1. Mick West

    Mick West Administrator Staff Member

    Metabunk 2019-01-11 09-59-24.

    NBC News say these steel bollards were "sawed through", but there appears to be oxy-cutting slag on the cuts, especially on the far left (above)

    Metabunk 2019-01-11 10-01-08.

    The cuts appear too ragged in many parts to be from any type of saw - although the bottom section on the right does appear fairly clean - it still has some slag on it.

    NBC News says:
    The photo above seems to just be a concrete filled bollard, with maybe 3/8" steel, and it has been cut. But it seems misleading to say it was simply sawed through. It seems more likely it was done with a combination of tools. Perhaps oxy cutting was used to create the initial hole, allowing the concrete to be chipped away, and a saw inserted.

    Oxy cutting sounds like it would need heavy equipment, but you can actually make a fairly cheap and light DIY version of a thermic lance, like this one by @NightHawkInLight

    Source: https://www.youtube.com/watch?v=EA-VCaBUsCA

    My own experience of cutting steel with "industrial tools" is from using an angle grinder with a cutting disk, and from using a reciprocating saw with a tungsten carbide blade. Both of these were on cheap battery-powered mobile tools.
    Last edited: Jan 11, 2019
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  2. Mick West

    Mick West Administrator Staff Member

    I did some speed tests, and you can cut through 1/4" A36 steel at a rate of about 1" per minute with a hacksaw and 4" per minute (15 seconds per inch) with a tungsten carbide reciprocating saw.

    Metabunk 2019-01-11 10-56-22.

    Metabunk 2019-01-11 10-56-54.

    Sadly I could not find my cutting disk, but I suspect it would be similar to the reciprocating saw, and it has the advantage of being able to make cuts in any position.
    Last edited: Jan 11, 2019
  3. Mick West

    Mick West Administrator Staff Member

    The retracted Gov report lists eight techniques BT-1 to BT-8, mostly with names retracted. Generally they used a single primary tool and a secondary tool. The two techniques that were listed unredacted were:

    BT-6 - Plasma Cutter
    BT-8 - "Quick Saw"

    A portable plasma cutter would make short work of the exterior steel, although it's not really backpack-portable in the way some other techniques are.
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  4. DavidB66

    DavidB66 Member

    I don't know what tools were actually used, and as Mick says the cuts look rather ragged, but for what it's worth I don't see any problem in cutting through the 'bollards' quickly using cheap and easily available tools. I can't find any statement of the thickness of the bollards, but from the video it seems to be inches rather than feet. A few years ago I had some fence posts in my garden removed, the posts being about 5 inches across, and made of concrete with some kind of rebar core. I was expecting the workmen (from an ordinary local garden services business) to find it a tough job, so I was mildly surprised to see them bring out a small angle grinder, plug it into my domestic power supply, and cut through each post in a minute or two. (I was also expecting them to dig out the 'roots', but that is another story.) I mentioned how surprised I was at the speed, and the guy just said 'oh, these diamond blades will go through anything'. On further research (i.e. looking up 'diamond blades' on the internet) I realised that they are cheap and commonplace tools. Even in Mexico, I would guess.