Is it safe to use a conductive frame as a ground?

TinManSA:
My original question was to determine if I could use the aluminium frames, steel axle and steel bearing (all conductive material) as "common" (GND), thereby freeing up channels on the slip rings.

Ron_Blain:
You can't have a path to ground through the bearings. Rest assured as pointed out, really bad things will happen.

The problem with connecting through the bearings is that they have only 2 small points of rolling contact. When(not if) it rolls over a tiny piece of grit contact is lost and then re-established. this causes arcing further degrading contact. If you looked at the signal with an oscilloscope you would see constant interruptions in the signal that get worse over time.

I hope this helps you to understand what everyone is trying to tell you.
Les

I think we all understand you.

TinManSA:
My original question was to determine if I could use the aluminium frames, steel axle and steel bearing (all conductive material) as "common" (GND), thereby freeing up channels

The problem is the conductive parts have poor unreliable electric contact. It may work flawlessly but it may also cause all sorts of glitches.

The answer is still no. What is the maximum current the ground path will see? Do you want a ground path through a rotating bearing? Again, the answer to your question is no and if you are part of the design the why should be apparent.

Ron

TinManSA:
@Perry:

I am not pushing for "Yes, you can do it" answer.
The point of asking a question, in my case at least, is to get an answer and an explanation of why it can not be done.

Instead of asking for clarity, I am confronted with semantics. JohnRob is the only one who has made an effort of trying to understand what I am looking to achieve.

If the answer is NO, at least offer an explanation so that I can learn. Isn't asking questions an integral part of learning ?

Tino

First, what your saying you want to do is an easy concept to understand. We get it, got it?

A person touching a frame at circuit common and standing on the floor can experience current flow resulting in death.

Idahowalker:
A person touching a frame at circuit common and standing on the floor can experience current flow resulting in death.

But pretty unlikely at 12 V. :roll_eyes:

@Hutkikz: Thank you for your reply, it makes perfect sense what you are saying. Thanks for that!

@Smajdalf: Your reply is in line with what Hutkikz is saying. Thanks!