Bob Puhakka on Bifilm theory

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

  1. Jason

    Jason Gold

    Speaking of Bob... I noticed last night everything on his channel is gone. again.:rolleyes:
     
  2. Tobho Mott

    Tobho Mott Gold Banner Member

    The 3 long how-to-bifilm-for-the-home-gamer videos he made are still available on SwDweeb's youtube channel and not going away anytime soon, if anyone reading here is new and wants to see who we're talking about.

    Jeff
     
  3. DavidF

    DavidF Administrator Staff Member Banner Member

    That dude is a wack job.....
     
    HT1 and Melterskelter like this.
  4. HT1

    HT1 Gold Banner Member

    thats because he did not say anything that was not already Part of AFS , I learnt sprue Taper calculations in 1992 in the Navy's Journeyman school . fact though is you dont worry about it often in a Pro foundry, because sprue cutters arre made to the proper taper and are Laying about


    V/r HT1
     
  5. Tobho Mott

    Tobho Mott Gold Banner Member

    He also showed off his sparkling personality... o_O
     
    dtsh likes this.
  6. Billy Elmore

    Billy Elmore Silver

    Wow! There is a lot of information in this huge ass post.LOL I had lots to say about the whole design aspect and Campbells methods and theories but decided not to bore anyone with all the little details and just say that it is not as complicated as they make it. Sand is the biggest enemy of cast iron and unless you have just an awful completely shitty gating design than sand is probably what causes your inclusions.
     
  7. JCSalomon

    JCSalomon Copper

    All I recall from the Complete Casting Handbook is that CI is a little different to other metals in this regard, details not specified. (I have heard the Mini Casting Handbook has discussion of and tips for CI, but I have not read it yet.)

    Is cast iron that much more forgiving than aluminum regarding entrained oxides? Are there aspects of the general Campbellian guidelines that are inappropriate or overkill for CI?
     
  8. JoeC

    JoeC Copper



    Cast Iron has a separate phase of flakes of graphite (carbon)

    These flakes are similar in strength to pencil "leads"

    So oxide films although bad won't make cast iron much weaker

    That is why cast is so brittle and hard to weld

    For ductile iron however, properties can absolutely be improved with "the methods"

    Now don't forget, Dr Campbell and Bob are working with "engineering" castings where every small improvement in strength can let the designer reduce section size and save weight. Important for automotive, aerospace, safety critical castings, etc.

    For "commercial castings" that don't need to carry loads and where failure doesn't cause death, "the methods" are not just overkill but Mad Max level overkill

    As this forum proves you can melt beer cans and pour them into an anthill and get a fantastic looking shape

    You can top pour down an open riser with no gating at all and get a shape

    And that is great, the MacGyver git er done spirit built America, I love seeing people just go ahead and make things

    The people reading this thread are actually ahead of 95% of the commercial industry in deep foundry understanding (IMHO)

    The work with the glass plate allowing a view of filling is easily at a Masters degree level

    Bob & Dr Campbell are going through a Galileo vs Catholic Church phase right now, it will take decades to sort itself out

    Way Off Thread

    I have a new project that is taking up most of my time now, I plan to cast some custom Aluminum valve covers for it, will post a thread if Covid doesn't get me first!

    She is a rare (but not valuable) bird, let the guesses begin!

    Annoying the Neighbors.JPG
     
  9. Gippeto

    Gippeto Silver

    Lookin like a Bricklin to me...used to see the odd one in the Auto Trader way back...along with a Delorian or two....and $50 Honda Civics/VW Bugs lol.

    Al
     
  10. rocco

    rocco Silver

    That's an easy one, it's a Bricklyn!
     
  11. Billy Elmore

    Billy Elmore Silver

    It's pretty forgiving in regards to oxides especially when compared to other metals. If you go the extra step in cleaning your iron before pouring and have a good mold with a depressurized gating system your chances of having a good casting are pretty high. In my experience the velocity of iron is a factor more about erosion than oxides. I'm sure there are many who can relate and or disagree.
     
  12. Jason

    Jason Gold

    OMG man, what the hell are you doing with a bricklin? Watch how much you dump into that thing, you can get a real nice one for around 15k. It's real easy to lose your ass on them. Malcolm was the cowboy with the boots (YUGO) while John Zachery Delorean had the $1000 suits. Two guys, more charisma than brains, both produced very unique and shitty automobiles. Why is it with the exception of the SL mercedes, EVERYTHING with gullwing doors suck? If you want weird, even an Opel would be a better investment. Not saying much I know.

    John-DeLorean-and-Malcolm-Bricklin-at-auto-congress-DeLBricklin-failed-10-768x960.jpg

    Here is another 1st class shitbox! Slow (105kts), french, parts were overpriced, hard to get and was the most useless boutique airplane ever built!
    We had one for awhile. It rightly earned the nickname as "The Tampon!" Stupid gullwing doors leaked bad even with new seals and
    would fill up the seat pans with water.:rolleyes: Then on a windy day, turn the thing the wrong way on the ground, catch a gust of wind and it's goodbye about 2grand
    to fix the stupid door. I suppose that was better than LOSING fingers if you had them resting on the sill.:rolleyes:
    The brits love 'em. I'll never understand why. Cheap on gas probably helps. Eccentric types like oddball stuff.

    Socata Tampico.

    139867.jpg
     
  13. Peedee

    Peedee Silver

    Jason, I really wish you would stop holding out on your feelings and tell us what you really think. I'd suggest a counselor from over here but he flies a Piper and drives an E type, both of which won't make the trip for a home visit ;) (I'm pulling your leg before the internest police come after me)

    I know nothing about a Bricklin, I'm guessing it's a re-badge import, should do my homework

    Edit: My apologies, I thought it looked liked a Midas.
     
  14. Jason

    Jason Gold

    lol peedee.. The bricklin was built in canada. It had a short and miserable life. To say it was not well received by the public is an understatement. Just like the Delorean. Only reason people know what that POS was came from the movies. Of all people, any middle aged brit should know what an absolute crime that was for the UK. Let's see, an american man uses queen money to build a heavy sports car in Ireland with a 130hp french motor sporting a citroen drivetrain. No thanks.
    He was a good salesman, but that's about it.

    Back in the 1980s, Aicraft manufacturers were getting the pants sued off them for aircraft they built 40years ago. Subsequently, the big ones like Cessna and Piper gave the public the middle finger and the quit making small airplanes. Who could blame them? Well, I was at Embry Riddle back then and what brand new fleet of airplanes show up; The mighty TAMPON! ERAU needed new aircraft and the only ones stupid enough to build little airplanes was Socata. When my buddy bought one, I begged him not to, but he was smarter than me, I guess, and for over 600hrs I got the pleasure to experience that miserable fishbowl. In its defense, it flew like a diamond. All push/pull rods and it only took 2 fingers to make it do what you want. It was everything else about it made it completely shitty.
     
  15. Peedee

    Peedee Silver

    I know of no Brits that would touch a delorean without first contemplating jumping off a cliff, the bricklin is a new on me. But we are all individuals.

    I quite liked the Piper Aztec twin (from what little I know of aviation) but this is as far removed from bifilm theory as we could get so I ought to let the thread go back on track.
     
    Jason likes this.
  16. Jason

    Jason Gold

    lol.. smart brits.
     
  17. M35-1

    M35-1 Copper


    Good thread here!

    Purging gas doesn't work as its almost impossible to get the oxygen content low enough to prevent oxide film formation. Therefore any splashing in the mould will undo any good work that has gone on before.
     
  18. M35-1

    M35-1 Copper


    This is a poor paper. Prof Campbell has actually written in to suggest why they didn't get the expected results. He thinks the quality of the melt was poor, so it didn't matter how they poured it, it was always doomed to fail.

    Does anyone on this thread have tensile testing done of alloys they have poured using naturally pressurised running systems?
     
    Tobho Mott likes this.
  19. M35-1

    M35-1 Copper

    This was cast with as near as we could get to a full naturally pressurised running system. Material is duplex stainless steel, poured at 1530°C approx 3000kg in the ladle . DPI crack detection performed with excellent results.

    If you're chasing quality, Campbell's way is best.

    DSC_2019~2.JPG
     
    Tobho Mott likes this.
  20. Jason

    Jason Gold

    Unless you are melting with electricity or induction.... But, I agree, in a fuel fired furnace, it does present some real problems.
     

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