Using Feathers and Wedges to Split Stone

Splitting Stone(3)

Feathers and wedges (also called plugs and feathers or wedges and shims) are handy tools for splitting large stone blocks into small, nicely shaped pieces. Feathers and wedges were historically used extensively for quarrying rock out of hillsides. Even today, feathers and wedges still provide a reliable and surprisingly fast method of splitting rock into reasonably sized and shaped slabs.

How They Work

Feathers and wedges work quite simply. An examination of any feathers and wedge set reveals that the wedge, which has but a relatively slight taper, when pushed down causes the feathers to expand outwards. The feathers are carefully shaped, allowing them to fit into a ROUND hole and to expand outwards evenly from top to bottom as the wedge is pushed in.

Feathers and Wedges
Three sets of feathers and wedges. These are a modern set; old-time sets look slightly different but work exactly the same. The long wedge in the middle when pushed down forces the metal “feathers” apart. There are many sizes of feathers and wedges; those shown are 3/4″, which is somewhat small as far as feathers and wedges go.

Since stone is relatively weak in tension, a set of feathers and wedges placed in a row of holes in a rock and carefully hammered down will create a strong tensile force that will split the stone along the line of feathers and wedges.

Using Feathers and Wedges

To begin with, you will need to determine what size your feathers and wedges are. They come in many sizes, ranging from small to massive. For general use, 3/4 inch seems to be a good choice. To use the feathers and wedges, you will need a masonry drill and a drill bit that is the same size as the feathers and wedges; so, of course, if you have a 3/4-inch set of feathers and wedges, you will need a 3/4-inch masonry drill bit.

Determine where the stone is to be split, then chalk on the stone a straight line along the desired splitting line of cut. Now, starting, say, 6 to 8 inches from the edge of the stone, drill a 3/4″ hole along the splitting line. Drill as far down as is required for the wedge of the feathers and wedge set to have enough room to be driven completely down. Drill another hole 6 to 8 inches away from the first along the splitting line and so on until the stone has a regular row of holes along the line of splitting. For very hard rock, it may be desirable to drill the holes more frequently; alternatively, when using soft rock or large feathers and wedge sets you may be able to get by with drilling the holes farther apart.

Splitting Stone
The holes for the feathers and wedges are drilled with regular spacing along the desired line of cut. The holes are started in this picture for clarity. A modern hammer drill is perfect for drilling holes in the stone; back in the day the drilling was done with a special type of chisel and a very dedicated worker.

Once the holes are drilled, you are ready to split. Place the feathers and wedges in all the holes. They should be placed such that, when the wedge is pushed down, the feathers will push out along the desired line of cut. In other words, the feathers should be placed parallel to the desired line of cut.

Splitting Stone (2)
The feathers and wedges shown in place. They should expand such that a tension is formed along the desired line of the split. Once the sets are tight in their holes, the wedges should be hammered down one after another evenly, striking each wedge but once before continuing down the line. Once the end of the line is reached, repeat the procedure.

To split the stone, tap all the wedges down gently with a small sledgehammer until all the wedges are tight. Then, starting at one end of the line of feathers and wedges, tap (don’t strike hard) down each wedge once, working down the line in a sequence, starting over once the end of the line is reached. Keep tapping down the wedges, increasing the force as needed, until the stone splits.

Splitting Stone(3)
Once sufficient pressure is applied by the feathers and wedges, the stone will split. How regular the split is will depend primarily on how evenly and properly oriented the feathers and wedges are placed. Hidden anomalies in the rock can cause some deviations along the line of splitting as well.

If considerable force is needed to be applied before the rock will split, you will need to decrease the spacing of the feathers and wedges or use a larger set.

Historical Uses of Feathers and Wedges

Feathers and wedges are tried-and-true. Historically, many stone structures were erected using stone split with feathers and wedges. As an example of how the quarrying was done historically, here is a quote from Walter Sharp, famous for building many of the stone bridges in Cowley County, Kansas:

“….All over Cowley County, especially the eastern part, splendid ledges of rock crop out; these ledges range in thickness from 12 inches up to 36 inches. After the dirt is stripped off, these great slabs of rock lay there and are split with plug and feather into blocks that somewhat resemble a paving brick; the size would perhaps be 18 inches in thickness, 24 to 30 inches wide and from 4 to 8 feet long. These rock will be picked up by derricks from their bed, swung around [to] a convenient place to work on, putting the smoothest split side up….”

Walter Sharp, “Tyranny in Kansas Road Building,” The Wichita Eagle, September 8, 1922.

Unless the stone was further smoothed and trimmed after being split, the feathers and wedges will have left a distinct half-round hole on the faces of the stone — mute evidence of how the stone was quarried.