Making a sand core

Discussion in 'Sand Casting' started by Chazza, Apr 5, 2020.

  1. Chazza

    Chazza Silver

    There is a danger here, of telling Granma how to suck-eggs, but in case anyone hasn't heard of this recipe, it works very well.

    Ingredients

    • Calculate the amount of dry sand needed for the project. Easy to do by pouring it into the core-box and weighing the sand, plus a bit extra.
    • Use molasses as the binder; quantity is 2% by weight of the sand.
    • Water to dampen the mix at 1% by weight.
    • Corn flour – also called corn starch – at 2% by weight

    Recipe
    1. To the dry sand, add the flour and mix thoroughly by hand. I did mine in an old saucepan but on a flat smooth bench top, would work just as well.
    2. Weigh the molasses in a paper cup and pour and scrape it, into a clean used plastic bottle with lid. I used a milk bottle and the paper cup to save on cleaning it.
    3. Weigh some warm water and add it to the molasses and mix the ingredients by shaking the bottle. So the mix will be 1:1 molasses and water. I deliberately mixed more than I needed, so that I had some mixed for next time. Hot water makes mixing so much easier.
    4. Add the water and molasses solution to the dry ingredients and mix thoroughly.
    5. Pack and ram the sand into the core box. I dusted the core-box with parting powder first.
    6. Place a flat plate on top of the core-box, invert and place on the bench. Rap the core-box lightly and remove.
    7. Bake core in oven at 160 C. My core was about 10" x 8" x 6" and I needed to bake it for 2 hours.
    The core produced was very hard and handled well and could be removed with a hammer, from an aluminium casting. I did try another one at 1% molasses but the surface was friable.

    Mixing with molasses undiluted worked, but resulted in a spotty core and I couldn't see the point in not making it mix more thoroughly.

    Smells nice when cooking as well, unlike the linseed experiment, which nearly caused a divorce,

    Cheers Charlie
     
  2. Chazza

    Chazza Silver

    Whoops, typo on item number 3. The molasses mix should read 2:1.
     
    Melterskelter likes this.

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