How to Cut Slate

If you buy something through a link in our posts, we may get a small share of the sale.

When creating a new project at home, you may choose to work with slate. Most slate stock pieces will not be the exact size that you need so it is necessary to cut it up. Let’s take a look at some simple steps you can use to cut slate for your needs.

We outline several methods below for cutting slate:

  • chisel and hammer
  • slate cutter
  • angle grinder or circular saw

Before making any cuts, though, you have mark the slate for the cuts.

Marking the Slate and Cutting

No matter which method you use below,  you will need to mark the slate. This helps you know exactly where you plan to cut through the piece and can avoid confusion later. Once the lines are in place, you will be able to pick the right cutting method out of our other options.

Roof slate
  • To start, flip the slate so that you’re marking the bottom. It is often easier to draw and then cut a straight line across the bottom of your slate. If you want to cut it manually using a chisel or a hammer, flip the piece over along the underside of the tile.
  • To help minimize how much dust is produced when you cut into the slate, make sure to soak the slate in some water for a few minutes ahead of time.
  • Once soaked, use a pencil and a straightedge to help make the line. This is often the easiest way to get it done. The line is going to be the guide that you will use to make sure you are safe as you go through all of this.

Always remember the safety rules when you work through this process including:

  1. Choose a well-ventilated area: It is possible for dust and other particles to fly into the air. These are not good to inhale and may get into your eyes. Open the windows or work outside to keep the area ventilated.
  2. Wear the right attire: These will help keep you safe when you do the work. Things like construction gloves, long pants, a facemask, and goggles are good to use.

Use a Chisel and Hammer for Thin Pieces

One method that you can use is the chisel and hammer. This works well if you have thin slate to work through. This provides the most accuracy, but can be hard when you use a thicker piece of slate.

Some things to consider when choosing to use the chisel and hammer on thinner pieces of slate include:

  • Pick the right chisel: You should pick one that is really sharp and cold for the best results.
  • Never force the cut: You may need to do a few passes to get through even thin pieces of slate. Do not try to force it.

Here are the steps for cutting slate with a chisel and hammer:

  1. With your measured and marked line in place, you can score the slate with the chisel. Just place the chisel along the side of the straight edge and then draw the chisel a bit to score it. The straightedge is going to guide the chisel to get the line that you need. Add in just enough pressure to get a clear line, but do not push down too hard or risk cracking the slate. There should be a slight indentation for it, but not all the way through.
  2. You can then place the chisel on the line. Tap it with the hammer to break off sheets of the slate. Work down the line on that slate until you get the whole piece cut. If you do this well, you should have a clean slate piece.

Using a chisel and hammer can sometimes result in some fragments on your slate. You can chisel these away, or use high grade sand paper to wear them down and smooth them.

Using a Slate Cutter for Medium Thickness

Another option that you can choose to use when cutting through the slate is to use a slate cutter. Similar to a tile cutter, a slate cutter is a good option to use if the slate is medium thickness and can’t be cut through with a hammer without spending hours of energy on it.

A slate cutter is a tool that has carbide tipped blades that will not wear out very much when you cut through the slate. They sometimes resemble large scissors and can cut through the slate without a lot of hassle in the process.

Here is the process for cutting through slate with your slate cutter, once you’ve made your measurements:

  1. Line the straightedge: Choose how big the piece of slate should be and then line the straightedge up to it. This is going to guide you as you do the rest of the work.
  2. Score the line: Use some kind of sharp tool to help score the line. A chisel or a trowel will work well for this to make a small indent into the piece that you are using.
  3. Line up the slate cutters: Now that the scored line is prepared, place the blades of the cutters onto the line. One blade is on the top and the other is underneath. You may also want to clamp this onto the workbench to get it to stay put.
  4. Squeeze the handles and cut: Hold onto the slate cutter with both hands and then squeeze down to start cutting into the slate. You will need to use a bit of pressure. You will need to cut as straight as possible and all the excess slate will fall to the side.

This can be a little difficult to do and you may need to use more pressure than you are used to. But with a little practice, you will see that it will do the work that want without a lot of issues too.

Man holding a circular saw

Using Power Tools for Thick Pieces of Slate

If you are using a large piece of slate thicker than a 1/2″, you probably want to work with a power tool to make this process a little bit easier. Hand tools only get you so far, and thicker pieces of slate benefit from the power that a saw brings.

There are a number of different types of power tools that you are able to use, but the most common are circular saws and angle grinders. Both of these tools are highly convenient and easy to use.

You need to double check that they are diamond tipped or carbide tipped, otherwise the blade is going to dull out fast. Some of the things to remember when using these include:

With this in mind, the process for cutting is the same for each:

  1. Start by clamping the slate so it will stay put on the workbench. With the power tools, you do not want the slate to shift around or the line will get uneven. Clamp the slate so that the part you want to remove will hang over the workbench. If you do not have this part hang over, the power tool will slice right through the work table.
  2. Figure out where you would like to draw the line on the slate to have it be the size that you would like. Check the line a few times to make sure that it falls where you would like. Mark the measurements on all sides if you need it to be adjusted all over. Then use a straight edge to make a full line.
  3. You can either choose to just slice right on the line or you can go through and score the line a little bit. Scoring has the advantage, even with the power tool, because it makes it easier to see where the line is going to be and can keep you even as you do the work.
  4. Take the blade of the power tool and place the blade along the line before pulling the trigger. You need to also plug in the saw and make it turn on. Use both hands while placing the blade right above the line that you drew on the slate. Then pull the trigger and get the blade to spin.
  5. Slowly lower the power tool that you want to use so it meets the line. Then move it up and down, cutting through the slate slowly. Continue to hold onto the trigger and move the power tool across the line.
  6. You may need to make a few passes through to get the slate cut into the right piece. If this is done right, you should have a straight edge when done.

Again, should you need to, a chisel and high grit sandpaper can help smooth any rough edges.

Summary

There are different methods that you can use to help cut the slate that you want to use. It will depend on the thickness of the slate that you are using, including chisel and hammer when you have a thin piece or a power tool if you plan to cut through a thicker piece of slate. Taking your time to do the right measurements will make a bit difference in getting the slate to be the exact size that you need.

An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.