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Re: an interesting mechanical engineering problem

Original poster: Stan <wsmg@xxxxxxxxxx>

How about some Tweco welding cable connectors(brass)? You could grind them so when soldered into the tubing they would be facing straight at each other making it easy to assemble. Then you could have your supports on each side of the joint bolt together to hold it all tight . If you could mount one of the connectors so you could some how rotate it they will lock in making a even better connection. I know they make 400 amp but I think they go higher then that. Just a thought!


Tesla list wrote:

Original poster: Tom Perigrin <tip@xxxxxxxxxxxxxx>

At 08:56 PM 1/9/2007, you wrote:

Original poster: Mike <megavolts61@xxxxxxxxx>

 You can't get cheaper and simpler than some saw cuts and
electrical tape.

-Phil LaBudde
(save your time and money for the IGBT's)

Although I'm a big advocate of going cheaply as possible, I'd have a problem with the visual asthetics of this idea when spending thousands on what is a showpiece.

More than that...   consider the power going through the coil.
Consider what happens if those saw fingers only contact the next section of pipe at a few places, with a little copper oxide in between the two layers of copper metal, giving a resistance of 1 ohm for each joint. The current flub through a joint of 1 ohm and 10 square mm is going to be "fun". Also, as the copper heats it will oxidize even faster, giving us the sort of problem we see with a poorly fitting terminal on a car battery. Heck, I've seen that sort of problem with the poorly made plug on my Chinese Air Conditioner... after 1 year of use I unplugged it and was scared to death by the amount of carbonization evidenced around the prongs.

I'd suggest getting a plug and socket made for each joint. The plug and socket would consist of a 4" OD taper by about 12" long. These should be accurately turned to be +/- 0.001 (or better). Then, get them gold plated with at least 0.005 of 24K gold. Also, there should be a mechanism like a pipe union that snugs the joint together. Clean the joints with warm soapy water before each use, and make a protective covering for transport. That's not going to be a lot of gold..

Sound like MIL-SPEC ? Yeah, probably... but when you are working with something like this, it's better not to screw it all up by trying to save a few bucks on such a critical part.

Failing that, I liked the previous suggestion of Stainless Steel inserts... those can be wire brushed with a brass brush before assembly to assure there is no oxidized layer contributing resistance. I don't think you should use copper on copper, unless you implement a strict protocol of having each joint thoroughly cleaned and degreased before each assembly.