Hi,
From time to time I have seen mention of welding turntables. I want to build my own turntable. I have a suitable piece of 3/8" plate and a large "lazy susan" bearing. The problem, of course, is obtaining a reliable, low-resistance grounding connection. At one point I think I saw a post from Ernie mentioning the use of carbon brushes such as those used in commutator motors, but I have not had much luck finding brushes with shunts that could potentially handle 200A, even if I used multiple blocks. I suppose I might use carbon rods such as those used for carbon arc gouging, or perhaps there are suppliers of replacement brushes for large DC motors. If so, I haven't found them. My usually reliable sources such as McMaster and Grainger have not been helpful this time.
Another possibility is a spring loaded copper stud that bears against the underside of the table. This seems to suffer from a high likelihood of oxidation and arcing leading to a high-resistance connection. Even a few ohms is too much. Then again, maybe it would be ok - I really am not sure.
So, for those of you who have seen commercial turntables or who have built your own turntables: How was the grounding connection made?
Thanks in advance for any useful info you can provide.
"Joe Blow"