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ANSI RC, LC etc. seems to deal with shifts

  1. Sep 2, 2008 #1
    I have a clearance question. I’m in need of understanding the clearances and tolerances associated with the sliding parts in a sliding bolt fire arm. The moles are really going to hate this. After some time goggling, reading, and with a year of mechanical drafting, I estimated that ANSI RC 8 or 9 meets my application, around .005 to .012 of an inch, clearance for a sliding bolt. I downloaded a schematic from scribd.com, that has .013 diameter clearance between a sliding bolt and its receiving part. Here is where I need help, ANSI RC, LC etc. seems to deal with shifts and holes, I’m not sure how much my part having right angles affect these clearances, i.e. my sliding part isn’t round. My doodling has .006 total clearance there, is that too small, and is the higher end of .013 a better fit?

    Thanks for any help,

  2. jcsd
  3. Sep 3, 2008 #2


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    Science Advisor

    This is really a question for someone very involved with firearm design. I can pull a clearance that I would think would work based on my experience, but that would be lacking the specific knowledge of application.

    When it comes to tolerancing, experience in the particular application field is incredibly valuable. What effects does dirt and contaminants from firing have? What kind of lubrication is required? What tolerances are there on the straightness of the bore? It's a bit of a tough question to get right. However, we can take a stab at this if you can give some more of a description. A picture would help immensely.
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