Polishing Brass – or where to get P5000 paper

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Polishing Brass – or where to get P5000 paper

Home Forums Beginners questions Polishing Brass – or where to get P5000 paper

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  • #258235
    Robin Graham
    Participant
      @robingraham42208

      A while since I started this thread I know, but as there was some interest I thought I should report on a recent discovery – a box of diamond pastes hidden in a drawer. I have no idea of why or when I bought them (from Arc Euro according to the labels), but the kit goes down to 0,5 microns – hand polishing down to that with those bog-standard yellow dusting cloths gives a very fine finish indeed. As an experiment I tried to further refine the surface with Autosol, using the same technique, but it was a retrograde step.

      Rob.

      Edited By Robin Graham on 28/09/2016 00:10:03

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      #258238
      Michael Gilligan
      Participant
        @michaelgilligan61133

        Very interesting, Robin … Thanks for reporting back.

        MichaelG.

        .

        P.S. … Don't tell John Stevenson [he doesn't believe microns exist].

        #258252
        John Stevenson 1
        Participant
          @johnstevenson1

          They do but only if you have a million of them otherwise the angels fall off

          #258266
          Clive Hartland
          Participant
            @clivehartland94829

            Just seen this, a good polishing base is some Chamoi leather stretched over a piece of suitable wood and then apply polishing medium to the leather. Keep wet with medium used.

            Clive

            #258267
            Chris Evans 6
            Participant
              @chrisevans6

              I spent my working life in Injection mould making where hardened steel moulds had to be polished to mirror like finishes. Think transparent plastic like spectacle lenses. Car door and lorry mirrors. I could never achieve the level of polish the polishing section could. They would make comments like "highly polished and deeply scratched"

              After going through lots of abrasive grades diamond past was used with a special lubricant, paraffin would scratch the polished surface.

              #258335
              Ajohnw
              Participant
                @ajohnw51620

                There are a number of polishing and lapping options around and on this page.

                **LINK**

                John

                #259264
                Robin Graham
                Participant
                  @robingraham42208

                  Thanks for further replies. As I now have about 5 million (× 10-6 orders for this shiny thing I'm making, it's been worth making some systematic experiments based on the info in this thread and in other places.

                  My aim was to polish the faces of two inch diameter brass discs as quickly as possible. I tried various methods – going through the grades of wet'n'dry on plate glass followed by tripoli and the blue compound on machine driven mops, going through the belts on a linisher, Autotosol on a mop at various stages etc etc – I tried many permutations.

                  It turned out (to my surprise) that I could take machining marks out in less than a minute per face using an A6 (roughly P2000) Trizact belt on the linisher without going through the grades – the belt was already on the machine,and laziness was the mother of this discovery for sure. Trizacts cut fast and don't seem to clog at all.

                  From there, Autosol on a machine driven G-type loose-leaf cotton mop gave about the same finish as Tripoli/blue compounds, on their individual G mops , but much faster. I had assumed that aggressive and coarse went together, but not so.

                  Final hand polishing with 2, 1, 0.5, 0.25 micron diamond pastes gives a specular surface – but if a fly coughs on it….

                  Rob.

                   

                   

                  Edited By Robin Graham on 04/10/2016 23:23:56

                  #259304
                  Neil Wyatt
                  Moderator
                    @neilwyatt
                    Posted by Robin Graham on 04/10/2016 23:13:59:

                    Thanks for further replies. As I now have about 5 million (× 10-6 orders for this shiny thing I'm making, it's been worth making some systematic experiments based on the info in this thread and in other places.

                    :

                    :

                    :

                    Final hand polishing with 2, 1, 0.5, 0.25 micron diamond pastes gives a specular surface – but if a fly coughs on it….

                    I think my Jovilabe is going to have an enclosed gearbox

                    #259319
                    KWIL
                    Participant
                      @kwil

                      Up to P7000

                      **LINK**

                      #259414
                      Robin Graham
                      Participant
                        @robingraham42208

                        Had to google Jovilabe – wow, I want one.

                        Thanks for the link KWIL – duly ordered. An Amazon reviewer bought them for getting fine points on pencils – and I thought I was being obsessive/compulsive! A mild case it seems.

                        Rob.

                        #259415
                        Michael Gilligan
                        Participant
                          @michaelgilligan61133
                          Posted by Robin Graham on 05/10/2016 22:06:11:

                          Had to google Jovilabe – wow, I want one.

                          .

                          Robin,

                          I hope you found this excellent video **LINK**

                          http://brunelleschi.imss.fi.it/itineraries/multimedia/Jovilabe.html

                          MichaelG.

                          #261787
                          Neil Wyatt
                          Moderator
                            @neilwyatt

                            I must admit I am not getting a gold-medal finish on my gears…

                            But I am getting a reasonable polish (mirror-like with a few flaws) following this procedure:

                            Using wet and dry on a my granite 'surface plate' I am doing an initial run on 180 grit untill all machining marks disappear.

                            Then at 90-degrees with 280 grit.

                            Lastly circular movements with 400 grit until you can't see any straight lines, 30-40 seconds, perhaps.

                            The above takes 3-4 minutes for an average brass gear about 30mm diameter.

                            Final polish is with silver/brass liquid polish on a sheet of 1/16" ply – which goes jet black in seconds!

                            This certainly achieves a polish my mum would have approved off, if not a gold-medal result. I think another stage with 600 grit would probably be the way to go for that.

                            Foolish me made all the gears with a 1mm boss underneath, so I am not doing as through a job but these surfaces will only be visible as reflections in other gears anyway :-0

                            Neil

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