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When my son Robert called in a mini excavator to scrape the site here for an addition on his house
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we thought we were just going to run into a few inches of soil and then limestone bedrock, but we
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found that there were some thick slabs, you know, over 12 inches, maybe 16, 18 inches thick, that
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were loose, not attached to the bedrock, and we needed to get them out of the way. But we ran into
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a big stone that the excavator could not move, so we employed an ancient technique involving some
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simple tools called plug and feather wedges to split that rock apart so the machine could handle
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it. So take a look and see how we did it. Our objective is to try and break this rock in half
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That will make small enough pieces that the excavator can move it, and here my son Robert is
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drilling one inch diameter holes in the rock to accept what are called plug and feather wedges
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You'll see those closer up a little bit later. He's using a DeWalt corded rotary hammer with a
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one inch carbide bit. This is the hardest hitting hammer that DeWalt offers, and it is also the
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fastest rotary hammer I've ever used. I bought my first one back in the 80s, and this is far
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superior and faster than that machine certainly, and also any others that I've used so far
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Now when he's drilling you'll see him withdraw the bit from time to time, and that's just to help
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clear out the dust that's building up to reduce the friction on the machine, and it does end up
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speeding up the drilling process. He's drilling holes about every six to eight inches along a
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straight line, and here the excavator is keeping busy clearing out some soil. He's actually scraping
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it off bedrock. The slab of stone we're splitting in half probably was originally attached to the
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bedrock, but it's not now, so as big as it is, it's still not suitable for a house foundation
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The whole drilling process probably took less than 15 minutes, which really says a lot because
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we're drilling some big holes. They're deep, almost full length of the bit. Here the plug
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and feather wedge is going in. There's essentially two feathers with the curved tops that go on each
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side of the hole, and then the plug, which is actually a wedge, goes in between them. So when
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all of those are installed, it comes time to use the hammer to actually split the stone. It doesn't
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take a lot of force or power, just one or two good hits on each one in a repetitive way is developing
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tremendous pressure along the same line, and that's what splits this thing apart
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Nothing really dramatic happens when you're using these things. It's just a slow developing of the
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crack on the line where all the holes are drilled, and you can see that crack starting to develop
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here now. This kind of limestone has some different layers in it. It's not exactly flaky, but
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it probably won't break in a very clean line just because of the nature of the stone. But yeah
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you can definitely see the cracks opening up, and this is what we want to see
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The wedges are about as far down now as they're going to go, so as much pressure
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that can be applied is applied, and now it's time to actually see if this thing's going to break
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So, yeah, it's no problem. As you can see, the parts hadn't moved apart very much, but clearly we've
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broken this in half. We could have made it smaller too, but this is as small as it needs to be
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for that excavator to do its job and to pull that stone away. We're taking the wedges out here now. You can see how they went right down into the holes
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The break isn't all that clean. This isn't optimal building stone, but it could be used
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for construction, and it's really easy to lose one of those plug or feather wedge components
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so we're careful to search around for those. But this is the second half of the stone being lifted
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and moved out of the way
