Feathers and Wedges: Ancient Stone Splitting

The dump truck backed up and it tilted. And out poured a huge pile of boulders that were way too big for me to lift, let alone move. These were supposed to be "2 man rocks." They were a bit bigger than that.

The back yard was ruined in a minute.

After a full refund it didn't seem like they were going to be removed. So it seemed like the best thing to do would be to cut them all in pieces.

Feathers

Wedges

A slice of rubber hose to bind them together

A small sledge hammer

A hammer drill and 1/2" bit

Buying tools is no fun, especially when they seem so simple to make. I realized I could forge them out quickly from scrippiescraps I have in the bucket.

My friends at the local spring company had given me lots of side cuts from leaf springs. These were roughly semicircle in cross section. They were also free. Aim for free, guys. Done Dirt Cheap.

Here's how I did it:

1. I cut two feathers to length. Mine are about 2.5 inches. These feathers end up a shape I can't really describe, though they are very simple. They are semi-cylinders with a 1/2" shoulder and a tapered waist. You'll have to watch the video above to make sense of the shape. The main feature is that the feathers must have flat bellies that, when held together, must make a circle at their bottom tips.

2. I forged a long wedge. This is a super easy shape, perfect for a 1/2" square bar, 4 inches long. The wedge should taper from a full 1/2" at the top down to about 1/8" at the point. I made a light octagonal chamfer around the thick end. It just looked right.

3. Sand the matching faces of the three pieces until they slide smoothly. When assembled the wedge should glide between the feathers. When the wedge is slid all the way down to the tips of the feathers it should move them apart that 1/8 inch and make the waist an exact circle the same size as the hole their in. That will be enough to crack very large stones wide open.

4. Heat treat the little feathers by bringing their tips to dark straw color. The feathers must be harder than the wedge so they don't deform or break inside the hole drilled in the rock.

5. Drill the hole in the rock.

Drill 1/2 inch holes in the rock you want to turn into two rocks at a depth of about 3.5 inches. Line the holes up on the along the line you want the stone to split at.

Insert the feathers and wedges into each hole as one unit with the wedge point all the way at the top of the feathers. The feathers should be just out of the hole up to their waist. (I can't think of a better word for it than "waist".)

When inserting the feathers and wedges, remember to orient them so that the feathers will put outward pressure perpendicular to the line you want the stone to crack along.

The sounds that come from tapping these wedges down between their feathers is delightful. They have so much character that I find myself really listening to the tones and switching up which wedge to hit and how hard to hit it. Something about reading the rock and the sound together is very satisfying.

And the best sound of all is that wet apple-crack sound.

Most of these boulders are hard, Lake Superior basalt. Basalt is no joke- on the Mohs hardness scale it's somewhere between quartz and titanium carbide- but when it cracks, it cracks with a sound you have to hear in person to really enjoy fully. It's a beautiful thing.

Once a crack forms all the pressure will come off the row of feathers and the wedges will lift easily out. I advise having a very strong magnet to retrieve the fallen feathers out of the muddy holes.

Lastly, force the crack open all the way with an iron Johnson bar (which you just need to own a Johnson bar if there are any large rocks in your world).

That's it. Please write me if you make any part of this project. I'd love to see any improvements you might make. And please subscribe to my YouTube channel for more content. Thank you for reading.

DDC