polishing clock plates

[dinnie hoekstraParticipant @dinniehoekstra63856]

I am making a pendulum clock and I would like to polish the brass plates – which are about 120 x 180 mm – in such a way that they have a mirror like finish ; but without rounding the edges and the numerous holes in the plates .

does anyone have an idea about how to do this ?

dinnie

[dinnie hoekstraParticipant @dinniehoekstra63856]

[Chris TriceParticipant @christrice43267]

One of the cotton wadding type metal polishes in a tin like the old Duraglit. Great for coins too.

[mechman48Participant @mechman48]

Have a look on YouTube on Clicksprings web site…

**LINK**

He made a beautiful skeleton clock out of brass , his polishing is superb…

George.

[speelwerkParticipant @speelwerk]

Leave the plates a little oversized, polish them to mirror finish, aply a tape to protect the surfaces as good as possible, then cut them to size and drill and tap the holes. Niko.

[IanTParticipant @iant]

A lateral approach Niko – I like it!

Regards,

IanT

[Clive HartlandParticipant @clivehartland94829]

I think you have to go through the whole procedure, that is make sure the plates are flat. Then using a hard block slowly dress off until you have a plate that is, 'Grained off, in one direction and evenly covered. Then you can proceed to polish down through the grades of abrasive and eventually get the polish you seek.

[mechman48Participant @mechman48]

Posted by Clive Hartland on 17/07/2017 09:27:21:

I think you have to go through the whole procedure, that is make sure the plates are flat. Then using a hard block slowly dress off until you have a plate that is, 'Grained off, in one direction and evenly covered. Then you can proceed to polish down through the grades of abrasive and eventually get the polish you seek.

​+1. That's as I remember how it should be done. when I did myS50 I did the crankshaft web in similar procedure, also the crank web on the Vertical cross that I'm on with now… started with 180grit then… 240,400,600,800,1000 wet & dry then finished off with polishing mop, got a nice reflective finish but not a mirror finish…

George.

[BazyleParticipant @bazyle]

The important thing is probably to use a flat hard block for the abrasive not rubber or cotton wool. Then make sure the abrasive paper is flat on it, not lumpy through glue, not curved by being loose etc.

Yet that means lack of contact unless the plate is dead flat itself. So you need a bit of resilience in the block which you can introduce by backing the abrasive sheet with sheets of newspaper.

For plates use a block that is smaller than the plate for convenience but for small parts, eg wheels, it is often better to use a large flat surface (glass sheet or stone chopping board) with the abrasive glued to it.

[Harold Hall 1Participant @haroldhall1]

When I made my skeleton clock ( **LINK** ) I was much helped by an excellent article in the “Model Engineer” magazine. I have searched one of the internet indexes for the magazine and have come up with one which I feel reasonably certain is the article. This was in volume 200, issue 4325, starting on page 564, and by Roger Castle-Smith.

The title of the article is “Finishing a Gold Medal Clock” which gives a clue to the quality of the result being aimed at in the article.

Emphasis has been give in the earlier posts to the need for the abrasives to backed by a flat surface, I used a piece of melamine faced chip board with wooden bars down either side to clamp the abrasive sheets in place. Incidentally, I used around 12 grades of abrasive paper(maybe more) to achieve the finish required.

For the edges of the frames and wheel spokes I used my filing machine using files made of wood and covered by each abrasive grade.

A word of warning, do your utmost to avoid scratches as using a small piece of abrasive and your thumb to remove the scratch will not work as the impression will only show up in certain lighting conditions.

Harold

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