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Lapping valve tapered plug

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Lapping valve tapered plug

Home › Forums › Beginners questions › Lapping valve tapered plug

Viewing 4 posts - 1 through 4 (of 4 total)
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  • 19 September 2009 at 09:19 #43635
    GoCreate
    Participant
      @gocreate
      Hi everyone
      I am building a 3″ scale Allchin, I am looking at making the draincocks for the cylinders which have a tapered plug. The drawing says the valve body and plug tapers should be ground in. I am concerned that if I lap/grind them in using a diamond or similar grinding paste then the abrasive is going to become embeded in the parts. (The drawing suggests bronze for both parts). I was just wondering what procedure is normaly used, is there a method of lapping in the tapers without impregnating the parts with abrasive? At this scale the plug will be 1/4″ diameter.
       
      Many Thanks
       
      Nigel
       
       
      19 September 2009 at 09:19 #4764
      GoCreate
      Participant
        @gocreate
        19 September 2009 at 11:13 #43636
        mgj
        Participant
          @mgj
          I had the same thought on a boiler feed pump tapered valve. Not on an Allchin, but same idea.
           
          I turned the taper on the plug, and the taper for the body reamer at the same setting using a nose radiused cutter – so the finish was pretty glossy. Then I just added a dab of silicone grease.
           
          I havent tried it in service with water, only air, but that holds air without leaking at 150psi.  If it won’t hold water properly I shall just add a small O ring this side of the hole in the taper.
          24 September 2009 at 14:42 #43791
          GoCreate
          Participant
            @gocreate

            Hi Meyrick>>

            Thanks for your reply>>

            I was being led by the drawing saying grind in the valve plug but what you say sound good to me. Basically making the cutter/reamer and plugs at the same setting and keeping the quality good means there should be no or little problem.>>

             >>

            Unfortunately I work overseas most of the year which some what slows progress on my Allchin. However, I have a small Sherline that I use in my overseas apartment so progress can be made on smaller parts. I will make these parts following your advice but will not be able to test them until I get back to the UK in December.>>

             >>

            Again Thanks>>

             >>

            Nigel>>

             

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