Sizing a hole for a glas cylinder

Discussion in 'General Discussion' started by Shapiro, Nov 28, 2011.

  1. Shapiro
    Shapiro New Member
    Hello,

    I have a hollow glass cylinder which is exactly 10mm in diameter.

    I need to fit this cylinder into a hole in my shape; obviously the hole needs to be "10+X" mm in diameter, for some X>0.

    What is a good rule of thumb for "X" so that the cylinder fits as close/tight as possible, but is still guaranteed to fit at all without damaging the shape or breaking the glass? It does not need to be air or water tight, but should not give much leeway for movement either.

    Do I use the "min details" property of the material for "X"? I.e., for alumide I would make the diameter 10.4mm? Or should I rather forget about making a close fit, and add a plenty large X and use an O-ring for a closer fit?

    Thanks!
     
  2. stonysmith
    stonysmith Well-Known Member Moderator
    Honestly, using the "min details" is probably a pretty good rule of thumb. But.. you also need to be aware that certain materials have a shrinkage factor, for example FUD shrinks about 2%

    I don't know where to find the shrink amount for each material.. I just remember the one for FUD.
     
  3. lensman
    lensman Well-Known Member
    I don't think the "shrink amount" for each material has ever been posted. I'd like this info. And it does vary quite a bit for each material.

    Glenn
     
  4. stonysmith
    stonysmith Well-Known Member Moderator