Thursday, 31 March 2011

CASTING METAL LETTERS

For some years now my older brother Stephen has had his own foundry, called Whitton Castings in Charlton. A few days ago he took me through the process of making some letters out of lead. We used lead because it was the  easiest metal to melt in the time available. The same process is used if you wanted to make the letters in aluminium, brass or bronze. Below are the results with a brief description of the process involved.

STEP ONE: You start of with a molding box and the letters you are going to copy. The letters here are some of my own which are make of wood and sprayed silver.

STEP TWO: You then sprinkle parting powder over the letters. This stops the letters sticking to the sand. You could use talcom powder but parting powder is far better. The letters are then covered in a layer of sieved red sand, which is fine and smooth sand and makes for good better finish.
STEP THREE: The red sand is pressed tightly round the letters to stop them moving. Then black sand is sieved and fills the molding box. This is then pressed firmly into the box. More sand is added and pounded so it is tight and firm. A bit like making a sand castle at the beach is the best way to describe it.
STEP FOUR: The Sand is then leveled off, so you have a flat surface. The molding box is then turned over and placed down again. The other half of the molding box is then placed on top. A small piece of wood is place just above the letters, this makes a sort of tunnel for the molten metal to pass through. More parting powder is sprinkled over.
STEP FIVE: Using a metal pipe to press a hole to half way down until you touch the wooden block. Separate the two parts of the molding box and carefully remove wooden block, add more powder.


STEP SIX: Turn top half of box over and increase the size of the top of the  hole. This where the metal will be poured in. Add more powder round the hole.
STEP SEVEN: Now returning to the bottom of the molding box very carefully remove the letters. Using a sharp toll and small hammer to gently tap the letters free.
STEP EIGHT: Add more powder. Then with a small trowel cut small channels into the sand. This is how the metal will flow into the mold. Put both halves of the mold together. You are now ready for the metal to be poured in.
STEP NINE: The metal is melted in a furnace. The molten lead is now poured into the mold with a ladle until the molten metal pours out the top.
STEP TEN: When the metal has cooled down the mold can be separated to reveal the shinning metal letters.
STEP ELEVEN: The lead letters then have the excess metal trimmed off them and then smoothed to remove sharp edges.

The new metal letters placed next to the originals.


6 comments:

  1. Now we know what Steve does......but you don't seem to have a section on the sand throwing we also hear about!

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  2. Tim, do you know if your brother's foundry is able to / suitable for making an embossing plate? I'm looking to get a logo made up so that I can emboss / deboss book covers in bookbinding.
    Any ideas?

    PS your E's were very punny

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  3. Great post, Your letters turned out very well. I like your sand casting photos very informative. well done ;-)

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  4. Well done – it makes a nice change to read something that makes sense. Pleasing on the eye too. You have a real nice site! casting metal

    ReplyDelete