came out and directly said the same thing you're saying.
My system isn't quite to the point where I need to get all that done as I'm still doing the mechanical aspects of my IH mill conversion. But I intend to go ahead and tie my "-" connections to my star ground point when I get that far along. Well, that is the 5vdc for the CNC4PC C11G card and Gecko's and the 24vdc for the cooling fans.
Did you do the same with the larger power supply for the servos? I'm thinking yes is the answer as it makes sense to me, the electrically challenged. But what do I know on the subject, let me answer that one, nothing! Then, here is the one that has me stumped. The C11G manual says, in regard to the 12vdc power supply for spindle control through a vfd .
It requires a +12VDC@ 20mA power supply to operate.
WARNING: To keep the output signals optoisolated, these must not
have common ground or connections to current with other circuits you
So, I'm thinking this one stands alone with no common ground. I intend to ask Arturo that question before powering up the mill for the first time, but haven't yet. Your thoughts?
And what about the green ground cables coming out of the servo motors? Back to the star ground as well even though the "-" cable already goes there?