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Made my own cast alloy nailhead valve covers

Discussion in 'The Hokey Ass Message Board' started by Carb-Otto, Nov 15, 2006.

  1. bastadical
    Joined: Sep 6, 2006
    Posts: 155

    bastadical
    Member
    from Fenton, MI

    Why don't you go ahead and do a valley cover too and then I can order the complete set for my 322...

    Awesome work, btw. Makes me wish I was a little more talented and a little less lazy.
     
  2. According to Dave Gingery's book, 1/4" per foot for aluminum. Here's a pdf, if it doesn't work P.M. me and I'll send a hard copy.
    View attachment ALUMINUM SCALE.pdf
     
  3. Dirty2
    Joined: Jun 13, 2004
    Posts: 8,903

    Dirty2
    Member

    Very Very nice.
     
  4. 1oldtimer
    Joined: Aug 21, 2003
    Posts: 7,675

    1oldtimer
    ALLIANCE MEMBER

    yes they do and they're EXPENSIVE. i went to 5 different ones and got quotes from $15k to $30k to do a run a 1000 ( in investment casting). i was thinking to do sbc, nailhead, 348 and buick straight 8 but too much $$$ for me. the computer one was a joke not what it was really going to look like, i just could'nt find the other picture on my computer.
     

    Attached Files:

  5. Mojo
    Joined: Jul 23, 2002
    Posts: 1,858

    Mojo
    Member

    Wonder if lost wax and lost foam method would work too? Basically, you make the part out of wax. Then make the mold, pour the aluminum. The aluminum melts the wax out and fills in the void. Syrofoam works too, I was reading about it the other day actually.
     
  6. how much for aset thats what i want to know
     
  7. Nice job.
    When i did my manifold lid I discovered there are hundreds of small foundries around that i never knew about. i am sure there are more in the US. All you have to do is ask. Even a quck search of the internet will give a few in a hurry.
    That sure is a beautiful valve cover
     
  8. The pictures I've seen indicate that the finish isn't very good, and would require A LOT more work before polishing.
     
  9. 1oldtimer
    Joined: Aug 21, 2003
    Posts: 7,675

    1oldtimer
    ALLIANCE MEMBER

    investment casting = lost wax
     
  10. 1oldtimer
    Joined: Aug 21, 2003
    Posts: 7,675

    1oldtimer
    ALLIANCE MEMBER

    there's more clean-up work with sand casting then with investment casting (that's why most finned covers aren't smooth between the fins). investment casting is like what they make rings with (not the engine one's, the one's you buy your girlfriend).
     
  11. attitudor
    Joined: Sep 28, 2004
    Posts: 2,975

    attitudor
    Member
    from Finland

    Bumb for the tech week.
     
  12. ddkarmann
    Joined: Nov 15, 2006
    Posts: 5

    ddkarmann
    Member
    from indiana

    i have some new nailhead parts too , how do i post pictures?
     
  13. zman
    Joined: Apr 2, 2001
    Posts: 16,555

    zman
    ALLIANCE MEMBER
    from Garner, NC


    Start out with...
    Read This First!
    You should have seen it when you signed up...
    It'll explain all about doing an intro in the proper section and then post away. You can either upload the pics here as attachments or host them elsehwere (like imageshack or flickr). I'd start a new thread for it as well. No need to add on to a Tech Week post....
     
  14. Just so I am thinking correctly... If the aluminum shrinks 1/4 of an inch per foot, the mold needs to be 2.08% of 1.208 times bigger than the desired final product.

    Is the 1/4 inch per foot universal for most alloys and a good enough number to use for getting a fit presice enough for proper gasket seating?

    Thanks,
    Geno
     
  15. Rusty
    Joined: Mar 4, 2004
    Posts: 9,449

    Rusty
    Member

    Too Cool!!! Metal takes patience but sanding wood is double. Very, very nice work.
     
  16. LOWCAB
    Joined: Aug 21, 2006
    Posts: 1,989

    LOWCAB
    Member
    from Houston

    Metal shrinks as it cools. Therefore, a casting is larger when it is hot than after it cools. When making a die, the diemaker has to make the die slightly larger than the finished casting.. The amount of shrinkage depends upon the type of metal being cast, and on the whether the mold will cool quickly or slowly. For small castings, the shrinkage rate is:

    Iron - 1/8" per foot
    Steel - 1/4" per foot
    Aluminum - 5/32" per foot
    Brass - 3/16" per foot

    BR
     
  17. I don't know if your math is accurate, but according to my book, 1/4" per foot. If you PM your address and send me a few stamps, I'll send you a paper ruler you can varnish to a paint stick.

    I don't know the shrinkage of other metals.
     
  18. roddinron
    Joined: May 24, 2006
    Posts: 2,677

    roddinron
    Member

    It's also used in the dental lab industry (it's what I do) to cast crown and bridge and partials. Lost wax and investment along with spin casting results in a very precise casting. A spin caster big enough to do valve covers would be VERY expensive, but would result in nice dense castings that would contain very little porosity and polish beautifully.
     
  19. Wow, that's a awesome looking valve cover Carb-Otto

    If you have any extras that you plan on selling, I'll buy a pair for (insert drum roll) my 59 Buick wagon.

    Scootermcad - thanks for the kind words.

    JimV - I believe that Cumberland Foundry is a ferrous foundry - i.e. cast iron vs. aluminum/brass/bronze.

    The angle that you need on the pattern (which is what the foundry types call the master that you make the mold from) is called the "draft angle" and I use 3-4 degrees as a rule.

    And as for shrinkage, I use .013" (thirteen thousands) per inch for my aluminum patterns. So that works out to .156" per foot which is suspiciously close to 5/32" per foot.

    Dennis
     
  20. Bugman
    Joined: Nov 17, 2001
    Posts: 3,483

    Bugman
    Member

    I really like this one. I'm planning on doing some casting in the near future and will probably use this technique, although with a CNC machined block of hardwood as my pattern since i have almost zero woodworking skills. The CNC makes it easy to scale up to ciompensate for shrinkage as well.
     
  21. 3034
    Joined: Nov 18, 2005
    Posts: 441

    3034
    Member

    Wow! Nice work!
     
  22. TagMan
    Joined: Dec 12, 2002
    Posts: 6,068

    TagMan
    ALLIANCE MEMBER

    Absolutely awesome !!

    If you decide to make these up to sell, count me in for a set for my 401.
     
  23. I just read this thread, and WOW! do those valve covers look beautiful.

    There's been a lot of talk about shrink factors; there are special rulers ('shrink rules') that pattern makers use. Google "shrink rule" (keep the quotes) or click here. Easiest way to go, but you can also just add 1/8" or 3/16" per foot (depending on what kinda' metal you want to cast).

    Also, about WA foundries; there's a little one I saw between 1st & 2nd ave south of the ball parks (in Seattle); somewhere near the Sears store. There's also a big one (olympic?) on airport way near lucille street. And I think there may be one or 2 more here in town.

    -bill
     
  24. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,964

    Shifty Shifterton
    Member

    Couple other tips from a foundryman

    Try to make the walls somewhat uniform. Any thick areas will require a riser or gating to prevent shrinkage defects upon solidification. Example, if the rails and ribs on this valve cover would have been doubled in thickness, would have presented an issue as they're on opposite ends of the casting, and both need fed by a gate or riser. Common problem area is anyplace you put a mounting boss, those tend to be thick.

    Make your wood pattern somewhat durable, in order to pack the sand around the buck, there's some force involved.

    Shoot for one flat side with all the draft angle coming off the flat. The pattern will be mounted to plywood or other flat sheet to make the mold. If there's no flat, then it will have to be sliced, mounted on BOTH sides of the plywood and have draft accordingly. It is possible to do loose piece molding without mounting the pattern but you're asking for a higher price, lower yield, and more flash on the finished piece.

    The best thing I could recommend is to visit the foundry with something similar in hand. They will clue you into the blind spots. I make a decent living trying to undo what not-foundry-smart design engineers have done.

    Good Luck, and don't be afraid to try. If you can build a hot rod, you can make castings. But be patient, it's as much an art as a science.

    Edit- almost forgot, nice craftsmanship man!
     
  25. Rand Man
    Joined: Aug 23, 2004
    Posts: 3,572

    Rand Man
    Member

    Very nice. My Grandfather was a pattern maker. He had several special measuring tools. Calipers, mics and such scaled for each metal. I wish I would have learned the trade.
     
  26. Skate Fink
    Joined: Jul 31, 2001
    Posts: 3,472

    Skate Fink
    Member Emeritus

  27. Burny
    Joined: Dec 20, 2004
    Posts: 1,600

    Burny
    Member

    Awesome post! Beautiful work...

    Hey, Like El Coolmino said, you have to mount on flat surface...I'm wondering how you get the hollowed out inside using sand casting?
     
  28. Broman
    Joined: Jan 31, 2002
    Posts: 1,484

    Broman
    Member
    from The Island

    Holy Crap

    BTTT


    I haven't been this horned-up by a post since WhizzerRick made the famous HAMB 'plate toppers....

    What is it about forging steel that makes us all quivver with delight?

    Goddamn that's cool. I have been wondering what it would take to do some of this stuff for a long time....I just wish I had the spare time/money to foray into the void and create something that cool.

    Hats off my friend...
     
  29. Spend $16 bucks on this guy's books.
    http://www.backyardmetalcasting.com/
    Then diceide if you want to spend about $30 (or find old stuff for free) on a small metal trash can, a big flower pot, and a bag of concrete.
     

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