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Cylinders : Gunmetal v Cast Iron

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Cylinders : Gunmetal v Cast Iron

Home › Forums › Locomotives › Cylinders : Gunmetal v Cast Iron

Viewing 5 posts - 1 through 5 (of 5 total)
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  • 10 August 2011 at 14:02 #73120
    Steambuff
    Participant
      @steambuff
      Sorry for asking a simple question but as a beginner I am getting conflicting advice.
       
      I am at the stage where I need to think about ordering the castings (or material) for my loco cylinders.
       
      I have the choice of Gun-Metal or Cast Iron. (In all my 16mm loco’s I used Brass).
       
      What are the Pro’s and Cons of Gun-Metal v Cast Iron for the Cylinders and Pistons. (Other than Cost) Also can both be made of the same material – The piston does have a rubber ring on it.
       
      Many Thanks.
       
      Dave
       
      10 August 2011 at 14:02 #1029
      Steambuff
      Participant
        @steambuff

        Pro’s and Cons of Gunmetal v Cast Iron

        11 August 2011 at 19:39 #73211
        Jim Nolan
        Participant
          @jimnolan76764

          Dave,
          Like all technical questions on this forum you can hear the tumbleweed blowing through the answers. You should have asked a question where the answer was an opinion not something that required a bit of knowledge.

          What might help and bring more of the knowledgeable persons on here out of the woodwork is if you could expand on gauge / scale as it might give the responders a clue as to how to advise you

          Jim

          Edited By David Clark 1 on 11/08/2011 19:59:10

          11 August 2011 at 19:55 #73212
          JasonB
          Moderator
            @jasonb
            Posted twice

            Edited By JasonB on 11/08/2011 20:07:50

            11 August 2011 at 19:59 #73213
            JasonB
            Moderator
              @jasonb
              Well I’ll chuck in a couple of thoughts.
               
              CI
              -Possible risk of hardspots due to parts of the casting cooling too rapidly.Not something you can spot straight away, there are ways around it and a good supplier may well replace a defective casting
              -Risk of rust in the cylinder if left with condensate in them
              -Some people don’t like the dirty nature of the material when machined, does not bother me.
              -Easier to work than GM as it does not grab when drilling or tapping
              – Less expensive
               
              GM
              -Less risk of corrosion
              – Softer material which can easily be marked by chuck jaws or over clamping
              – Can grab when drilling and needs a sharp tap to avoid problems when threading
              – Expensive compared to iron
              – Unlikely to have hard spots
              – Probably less abrasive on “O” rings than iron
               
              Iron on iron is not a problem but GM on GM could cause gauling, however the piston does not actually touch the cylinder wall, it will have a littel clearance and the O ring will be whats in contact with the cylinder not the actual piston. So in this situation it does not really matter if the metals are alike or disimilar.
               
              J
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