RE: SER1 Horn Bracket

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Graeme.

Emery is what the French Resistance used to destroy machines during the war.
It is what is in, or used to be in, in Valve grinding paste.

When you clean a commutator or other delicate equipment with emery paper
some will come off and may get trapped in the machine. Later it may end up
in bearings or other places.

Sand from sand paper is not so hard and there is something different about
the shape of the grains that I cannot remember. Consequently it is less
likely to get embedded in soft surfaces (like copper commutator bars or
brushes) or caught in bearings and so to cause problems.

How significant the advice is I do not know but it is what was always
taught. Perhaps it is just a counsel of perfection!

I will try and find a reference or two but it will probably only be in old
books. - The "Modern Motor Engineer" Suggests using 00 sandpaper for bedding
in brushes but would not be so crude as to use it on the commutator itself. 

Regards,

Nick. 

-----Original Message-----
From: series1-host@xxxxxxxxx.xxx [mailto:series1-host@xxxxxxxxx.xxx] On
Behalf Of Graeme Aldous

Nick Condon wrote:
<<you can use old flour paper (fine sandpaper) to give a final polish.
(NOT emery paper - never emery on commutators).>>

Nick, can you expand on that please?  Just this morning the latest
edition of LRe has come through the post, and in it is the second part
of my Home Workshop feature on overhauling a dynamo.  In the first
paragraph I suggest cleaning the commutator with emery paper - I've
ALWAYS done it, and I'm not aware of any problems.

Convince me - I may have to get James Taylor to print an 'oops'!

Regards,


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