Hollowed out cannon balls; how did they make them?

Discussion in 'Cannon' started by Col. Batguano, Nov 10, 2017.

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  1. Nov 10, 2017 #1

    Col. Batguano

    Col. Batguano

    Col. Batguano

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    Just thinking about this a little bit. In the revolutionary period days, fused shells came in to use for artillery. The problem would be, how to make them?

    In the winter time here in the north country we make hollow ice globes with water balloons. Fill them with water, place outside, and an appropriate wait later bring the balloon inside. The water on the outside of the balloon has frozen, but the inside is still liquid. It's a small matter to just drill a hole through the balloon and ice through to the core and drain out the water that remains. You then have your hollow ice globe.

    Would hollowed out cannon ball shells have been made in a similar fashion? Cast the molten iron, and then take the mould apart while the interior metal is still molten, and drain it away?. The hole could then be threaded for a fused plug.
     
  2. Nov 10, 2017 #2

    csitas

    csitas

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    Col. I'm no expert here but I'm thinking they might have used a process called "slag casting". It worked much like what you describe. This took some practice. They would only file a ball mold just so full of molten metal. Then the casters would shake the ball mold so as to make the rest of the molton metal go to the outside of the mold,thus cooling it quickly. You would now have a hollow ball. Imagine the arms on those guys ,eh?
     
  3. Nov 10, 2017 #3

    Col. Batguano

    Col. Batguano

    Col. Batguano

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    Oh I get it. They would cast it with a plug in the middle much like cannon barrels were made or cast. The plug would be made out of hardened sand or clay that could be busted apart and "drained" out the hole once the whole thing was cooled. The sprue out the other side could then just be cut off and filed away.

    That makes much more sense and offers better quality control than the "ice globe" method.
     
  4. Nov 10, 2017 #4

    csitas

    csitas

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    Col. I didn't explain very well. Just google "slag casting". Maybe you'll get a better understanding of the process.
     
  5. Nov 11, 2017 #5

    Wes/Tex

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    I understood it was done with clay or sand spheres which were knocked apart and then out through the cut open vent. I'm no expert but that's what I remember someone explaining once. Standard "shells" for howitzers were filled with powder but "cased spherical shot" or "shrapnel" had musket balls mixed with the powder for more fling chunks. The secret to both was a guy who knew how short to cut the fuses so they'd go off 20 or so feet above the ground.
     
  6. Nov 11, 2017 #6

    Zonie

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    Simple sand castings may have been used to make the hollow cannonballs.

    Without going into the fine points, to make a sand casting of a solid ball you would have a wooden ball and would bury it half way into the sand in an open top box. (The box would be full with the wooden ball sticking half way out of the sand.)
    (This lower box is called a "drag".)

    Another box (the "cope") with guide pins that mate with guide holes in the lower box (the drag) would then be placed on top of the lower box.

    It is open on both ends and once in place on top of the lower box it will be filled with sand totally burying the wooden ball (pattern).

    (Rather than using dry, loose sand, the sand used for this process is dampened with oil so it sticks together when it is compressed. It is usually referred to as "green sand".

    Once the upper box is full of sand and the loose sand is tamped down so it is firmly around the pattern (called "ramming"), the upper box of sand is lifted straight up off of the lower box and then turned over.

    A hole that intersects the hollow pocket formed by the upper half of the wooden pattern is cut thru the sand to the outside to feed the molten metal thru.

    After removing the wooden ball (pattern) from the green sand in the lower box the upper box is then placed back on top of the lower box using the guide pins to align it and the metal is poured thru the hole to fill the cavity.
    The results is a solid, spherical ball.

    OK. Now, rather than having a simple wooden ball for a pattern we have a wooden ball with a fairly large wooden dowel sticking out of one side. The dowel is a precise length and when this pattern is being placed in the lower box the dowel is placed so it is laying in a horizontal position.

    The cope is placed on top of the drag and filled with green sand and rammed.
    When finished, the cope is removed, the pattern is removed and the feed hole is cut.
    (The hole is called a "gate" and the metal that is left on the casting after things cool is called a "sprue".

    While all of this is going on, another split box is being filled with sand.
    This box has a cavity cut into it much like a bullet mold and the cavity is a sphere with a round hole intersecting it.

    Once the green sand fills this mold and it is rammed, the box is opened and a sand sphere with a round sand rod sticking out one side is removed.

    (This is called a "core" and the pattern used to make it is called a "core box".)

    The size of this sphere is smaller than the size of the ball pattern used above to form the cavity in the cope and drag.
    For instance, if we wanted to end up with a 1/2" thick cast wall, this core sphere would be 1 inch smaller in diameter than the pattern used in the cope and drag.

    The length of the round sand rod sticking out of this sand pattern is exactly the same length as the cavity formed by the pattern that was used to form the cavity in the cope and drag.

    Now, the worker places this smaller sand pattern into the drag using the dowell cavity in the sand to position it and hold it in place.

    Once the cope is replaced on the drag with this inner pattern core in place the metal is poured.

    When it is cooled, the cope and drag are taken apart and the cast sphere is removed.
    Some pounding or hammering will break up the inner sand pattern and the sand can be poured out of the new, hollow ball.

    Once the sprue is removed and the hole thru the wall is machined for a plug you now have a nice new cannon ball waiting to be filled with powder and something to set it off.

    This sounds like a lot of time consuming work but in reality, once things are going, it can become a fairly rapid process.
    Remember, at a foundry where they are pouring thousands of pounds of metal there will be dozens if not hundreds of these copes, drags and cores being made to receive the molten metal.

    It's how tens of thousands of sand castings are made today.
     
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  7. Nov 12, 2017 #7

    F.G. Ford

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    Great read!
    Thank you for the information.
    Fred
     
  8. Nov 12, 2017 #8

    nkbj

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    And making shapes much more complex than a smooth hollow sphere. :thumbsup:
     
  9. Nov 13, 2017 #9

    Stumpkiller

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    My first full-time job was at an iron and bronze foundry.

    Zonie's description covers it well (wood patterns, green sand and core boxes) but there was another trick. A wax model could be used and then the green sand/box baked and the wax would run out - leaving a hollow. So all they needed was a tiny channel (smaller than sand could be vibrated out of).

    I used to hang around the pattern room just to watch them make the wood patterns. Talk about craftsmanship! This was in 1980 and these old duffers would construct things that would be a challenge with a modern 3-D printer and CAD system. And they used chisels and hand planes - in hard maple.

    That was Fairbanks Valve. They couldn't compete with imported valves. Pity. If you see an inverted triangle with an "F" in it it was one of theirs/ours. From steam locomotives to submarines and WWII naval ships.
     
  10. Nov 13, 2017 #10

    Zonie

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    While we're talking about castings, on some modern and almost all old engine blocks there are a number of sheet metal plugs pressed into the sides of the engine blocks.
    Most people call them "freeze plugs" saying they are there to protect the block if the water inside freezes.

    Actually, those are core plugs and they plug up the holes that were used to locate and support the core that forms the water jacket around the cylinders when the engine block casting was made.

    Ain't the Muzzleloading Forum great?

    A person can learn all sorts of things here without even trying. :grin: :rotf:
     
  11. May 4, 2019 #11

    Capn' D

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    You will find the discussions of sand casting iron balls around sand spheres held with chaplets in 17th and 18th century sources. The technique started with mortar bombs and hand grenades. Early cannon balls were all solid shot. Early 3lb grenades were all hardened clay. Later they worked out the iron hollows. Anyway, some areas and governments cast around centrally supported sand spheres, their balls flew straight. Other munitions were cast with the hollows off center and the balls tended to fly oddly. It gave some gunners a great advantage over others, especially at sea where moving targets and moving firing platforms made accuracy tough anyway.
     
  12. May 5, 2019 #12

    Treestalker

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    Find a copy of 'Round Shot and Rammers' by Harold Peterson. IIRC it had detailed drawings of the process Zonie was describing, along with beautiful drawings of all types of artillery pieces and carriages. It is a neat resource for cannoneers, and I really enjoyed my copy years ago, until it grew legs and ran off.
     
  13. May 8, 2019 #13

    nkbj

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    Absolutely nothing else has that twang odor of a foundry.

    By the way, speaking of hollow fused shot, wasn't the first five minutes of Sahara just one of the best shows you ever saw!
     

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