Now to put the cat amongst the pigeons.
If you bolt a wire, using a T nut, to one end of a cast iron mill table and then bolt a wire, using a T nut, to the other end then pass a current through the table you will be able to measure a potential difference at various points along the tables surface. Take a look at the size of the conductor in an ammeter shunt and see where the potential difference is measured.
Whilst it would be nice to have everything on a machine at the same potential the deviousness of science will just not allow it. If potential difference exists in an homogonous piece of metal then imagine the situation where various types of metal, plating finishes and fastener materials all having a different PD are combined into one machine.
Earth bonding is a requirement of law within industry and it makes sense that our home workshop meets the same safety standards as industry therefore earth bonding must be carried out in a professional way and there are many good documents suggesting its implementation.
However, we should not confuse earth bonding (which is essentially a safety issue) with signal shielding, they are two separate issues entirely.
For those who would like to re-invent the wheel, by all means connect the shield of your signal cables at both ends but you would be wise to follow the path where others have had success and only connect the shield at the controller end.
It was Eleanor Roosevelt who once said; “Learn from the mistakes of others. You can’t live long enough to make them all yourself”.
Tweakie.
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