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Thread: How a backyard pendulum saw sliced into a Bronze Age mystery

  1. #1
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    Default How a backyard pendulum saw sliced into a Bronze Age mystery

    Excerpt
    Nicholas Blackwell and his father went to a hardware store about three years ago seeking parts for a mystery device from the past. They carefully selected wood and other materials to assemble a stonecutting pendulum that, if Blackwell is right, resembles contraptions once used to build majestic Bronze Age palaces.

    With no ancient drawings or blueprints of the tool for guidance, the two men relied on their combined knowledge of archaeology and construction.

    Blackwell, an archaeologist at Indiana University Bloomington, had the necessary Bronze Age background. His father, George, brought construction cred to the project. Blackwell grew up watching George, a plumber who owned his own business, fix and build stuff around the house. By high school, the younger Blackwell worked summers helping his dad install heating systems and plumbing at construction sites. The menial tasks Nicholas took on, such as measuring and cutting pipes, were not his idea of fun.

    But that earlier work paid off as the two put together their version of a Bronze Age pendulum saw — a stonecutting tool from around 3,300 years ago that has long intrigued researchers. Power drills, ratchets and other tools that George regularly used around the house made the project, built in George’s Virginia backyard, possible.

    “My father enjoyed working on the pendulum saw, although he and my mother were a bit concerned about what the neighbors would think when they saw this big wooden thing in their backyard,” Blackwell says. Anyone walking by the fenceless yard had a prime view of a 2.5-meter-tall, blade-swinging apparatus reminiscent of Edgar Allan Poe’s literary torture device.
    How a backyard pendulum saw sliced into a Bronze Age mystery (ARTICLE LINK)

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Cool!
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    And thousands of years later the material is still binding, the blade is getting stuck and the craftsman is cursing—only the swear words have changed.
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    They must have had a good alloy of bronze, you'd think the stone would be sufficiently harder to just wear away the blade.
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    The emery sand probably did a lot of the work

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    They would have needed carborundum grit. I wonder if it was available to them?
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    It appears that the emery sand mentioned in the OP article is mostly Aluminium oxide which can have a hardness of 9. Carborundum (Silicon Carbide) also has a hardness of about 9.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Is emery sand easily obtained ? Carborundum is in the form of non gem grade sapphires, I mined sapphires as a young man in Australia, the low grade material was plentiful.
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  9. #9
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    A quote from the link in the OP.

    Those workers probably used highly abrasive emery sand from the Greek island of Naxos to amplify the grinding power of their swinging saws, Wright adds.

  10. #10
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    I have done some hiking in an area near the Georgia-North Carolina border where Carborundum was once mined. I have read that it is still possible to find gem sapphires in the area.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Quote Originally Posted by Jimmy W View Post
    A quote from the link in the OP.
    I missed that, thanks.http://www.ekathimerini.com/220888/a...ining-on-naxos
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Do you think it would be possible to add the emery sand into the molten bronze so it would be embedded into the blades? The melting point of Aluminum oxide is over twice that of bronze.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Quote Originally Posted by PeterSibley View Post
    They must have had a good alloy of bronze, you'd think the stone would be sufficiently harder to just wear away the blade.
    Copper will work
    Glass engraving encompasses a variety of techniques. One notable form is intaglio work, with images and inscriptions cut into the surface of the glass through abrasion. Glass engraving tools are therefore small abrasive wheels and drills, with small lathes often used. Engraving wheels are traditionally made of copper, with a linseed oil and fine emery powder mixture used as an abrasive.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    It would float as a scum on top of the melt, their densities are too different. A slurry in the cut is more likely .... unless they could find a way of manually pressing the emery into the cast bronze. Much the way a gem cutter's copper lap disc has diamond dust embedded in it to cut sapphire, aluminium oxide IIRC.
    Last edited by PeterSibley; 05-13-2018 at 04:22 AM. Reason: typo
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Why is it that humans can develop such ingenious techniques and be so stupid at the same time?
    The definition of stupid has got to be the belief that more guns will negate the bloodshed done with guns.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Quote Originally Posted by CK 17 View Post
    And thousands of years later the material is still binding, the blade is getting stuck and the craftsman is cursing—only the swear words have changed.
    I bet the meaning of them hasn't changed a bit!

    Cool story - once again my thanks to SharpieFan for these great posts. A particularly apt handle for this story, I might add...
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Men have the Y chromosome. It's for tools. And guns. And throwing things. And heavy drinking.

    But that's all it's for.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Quote Originally Posted by PeterSibley View Post
    It would float as a scum on top of the melt, their densities are too different. A slurry in the cut is more likely .... unless they could find a way of manually pressing the emery into the cast bronze. Much the way a gem cutter's copper lap disc has diamond dust embedded in it to cut sapphire, aluminium oxide IIRC.
    I understand the problem you describe,but I would think fusing the grit to the metal would make sharpening the saw very difficult.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Quote Originally Posted by PeterSibley View Post
    They must have had a good alloy of bronze, you'd think the stone would be sufficiently harder to just wear away the blade.
    Is it not quite hard to cast a sheet of bronze of uniform thinness?

    Copper can be hammered flat and thin, so perhaps they used copper blades?
    It really is quite difficult to build an ugly wooden boat.

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  20. #20
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Lost wax would work well, it was the usual casting method I think.
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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Bronze can also be hammered.

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    Default Re: How a backyard pendulum saw sliced into a Bronze Age mystery

    Quote Originally Posted by Jimmy W View Post
    Bronze can also be hammered.
    Not as easily as copper, annealing a sheet would be a pig, which is why bronze age axes and swords are all cast.
    It really is quite difficult to build an ugly wooden boat.

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