Geometry question

Discussion in 'Replica Props' started by DarthBish, Feb 22, 2006.

  1. DarthBish

    DarthBish Well-Known Member

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    OK all you geometry wizzes out there...

    I have a pipe that is 1 inch in diameter that I want to enclose in a hexagonal "sleeve"

    How do I calculate the sige lenghths of the hexagon??
     
  2. mverta

    mverta Sr Member

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    Strictly mathematically speaking, each side length must equal .577". I did it in my CAD software, I don't know what the formula is. Keep in mind it would have to be slightly larger than this so there's a molecule of air space in there or whatever :p

    _Mike
     
  3. Macklin

    Macklin Well-Known Member

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    Sorry to hijack, but I have a similar question.

    What diameter should a press-fit part be in relation to the hole? Say I have a 1 inch hole, what diameter should a part be to press snugly inside it ans stay put?

    Think Chen's Obi emitter from a few years back.
     
  4. Prop Runner

    Prop Runner Sr Member

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    [​IMG]

    :D

    - Gabe
     
  5. mverta

    mverta Sr Member

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    ...NICE....


    _Mike
     
  6. Prop Runner

    Prop Runner Sr Member

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    To be honest, it depends on the material and tolerances, but typically you want the inserted object to be 0.0001" - 0.0003" larger in diameter than the receiving hole:

    [​IMG]

    God, I hope this does't turn into an "Ask Gabe" thread. :lol
     
  7. Macklin

    Macklin Well-Known Member

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    Heh. Looks like it's headed in that direction. :)

    I'm thinking T-6061 aluminum. Did you mean to say LARGER?

    Thanks,
    Patrick
     
  8. LeMarchand

    LeMarchand Sr Member

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    :lol :lol :lol :lol Oh god, i can't stop laughing
     
  9. Prop Runner

    Prop Runner Sr Member

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    For Marc: yes, size matters. :D

    Patrick: yes - think about it: anything that's press-fit HAS to be larger than the hole. The material around the hole will expand a bit to accept it. Aluminum is soft, so it's more forgiving than steel if tolerances aren't dead-on accurate. If the diameter was SMALLER by the same amount, it would then be considered a removable SLIP-fit insert.

    - Gabe
     
  10. Treadwell

    Treadwell Master Member RPF PREMIUM MEMBER

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    Dear Dr. Gabe:

    What is this rash? Am I normal?

    -Concerned in Milwaukee




    :D
     
  11. LeMarchand

    LeMarchand Sr Member

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    For proprunner :p ;)

    Don't know what diameter you need, but you'd better stop dating Proprunner, BWHAHAHAHAHAHAHA..... :lol :lol :lol
     
  12. airhead

    airhead Well-Known Member

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    I don't have the tolerences here, but there is always a thermal press-fit - where one part is heated to expand and then, when the other part is inserted, the first contracts for a tight fit (can be done the other way with the inserted piece being chilled - like with liquid nitrogen). Or, differential thermal expansion where both pieces are heated, but one has a higher thermal expansion rate for fitting or disassembly. Like the transmission cases on my bike - 350 degrees in the oven for an hour.

    db
     
  13. Prop Runner

    Prop Runner Sr Member

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    You're a STAFF member and you're asking ME? :lol

    To quote Leia, you're either very brave or very stupid. :D

    All in fun, of course. From the descriptions in your PM, your rash sounds a lot like the Scottish Rosey, and that generally comes from intimate contact with sheep....

    Is there something you wish to share with us? :love

    - Gabe
     
  14. Macklin

    Macklin Well-Known Member

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    *gazes into the distance*

    I know kung-fu...

    Thanks, Gabe. Glad you're here to set us all straight.

    Patrick
     
  15. DarthBish

    DarthBish Well-Known Member

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    Thanks for all the help, you are ALL legends :)
     
  16. Prop Runner

    Prop Runner Sr Member

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    Like Kane, I continue to walk the earth, resolving the world's geometry and press-fit crises...

    ... The Legend Continues...

    :lol
     
  17. Mechinyun

    Mechinyun Sr Member

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    :lol kekeke
     

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