Hammerhead Stoneworks

Here is the step-by-step process I followed to cut the lintel for the pig roaster.

Here’s the stone I’ve selected and an assortment of the tools needed. The blue lines on the stone represent the cuts I’ll be making, one way or another. I decide to cut the right end off first, using feathers and wedges.

Before I use the hammer drill, I make small starter holes with the star-bit chisel. This prevents the drill bit from chattering on the stone, missing the mark and leaving unsightly scars. Before hammer drills, star bits were a traditional way to cut stone- swing the hammer, spin the chisel, swing the hammer, spin the chisel and on and on.

When cutting granite, I usually put feathers and wedges on three sides. To help guide the cut through the edges of the stone, I use my hand tracer, a recent purchase from Trow and Holden, to score a line where I want the cut to go.

Sweet!
An argument could be made for making this cut with the hand tracer alone; granite is hard and heavy, but it behaves very well under tools. I decided to use the feathers to save time. You should trace all four sides and that’s no small feat with a stone this large, at least working by yourself.

I followed the same process to make the longer cut along the width of the stone. Note how much straighter the ends are, where I traced the edges before splitting. It might have been a good idea to trace the whole line, though the rough line is in keeping with the overall aesthetic. I placed one wedge at the bottom of each side to guide the line.

The pencil line indicates the last cut to be made, to trim the top of the lintel. This is the face of the stone, freshly split showing a lovely line of quartz that will center over the opening of the roaster. Because of the clean line I want and the proximity to the edge of the stone I elect to use the hand tracer rather than the drill and wedges.

Here’s the risk of this operation- I am cutting very close to the edge of the stone, particularly as it tapers towards the bottom. It is very likely that the cut I’m making will choose the path of least resistance out of the stone, which would be to the back, rather than the bottom. The top of the stone will spall, leaving me with stone to remove by other means.

The hand tracer is surprisingly effective; it cuts a very, very clean line.

Unfortunately the top of stone spalls, leaving excess material on the top where my cut was trying to remove the thinnest flake of stone. The blue line indicates what remains to be removed. The grinder is my weapon of choice.

I score the top of the stone with my seven inch grinder using a diamond blade. I put the score lines about an inch apart. I then use my chisels to remove the excess material. Notice the dimple on the face closest to the camera; a matching dimple on the opposite side made it possible to lift the stone.

All that’s left is cleaning up the drill holes a bit.

There’s a new portfolio page featuring images from the Melrose Residence.

Up to this point, every time I’ve cut a stone using feathers and wedges, I have done so in a straight line. I decided to trying cutting a S shape out of this particular slab of sandstone paving because it was just too large for the walkway under construction; it would unbalance the whole composition. I wanted a sinuous line to accent the rolling shape of the path and to avoid creating a uniform, tiled feeling with long straight lines and square stones.

I drew the line over a few times, trying to get the right shape. I wanted a subtle curve, figuring it would be easier to accomplish. The X’s indicate where the drill holes be, evenly spaced. This is the back of the stone, so my scribbles and drill marks will be unseen.

I drilled six holes. Why six? Because that’s how many complete sets of feathers and wedges I had at the time. More would have been better. The holes are fairly shallow, about two inches. The stone itself is only three inches thick. I was careful to not punch the drill bit through the stone, as it would have created ugly knockouts.

I placed the wedges so that they turned along the line. This ensures that the force applied pushed the stone apart along the desired line. They look like soldiers marching.

Ah, so close. The actual split wandered from the desired line at the very bottom of the stone. Looking at it now, it’s clear that the split followed the path of least resistance. Another wedge even closer to the edge might have helped this, as would have reorienting the line so that the desired line followed the path of least resistance. Tracing the desired line with a chisel might also have been helpful.
There’s a lot of surface flaking where the feathers are set. I believe the wedges are a fraction to big for the drill holes so that they bind at the top and cause the stone to pop like this. This was a secondhand set of wedges that I have since replaced. Another reason to do this on the bottom of the stone.

Here are the cut stones in the pathway. The two big, rust-colored stones to the left side of the image are the cut stones flipped and set. Note the ‘dog paw’ pebbling just above the gray stone, to honor Dixie, a regular visitor to my lunches during the project.