sand casting brass

Discussion in 'Sand Casting' started by savarin, Mar 10, 2023.

  1. Melterskelter

    Melterskelter Gold Banner Member

    To try to deteermine a measured amount of wetness to compare to someon else's sand or to a source like the Navy Foundry Manual, it might be interesting and inforamtive to weigh out a pound or two of sand and then bake it dry and then rewigh it dry so you can have an % idea of where you are.

    Denis
     
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  2. savarin

    savarin Copper

    The lead end of the hammer has a 12mm bolt screwed into the central part with about 15mm standing up.
    I wrapped the central part in a thin sheet of tin, heated it up then held the lead ingot over the opening letting it melt into the resulting cylinder.
    These are the two brass casts machined down, I think they look pretty good.
    hand-wheel-1.jpg
    hand-wheel-2.jpg




    but



    this is the inside, still enough metal left so I am using them. Hopefully better result next time.
    hand-wheel-3.jpg
     
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  3. Ironsides

    Ironsides Silver

    There are two reasons preventing that from happening.

    1. The specific gravity of chromium is 7.1 and brass is about 8.5 so as the brass melts the chromium will float to the top with the powdery dross and have no contact with the molten brass.

    2. Exposing less than paper thin chromium plating in a fuel fired furnace it will oxidize, even more so when it floats on the top exposed to the furnace atmosphere.
     
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  4. Melterskelter

    Melterskelter Gold Banner Member

    I did some checking around for information on melting chromed brass parts and confirmed Ironsides' predictions above.

    Denis
     
    Last edited: Apr 11, 2023
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  5. savarin

    savarin Copper

    If I want to cast brass round or square stock what is the best way, vertical or on their sides and how to add risers so they dont shrink.
     

  6. That is a subject of lots of earlier speculation here, I've made some vertical cast bars and hollow shrink defects take up about half the bar length: https://forums.thehomefoundry.org/i...-brass-today-from-scrap-zinc-and-copper.1882/. I was boring the bar so it wasn't much of a problem. The only feedback I have from a guy who cast tonnes of bronze and brass bar was to either cast it hollow or cast it with the expectation that about 40% will have to be remelted and cast again later (grip that end of the bar in the lathe chuck). Some other members say they cast their bars horizontally and get good results, though I don't know if that's with brass.
     
  7. Tobho Mott

    Tobho Mott Gold Banner Member

    Maybe more than you wanted to know about ramming up billets suitable for machining etc.:



    Good luck!

    Jeff
     
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  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    2hrs+ for ramming up casting billets? I like Sandrammer's channel but maybe someone would like to post up the Cliff notes version ;)

    Best,
    Kelly
     
  9. Melterskelter

    Melterskelter Gold Banner Member

    I agree on the summary idea. I simply could not bring myself to watch a 2 hr video to try to extract the pertinent 5 mins of information.

    Denis
     
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  10. HT1

    HT1 Gold Banner Member

    Billet or round stock??? Billet has a hole in it
    cast them upright with an open top you dont need a cope , but you cannot pour directly into the mold cavity you have to use a tapered sprue to a gating system which can be very simple , if you are making ring billet you can use a green sand core , for smaller holes a core with just a core print on the bottom , and some core wire (baling wire ) to anchor the top of the core from moving side to side is perfect

    increase the Height of your billet or stock to act as it's own riser , if you taper the top opening it up like a funnel you will get more solid metal and less riser the exact amount depends on your alloy ( the tapered out area acts as a heat sink allowing the metal to feed longer) you can also hot top billet, that means after you have pourn the part you intend to use, you can switch an begin pouring hot metal directly into your Riser this puts the hottest metal where the most heat is needed to prevent premature freezing , promoting longer feeding .

    there is also commercial exothermic hot topping compounds literally Thermite you can use to add to the top of your "riser" to promote longer feeding , Be forewarned these compounds Screw with the alloy at the top of the riser so it must be completely scrapped out not remelted if you have alloy concerns


    V/r HT1
     
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