graphite bushes/bearings ?

[roy entwistleParticipant @royentwistle24699]

Michael No one was mocking you It was a straight forward question

[Russell EberhardtParticipant @russelleberhardt48058]

My reason for mentioning that some motor brushes contain copper is that copper is very poor as a bearing material and may result in too much friction.

Nothing to do with electrical conductivity!

Russell;

[jason udallParticipant @jasonudall57142]

I suspect the “worry” of M W. Was over electrostatic concerns
.
One ) graphite -carbon- and brushes for motors all conduct rather well and in electrostatic terms equally.

Two graphite vs motor brushes..

Firstly motor brushes are not fixed composition. .they are blends of graphite /binder /copper/ rarely now lead.
If one lucked out one might get a low copper brush and it might have good/excellent friction behaviour.

In low temp difference stirling engin there is on this scale little torque so along with good seal we also need lowest friction achievable. .this is part of why these low temp difference engins are largely recent due to material availability.

[Ex contributorParticipant @mgnbuk]

I raised the subject at work today and, as previously, the cost of processing such a small order is deemed to be much higher than the cost of such a small piece of graphite, so not really viable.

But I can supply a piece (the offcut to hand is approx. 14 x 20 x 85mm fine grained isostatic graphite) FOC subject to receiving pictures / a video of the completed engine which the company might use on it's website as a "general interest" application story.

If that is acceptable, PM me your address details & I'll post the piece out (the company will provide the graphite & I will stand the postage).

Nigel B.

(edit for typo)

Edited By Nigel B on 24/02/2016 10:03:16

[Ian S CParticipant @iansc]

Been doing a bit of hunting, found this. JC4 grade, strong, fine grain, machinable. Another one is Poco grade carbon, this one contains copper. Then EDM grade.

G.E. Howell sell's it by the inch, 3/8"D, 5/8"D, 1"D, at $1, $1.50, $2.50, this is for pistons.

Ian S C

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