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How to achieve a cast finish?

Discussion in 'The Hokey Ass Message Board' started by No_Respect, Feb 2, 2011.

  1. No_Respect
    Joined: Jul 27, 2005
    Posts: 1,169

    No_Respect
    Member
    from So-Cal

    I have a bunch of billet machined parts that were one off made. I do not want to polish these parts is there a way to achieve a cast look on these?
     
  2. Da Tinman
    Joined: Dec 29, 2005
    Posts: 4,226

    Da Tinman
    Member

    Last edited: Feb 2, 2011
  3. shane85
    Joined: Nov 30, 2005
    Posts: 257

    shane85
    Member

    glass bead media.
     

  4. Deuces
    Joined: Nov 3, 2009
    Posts: 18,539

    Deuces
    Member
    from Michigan

    Nope! Bird shot!
     
  5. No_Respect
    Joined: Jul 27, 2005
    Posts: 1,169

    No_Respect
    Member
    from So-Cal

    Wow thanks guys! I was told that Media wont work so I guess I'll try it out!
     
  6. fiveohnick2932
    Joined: Mar 29, 2006
    Posts: 889

    fiveohnick2932
    Member
    from Napa, Ca.

    File edges, shot peen then sand blast.
     
  7. Da Tinman
    Joined: Dec 29, 2005
    Posts: 4,226

    Da Tinman
    Member

    actually heavy grit sand works much better, tried both and sand is much more convincing.
     
  8. Crafty B
    Joined: Oct 26, 2006
    Posts: 407

    Crafty B
    Member

    steel shot in a sandblast cabinet then lightly scotchbrite...I do it everyday
    CB
     
    61klassic likes this.
  9. treb11
    Joined: Jan 21, 2006
    Posts: 3,542

    treb11
    ALLIANCE MEMBER

    the bigger the grit, the rougher the fiinish will be. So skip the glass beads and go straight for playground sand
     
  10. handyandy289
    Joined: Sep 19, 2010
    Posts: 354

    handyandy289
    Member
    from Georgia

    Try a pneumatic de-scaler. the one with a bunch of rods for chipping scale or rust.
     
  11. yekoms
    Joined: Jan 21, 2007
    Posts: 1,088

    yekoms
    Member

    I'm a cylinder head guy in a race engine shop. Garnet media in a blaster works great for making machined steel or cast iron look as cast. On softer metals back blaster nozzle away from part. If you want a section of your part to not get texured tape it off with heavy rubber tape. The tape that powder coaters use should work. Duct tape just gets shredded to a gooey mess. You can even file in small grooves to make fake casting seams.
    On soft metals sand like Da Tinman said works good.
    Smokey
     
  12. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    CutawayAl
    Member
    from MI

    A needle scaler works, but it's slow, tedious, and requires some practice/skill to get a good result. I found you get a better look by contouring all the needles to look like a sharpened pencil, but with the points radiused round. At the same time, all the needles should be kept the same length. Over time, and depending on the material of the parts, the needles will require re-radiusing.

    Blasting with sand, grit, etc. will produce a rough satin finish, but careful blasting with appropriate sized shot or large diameter glass beads(on aluminum) produces a finish more like a casting.

    Be aware that overly heavy blasting imparts a lot of stress into the part. That can cause distortion, and even break small parts. To avoid problems, especially on thin/delicate parts; all you want to do is alter the surface using as little pressure as possible/practical, nothing more.

    Whether blasting or needling is done, on aluminum I have found that a light final finishing with fine Scotch-Brite and phosphoric acid(Alumi-Prep or aluminum cleaner) rounds off the worst of the surface roughness, giving a nicer finish that is easier to keep clean and less susceptible to fingerprints etc.
     
  13. pecker head
    Joined: Nov 8, 2006
    Posts: 3,752

    pecker head
    Member

    What is the differents between machined aluminum & billet ?
     
  14. Skirv
    Joined: Jul 5, 2006
    Posts: 1,183

    Skirv
    Member

    I did this to a few parts including this water neck. I softened the sharp edges with a grinder, went over the parts with a needle scaler, then sand blasted.

    [​IMG]


    [​IMG]

    [​IMG]
     
  15. The word billet is used incorrectly most of the time.
     
  16. pecker head
    Joined: Nov 8, 2006
    Posts: 3,752

    pecker head
    Member

  17. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    CutawayAl
    Member
    from MI

    The definition varies a little from one field to another. Foundries call rough poured blocks of metal billets. The forging industry calls raw forgings billets. In the hot rod crowd, in the minds of most, billet is the fully machined, machined from solid look. In the automotive world, a forging is a forging, a casting is a casting, and a billet part is one machined from a solid chunk(billet) of material. For example, billet gears, crankshafts, connecting rods, and cylinder blocks are carved/machined from a solid block of raw material. Although a casting can be fully machined to look like a billet part, in automotive terms it really isn't billet, it is a fully machined casting.
     
  18. pecker head
    Joined: Nov 8, 2006
    Posts: 3,752

    pecker head
    Member

  19. No_Respect
    Joined: Jul 27, 2005
    Posts: 1,169

    No_Respect
    Member
    from So-Cal

    Lots of good info here I have a modern billet Aluminum head that I want to make look like its cast and the intake which was custom machined for me. I just want to make the modern engine look like it was stock from the 1960's
     
  20. chopolds
    Joined: Oct 22, 2001
    Posts: 5,804

    chopolds
    Member
    from howell, nj
    1. Kustom Painters

    If doing just some touch up on freshly machined, or welded sections of a cast part, I just grab a piece of sandpaper, and hammer some texture into the surface. You can vary the roughness with different grits!
     
  21. Deuces
    Joined: Nov 3, 2009
    Posts: 18,539

    Deuces
    Member
    from Michigan

  22. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,335

    scootermcrad
    ALLIANCE MEMBER

    Was just thinking about this very topic...

    Now THAT is an interesting approach! Probably works well on aluminum...
     
  23. RHOPPER
    Joined: Mar 12, 2006
    Posts: 263

    RHOPPER
    Member

    Round the edges and spray with hammertone paint?
     
  24. von Dyck
    Joined: Apr 12, 2007
    Posts: 678

    von Dyck
    Member

    Well, if you are going to paint the part, after correct prepping, spray on your "tack" coat. Sprinkle some clean sand (your choice of grit) and follow up with subsequent coats for complete coverage. Works great where a cast iron or aluminum repair was made and the part was originally painted.
     
  25. Da Tinman
    Joined: Dec 29, 2005
    Posts: 4,226

    Da Tinman
    Member

    Fresh out of the blast cabinet, sprayed with flat clear. Knocked most of the street rod right out of it, they was brushed when I got em.


    [​IMG]

    makes them almost invisible when installed. I made new brackets to mount them upright and those arent the correct screws.

    [​IMG]
     
  26. Larry T
    Joined: Nov 24, 2004
    Posts: 7,660

    Larry T
    Member

  27. jcs64
    Joined: Apr 25, 2005
    Posts: 528

    jcs64
    Member

    these started off as 6.5" dia. carbon bar stock Before I machined them.
    Just grind and file all the sharp corners (irregularly makes for a more casted look), Then media blast. I used glass, but a coarser sand would have worked better
    Jeff
    [​IMG]
     
  28. xlr8
    Joined: Jun 26, 2006
    Posts: 650

    xlr8
    Member
    from Idaho

    Eastwood and some of the other restoration suppliers make a paint that gives the cast look.
     

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