synthetic graphite

[satdaveuk]

Hi all,

I know a good alternative for the binder:
It's cheap too:
- Polystyrene (styrofoam)
- Acetone (solvent)

Put some acetone in a glass. Solve a little bit styrofoam in the acetone. Put the graphite power to the solvent. Mix it all together.
The mixture should be paintable in its consistency.
If the graphite paint is getting dry, put some acetone into it.

No problem when the graphite paint is getting dry. Put acetone to solve it again.

You have to experiment with the amount of styrofoam/graphite/acetone content. But this binder is very easy to make and cheap as well.

Be careful. Acetone is harmful and is drying quickly. Use it outdoors only.

Cheers,
Aziz

shall try that first because both items I have here , im really excited and feeling positive about this, should have delivery of the graphite this week.
If it works well and does the job its going to be of such help to me and other members here not just for coils but also shielding of project cases when using styrene or pvc.

Thanks for the feed back so far hopefully there maybe more.

Regards

[homefire]

I don't know for sure, but I would think that Acetone would mess with the lacquer on the magnet wire?

Just thinking out loud.


I do know it will kill almost any plastic known to man.

[Aziz]

I don't know for sure, but I would think that Acetone would mess with the lacquer on the magnet wire?

Just thinking out loud.


I do know it will kill almost any plastic known to man.

Sure, it would.

Use paper tape before painting the graphite shield onto the coil bundle.
It needs some time to dry. It must completely dry of course and depends on the layer thickness.

Aziz

[satdaveuk]

I don't know for sure, but I would think that Acetone would mess with the lacquer on the magnet wire?

Just thinking out loud.


I do know it will kill almost any plastic known to man.

Yes your right I wasnt thinking of applying directly onto laminations but rather onto the binding.
I found acetone on its own with most plastics is ok, but paints glues etc its violent, good cleaner though for after glueing, and cleaning copper pcb before transfering circuit images on it via laser print.
Acetone when said comes out like acidtone, and its the acid bit that scares alot of people off.
I have some acid here I aquired along time ago which is 85% sulphuric, now thats what you call deadly, only used it once to clean some steel off for a project and the fumes burnt my eyes nose throat, and any spec gets on your skin is like been burnt with a fag end. good for cleaning roman coins though only joking of course haha

Regards

[satdaveuk]

I just read on another forum that rubing graphite onto mylar actually takes, so i need to try it out because the o/c problems on creases that put me off from using mylar maybe can be cured, which would be great because if wound conductive side up cant see any problem just rubbing over with the garaphite and checking for continuity.
Its another angle worth investigating will let you know because I have a 12" coil here prept with mylar and nothing else.

Regards

[satdaveuk]

I was getting good results with 60/50 graphite/pva and a dash of acetone but after a few days resistance was getting higher due to the copper conductors reaction ie went green, to what i think was the acetone, so its a bit of a bummer, next im trying with same mix but with water and see what happens.
Trouble with these tests are they start out with good results but how long the life span can only be found as time goes on, anyways at last ive learned one way not to shield.

Regards

[6666]

Sat
try tinned copper wire if you can get it, or make it.

[woodbob123]

Received my tub of graphite from e-bay. Have had this idea of using tape
Today i laid out a strip of duck tape sprinkled on a layer of graphite and rubbed it in to adhesive, measured around 20K ohm over 60cm length. gave it a good shake outside to remove any loose graphite. Connection made with some EMI shielding tape i have, copper with conductive adhesive ( used a lot in the past to make connections on to ali strips on solar panels which lasted years). Don't have part number but purchased from RS. radio spares in uk. First strip made connection each end and center covered with a second strip of duck tape and pressed together hard. have 20k between ends will leave to let glue set/stabalise then see if i lose continuity after twisting and pulling. So far so good

[DOOLEY]

just had a thought,carbon paper as used between paper to do copies,conductive ???

would i be right to asume that we don't want a highly conductive shield which could develop eddy currents and limit performance and may be detected ??

and that a reasonably resistive shield would still provide effective shield but would be less detectable , would this be better ??

if so , then what would be the magic resistance to aim for for a shield ??

[Midas]

Received my tub of graphite from e-bay. Have had this idea of using tape
Today i laid out a strip of duck tape sprinkled on a layer of graphite and rubbed it in to adhesive, measured around 20K ohm over 60cm length. gave it a good shake outside to remove any loose graphite. Connection made with some EMI shielding tape i have, copper with conductive adhesive ( used a lot in the past to make connections on to ali strips on solar panels which lasted years). Don't have part number but purchased from RS. radio spares in uk. First strip made connection each end and center covered with a second strip of duck tape and pressed together hard. have 20k between ends will leave to let glue set/stabalise then see if i lose continuity after twisting and pulling. So far so good

Is that tape made from rendered down ducks or is it called that because its designed for catching ducks, like flypaper?

Slightly more on topic has anyone tried nickle powder? Its quite a bit more conductive than graphite so you wouldn't have to load up your epoxy or whatever with so much powder. The end result should be much easy to work with and more durable for the same conductivity. Of course I'm sure it costs more too..

Midas

[woodbob123]

should have used the correct term which is duct tape sorry

When we mix a powder such as graphite with an adhesive each particle is coated and insulated. connection is also coated or laid over the adhesive. As we always connect to -V or earth surely there should be a DC path or do we rely on coupling between elements ( struggeling to make and understand what makes a good coil )

[satdaveuk]

If you use synthetic graphite its 98-99% carbon and thats from the manufactures I spoke to, its deposits left when there making brushes for motors etc, they refine it so its like dust, its cheap and mixed with 50-50 hard glaze varnish and a spec of turps it brushes on like paint and goes off like rock, and sticks like **** to a blankit.
I done styrene housings and coils prepared with paper hospital tape, up to now havent look back, its the best ive used todate far as shielding.
Soon as I have time will do a proper thing on here of how to do ok.

Regards

[6666]

Ok I know I will get canned for this
but cannot resist Woodbob
back on topic now

[Midas]

should have used the correct term which is duct tape sorry

When we mix a powder such as graphite with an adhesive each particle is coated and insulated. connection is also coated or laid over the adhesive. As we always connect to -V or earth surely there should be a DC path or do we rely on coupling between elements ( struggeling to make and understand what makes a good coil )

No need to apologize we all knew what you meant, I was just trying to be funny.

The situation you describe where the conductive particles are all insulated from one another is what would happen if you didn't have a high enough loading in your mix. As you add more particles they are forced to start touching each other and make a bridging network through the non-conductive binder which is what you want.

Midas

[woodbob123]

no it's ok could not think of a funny reply, that's the stuff
even overloaded with graphite glue will coat each particle as it's mixed and the better the mix the more even the coating, but it works yes. what level of resistance are we aiming for very high and very thin would be my best guess. would it be in the M or K ohm ranges per 50cm
later will think of the perfect duck ending ATB