Flying skull hood ornament

Discussion in 'Investment casting Ceramic shell method' started by DavidF, Apr 15, 2019.

  1. DavidF

    DavidF Administrator Staff Member Banner Member

    Started on making up some hood ornaments for a customer who carved the master pattern from a chunk of Corian. The mold is done and I'm pouring the waxes now. Will still be another week or so before I pour. Here is a picture of the first wax...
    20190410_122626.jpg
     
    Jason and Tobho Mott like this.
  2. Tobho Mott

    Tobho Mott Silver Banner Member

    Hey, that's gonna look pretty cool! What metal does he want it cast in?

    Jeff
     
  3. DavidF

    DavidF Administrator Staff Member Banner Member

    Just aluminum...
     
  4. PatJ

    PatJ Silver Banner Member

    That's pretty neat.
    I think stuff like that goes from some good money at the car shows.
    .
     
  5. Jason

    Jason Gold Banner Member

  6. DavidF

    DavidF Administrator Staff Member Banner Member

    Yes you can chrome plate aluminum, it just requires one more step in the process prior to the cyanide copper strike.
    The original ones were not plated, and this whole thing is about traditional hot rodding so plain old aluminum it is.....
     
  7. Jason

    Jason Gold Banner Member

    If it was my rat rod, it'd be bronze. I'd polish his teeth and leave the rest flat.:D
     
  8. PatJ

    PatJ Silver Banner Member

    You could always anodize it.
    Apparently you can get a variety of colors and finishes.
     
  9. DavidF

    DavidF Administrator Staff Member Banner Member

    Cast aluminum does not anodize well due to the silicon content. They do make a special dye for cast, but as far as I know it only comes in black.
    These were originally polished, but I'm just pouring the castings....Well, I am making one for myself. I'll polish it....
     
  10. PatJ

    PatJ Silver Banner Member

    You could polish it and clear coat it.
     
  11. I've successfully anodized cast aluminium alloys with silicon, if you bead blast the surface or work it over with a wire wheel it then seems to anodize well. Probably the silicon gets removed from the surface by doing so, I was anodizing sand cast 90 degree elbows used to fabricate intake manifolds so there was no fine detail. A dip in a 20% nitric acid solution after polishing will brighten/whiten the aluminium and establish a thin uniform oxide layer as nitric is an oxidizing acid, you have to do that as the final treatment before anodizing (de-smutting).
     
  12. DavidF

    DavidF Administrator Staff Member Banner Member

    Finally getting back to casting. A couple more layers to go, then into the burn out kiln...
    20191107_080020.jpg
     
    Tobho Mott likes this.
  13. Jason

    Jason Gold Banner Member

    Rock on! Over sprued the hell outta that huh? We must be related.
     
  14. DavidF

    DavidF Administrator Staff Member Banner Member

    Have a bit of a shell cracking issue. Waiting for things to cool down so I can patch them up...
    20191109_145923.jpg
     
  15. Jason

    Jason Gold Banner Member

    ugh..
     
  16. DavidF

    DavidF Administrator Staff Member Banner Member

    Ok, so after I patch these guys up, and add a couple more layers of shell I guess I have to re fire them?? Will they crack again?? Ive been lucky so far and haven't had to patch things up before...
     
  17. Jason

    Jason Gold Banner Member

    No it won't crack again. You don't have to do a separate refire.. Just heat them up as usual before pouring in your metal. I think you only have to go over 700f.

    Remember, you cracked because of the expansion of wax.
     
  18. DavidF

    DavidF Administrator Staff Member Banner Member

    Poured...
    Came out pretty good considering everything that could go wrong did go wrong...
    Oh well on to sanding and polishing...
    20191112_125811.jpg
     
  19. Jason

    Jason Gold Banner Member

    He's cool. Send me a wax, I'd like to do one in bronze.
     
  20. DavidF

    DavidF Administrator Staff Member Banner Member

    No can do... it's a customers design...
     

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