Electrical Contact Material

Searcher7 Inscribed thus:

In that case paper will do what you want ! ie think paper towel.

In English, "burnishing."

Cheers! Rich

Wiping as in cleaning?

Crocus cloth.

Cheers! Rich

I've noticed that when questions are asked responders tend to fall back on what is tried and tested, and they give answers in line with what is proven with whatever application they *think* is being referred to. There is no problem with that, but if someone is thinking outside of the box there is resistance to the new idea, even though the project is not completely understood by everyone else.

There is no need to explain the project. (And it would do no good anyway without pictures).

So basically, the question is simple. But for some reason no one here is getting it. They instead jump on me for not explaining it completely.

I can only conclude that no one yet knows the answer and so I am in uncharted territory as far as what I need. So I will have to experiment with various solid materials in order to find one that will relatively easily scrap the oxide off of phosphor-Bronze so a electrical connection can be reliably made at the voltages I mentioned.

P.S.: I'll say this. The device I'm designing will incorporate a wiping motion *between* when the connections are made, so the actual wiping will not occur between one contact and another, but *before* they come together, which is why I am looking for a different non- conductive material for wiping.

Thanks.

Darren Harris Staten Island, New York.

Masterfully spoken.

Now, if only he would discontinue top posting.

I am reminded of Rodney King's words... :-|

sacrificial anode ?

The PROPER method to clean an electrical contact (pair) *that is meant to be serviceable*, is by a process known as "burnishing". The tool is a flat strip of thin metal with a face surface texture of about 3600 grit. Short of having such an easily obtainable tool, the best and second and ONLY other proper method is the "paper" suggestion, but I would choose something a little stiffer than paper towel, also exhibiting far less fiber. So, I would use matchbook thickness or business card thickness media. A business card, in fact, is a good, if not excellent choice. Not an enameled version though. The paper is a refined wood fiber pulp media that has the perfect mild abrasion qualities required for the task. A true abrasive cloth is not proper, and is meant for other applications. If the contact faces have become pitted or damaged from an arcing/ current inrush event, you will likely not be able to get the original face shape back. If it is your lawn mower "points", you replace them, though I have made several keep on tickin'. Those WOULD require at least one of the contacts be abraded.

For normal every day use though, you should never have to worry about it, because any contact(pair) made from a proper media will be one of those we (science) knows to be of a low oxidation factor, or of one where it matters not. I believe, and only from _some_ experience, so not expert, that Platinum is most common in small scale applications, Gold is second, and most common due to modern electroplating and alloys of gold being able to be referred to as Gold, another is Silver, often used for RF where refined HV arcs would be encountered and oxidation layers are OK.

Use the paper. Non conductive AND high Volt per mil isolation? Use transformer paper. Top brand is "Nomex". Made by DuPont many decades ago, and barely matched (others exist). Something on the order of 1500 Volts per mil, IIRC, though I would recommend at least 5 or 10 mil media to acquire the stiffness to push as well as pull on it while clasped by the "contacts". 15 mil even better.

Have a nice day...

As I mentioned, outside of data lines, voltages will be small(-5V,

Thanks.

Darren Harris Staten Island, New York.

transformer paper is wood fibre impregnated with some sort of heat resistant resin. 15mil is approximately business-card thickness. in my experience it's much stiffer than ordinary paper products.

If you don't like that you could try FR-2 or FR-4 printed circuit board material, FR-2 is wood-fibre based FR-4 is glass-fibre based.

FR4 is available in amny different thicknesses.

ion? =C2=A0Use

Well, with glass, being harder than steel, those contacts would abrade, i.e. wear.

The x-former paper is the standard in so many sci circles where electrical isolation is required. There are even zero outgass varieties for high vacuum use.

Pieces of ARE in fact used as structural elements in mechanical systems as well. It is cheaper than circuit board media, and they make it in sheets... big sheets.

Cut to order or sent in 4 foot wide rolls if ye like. Google Du Pont Nomex

I'll bet some kid could make one of those gravity cars from it and do well. Strong stuff. :-)

Nunya Inscribed thus:

The type of paper towel that I referred to and have used many times is the hard folded ones, about a foot square and usually found in factory washrooms. They have a hard lint free surface which makes the material suitable for this purpose. I've also used the hard toilet sheets, the ones with a smooth surface on one side, for small contact points with good results.

I would suggest that the type of contacts (points) that you refer to are the only type that a contact burnishing file should be used on. I recall that in the old "Kettering Ignition" days, a suitable "Contact File" was always a must have toolbox item. As was a spare points set and condenser !

Back in the days of punched cards, field service engineers would often use an (unpunched) card for this purpose. It was just the right abrasiveness and stiffness for cleaning many things including contact surfaces and disk head surfaces of that time. Cards were cleaned of loose dust during manufacture to prevent dust shedding into card punches and readers. They were also made of paper which doesn't soften if it gets wet, so you could if necessary use water or a solvent on them too, whilst still staying abrasive and without going soggy (although they were mostly used dry).

Paper tape had the same properties, but was thinner, and finer level of abrasiveness.

That makes things clearer.

I'm now just trying to visualise the arrangement you are proposing.

The idea was to attract erosion else where.

Guess you've never seen S-anode contacts. Similar to wetting.

Jamie