Brass or copper spheres

[telluric42]

Hi all

planning on building a Wimshurst Machine for some HV electrostatic experiments and finding it hard to find brass or copper balls for the end electrodes.

I'm in Australia, Melbourne. any tips would be great.



thanks
T42

[neptune]

Been there , done that Use Brass doorknobs .For vey large ones , try the copper floats from old Ballcocks . Steel ball bearings will work  , or a plastic ball painted with a paint containg metal or carbon[mix your own ] Improvise!

[neptune]

You can sometimes find brass balls on old decorative lamp fittings or chandeliers .

[TinselKoala]

Cabinet knobs for the small ones; keep looking, you will find ball knobs in the "better" builder's supply houses.

Larger ones can be doorknobs.

Those Chinese "exercise balls" that have chimes inside and come boxed in pairs--- these are cast iron with a nice chromeplated surface and can be easily drilled and tapped to accept a mounting screw. They also come in a few different sizes and are cheap.

Ball Bearing balls are hardened and much more difficult to drill, but conductive epoxy can be used for mounting.

Tank floats can be had in larger sizes, made of steel or sometimes copper. I have also used copper toilet tank floats, but they have sharp edges that need to be taken care of.

I have not had good luck with conductive paints on nonconductive spheres. They seem to leave a rough surface, and can also burn or spall off in little points as a discharge happens.

But: You can get styrofoam spheres in all different sizes from craft stores, and cover them with aluminum duct tape, carefully smoothed so as to not leave sharp corners or edges on the tape.

[ramset]

Telluric42
A suggestion ,
Brush plating ,If Tinfoil works [but smooth] brush plating could be an option,I make a very simple machine that I sell for Brush plating of  Nickle copper Gold etc...........
Rediculously simple to do ,if you can find nice Shiney chrome plated spheres ,strip the Chrome off  w/reverse polarity mild acid or base solution,and replate copper nickle gold ,whatever?,Takes Milli amps to do.
Google brush plating ,call some local vendors for "Samples"
You be plating in no time!!
And it will at least look beautiful!!
Or you can buy Silver paints {real silver}
And plate over those
Or try the foil?

Chet