Bob Puhakka on Bifilm theory

Discussion in 'Links to useful information' started by Gippeto, Feb 2, 2019.

  1. oldironfarmer

    oldironfarmer Silver Banner Member

    I've done my four. Have one still on 95 lbs test for a week now. I think the water has been absorbing air, the pressure is down to 87 psi and stable for four days.
     
  2. oldironfarmer

    oldironfarmer Silver Banner Member

    I took a stab at interpreting bifilm theory application to small flasks/castings.

    Comments appreciated.

     
    dtsh, Tobho Mott and Petee716 like this.
  3. Tobho Mott

    Tobho Mott Silver Banner Member

    It was easier to follow than Bob's explanations on Perry's YouTube. Very nice.

    Jeff
     
    oldironfarmer likes this.
  4. PatJ

    PatJ Silver Banner Member

    Don't forget that Bob's bifilm theory apparently comes from John Campbell's work, and John Campbell's work includes 10 rules for good castings.
    If you pay attention to the bifilm theory and ignore John Campbell's 10 rules, then you most likely will have achieved nothing.
    The big pictures has to be kept in mind when casting metal; it is not just one theory but a number of complex interactions that must be understood.
    .
     
  5. ESC

    ESC Silver Banner Member

    Good job Andy, but no explosion:).
    Seriously, that is a lot of information all in one place. I appreciate the captions because I couldn't get the volume up enough for these old ears.
     
  6. Tobho Mott

    Tobho Mott Silver Banner Member

    Good point Pat, I'm still working my way through Campbell's 10 Rules book, but I don't have the bigger more expensiver one that I'm told 10 Rules is pretty much an excerpt from.

    Jeff
     
  7. ESC

    ESC Silver Banner Member

    If you watch the entire clip ironfarmer credits Campbell for his research.
     
  8. oldironfarmer

    oldironfarmer Silver Banner Member

    I think it's a bit of a stretch to say that by eliminating air entrainment in the sprue you have achieved nothing.

    And I still contend that the majority of home casters melt scrap thereby violating Dr. Campbell's first rule. There is a group making less than perfect castings who would still like to improve.
     
  9. PatJ

    PatJ Silver Banner Member

    Let me reprhase that.
    If you eliminate air entrainment, then you are 1/10 of the way towards a good casting.
    9 more to go.

    Edit:
    I am not knocking what you are doing, it is great research.
    What I am saying is that it is a 10 piece jigsaw puzzle, so don't forget the other 9 pieces that have to also fit.

    What I actually said was "if you pay attention to the bifilm theory and ignore John Campbells' 10 rules, then you most likely will have achieved nothing".
    I did not say "eliminating air entrainment in the sprue achieves nothing".
    The intent was that if you control air entrainment without controlling the other variables, you can still produce a bad casting.
    If the intent is to produce a good casting, then yes, you probably will achieve nothing if you ignore the other things.
    .
     
    Last edited: Jun 14, 2019
  10. oldironfarmer

    oldironfarmer Silver Banner Member

    Thanks, Pat.
     
    Last edited: Jun 14, 2019
  11. PatJ

    PatJ Silver Banner Member

  12. JCSalomon

    JCSalomon Copper

    You might look into the Mini Casting Handbook. Dr Campbell told me it has his latest research on the spin traps (mentioned but not worked out in the Complete Casting Handbook).

    Dunno why Amazon US doesn't carry it, but it's a bit less than $35 from Amazon UK or from the UK publishers directly to addresses here in the US—including shipping and currency exchange.
     
  13. Tobho Mott

    Tobho Mott Silver Banner Member

    Figured I'd check Canadian Amazon. Here's the first thing I saw:

    PhotoPictureResizer_190616_163151363_crop_1053x1665.jpg

    o_Oo_Oo_O

    Jeff
     
  14. Petee716

    Petee716 Silver Banner Member

    Well that's for the Canadian translated version. Maybe the US version will be cheaper.lol
     
  15. JCSalomon

    JCSalomon Copper

    £17.50 at https://amazon.co.uk/dp/1912078740; add another £6.94 for delivery to Norfolk, VA = £24.44; at Amazon’s exchange rate today of £1 = $1.32, that’s $32.23.
     

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