As far as rocky materials go, slate isn't very hard, and a 4-inch angle grinder can generally cut through a 1-inch or thinner slab in a single pass without the need to keep the blade wet. When cutting slate, it is critical to wear a dust mask. The fibers in the material will fly off when cut, and they are extremely fine and able to get into your lungs.
Slate is sold in sheets that are either 6 or 8 feet long and 3/4 inch thick. The best tool for cutting these sheets is a slate knife, which can be bought from any woodworking store. It has a sharp steel edge that slides easily under the slate and allows you to saw away large chunks quickly and accurately. You can also use a backhoe or a stump grinder to grind away the slate surface by placing an angle grinder on its side so that it can sit flat on the ground. This is useful if you want to create a clean line of demarcation between your landscape area and your house foundation.
You should wear protective clothing and eye protection when using an angle grinder. The slag produced when grinding slate cannot be disposed of in an ordinary trash bin; instead, it must be taken to a hazardous waste disposal site.
Because slate is stone, which is significantly harder and denser than wood or plastic, it lacks the soft cutting area seen on a standard cutting board. It is possible to use a slate board as a cutting board, but you run the danger of dulling your knife or, worse, chipping or damaging your slate. If you want to use your slate as a cutting board, we recommend using a non-stick surface protector.
Slate may be cut with a variety of instruments. A wet tile saw, a conventional circular saw with a tile blade, an oscillating multi-tool, or even a tile nipper will all do the job. However, we like to use our Dremel with a diamond tile cutting wheel attached. It's easy to use and effective.
First, using a pencil, draw several reference points on your slab that are at least 1/4" apart. These will help you later when trying to get your slab back into its original position after cutting it. If you don't want to mark your slab, then you can also use a compass to make these marks instead.
Next, find a flat surface where you can safely mount your slab. You can use a table top if you have one that is suitable for using a grinder on. Otherwise, you can use a piece of plywood or concrete. Make sure that you are working on a clean surface with no dust or other materials that might get ground up and spread throughout your house.
Now, using the diamond tool attached to your Dremel, grind away at the slab until it is completely hollowed out. Take your time with this process so you don't heat up the slab too much. When you are done, you should have a nice hollow shell that looks similar to the picture below.
If you don't have an angle grinder or a circular saw, you can cut the slate using a hammer and a cold chisel. To begin, lay your straight edge on the line you've drawn and score the slate with your chisel. You can use the edge of the tool to guide where you want to strike it, but be careful not to hit any other stones in the pile.
Next, bring the chisel back over the top of the stone to create a flat surface. Continue doing this until you've removed all the slates. Now that they can be used as roofing material, many people will simply take them out of the yard and use them elsewhere.
Slate is a common building material in Northern England and Wales. It's hard to work with because it's so brittle, but if you find some old pieces then they're worth bringing home!
Slate is my favorite material to work with since it performs precisely as expected and gives you total control over the stone. You must be careful not to overgrip the chisel and to maintain a relaxed hold, enabling the chisel to become practically an extension of your hand.
Once you have cleaned the slate of all impurities, there are two main methods for carving it. The first is called dry carving and the second is known as wet carving.
Dry carving is done with a sharp tool on a flat surface. The carver removes all the outer layers of the slate until only the inner layer remains. Then it starts all over again with a new piece of slate. This method produces a fine quality product but it can be time-consuming. It also requires that you wear protective clothing including leather gloves to protect yourself from the sharp edges of the slate.
Wet carving uses a mallet or another heavy object to hit the end of the chisel against the surface of the slate. This breaks off small pieces of slate that can then be used to fill in any gaps in your design. Wet carving is faster than dry carving and can produce a more rustic look, which may be appropriate for some projects. There are tools available that can help you with both types of carving; ask your local woodworker what kind they recommend.
The slate does not appear to cut very well, but it does appear to burnish or polish edges quite nicely. It's not so excellent for polishing plane-iron flat faces; it just takes too long to produce a nice finish, but the ruler approach would probably work. I found one advantage in sharpening my slates; it makes cutting straight lines much easier!
I've seen some people say you can't sharpen slate and that you should throw them out after one use. But I think this is wrong! Slates can be sharpened like pencils and used many times over. The only real problem with slate is trying to find someone who will sell you a really good one now and then.
So, yes, you can sharpen a slate. Just take out the stone once a month when sharpening your pencils to keep them working smoothly.