When it comes to construction, particularly for an amateur, drilling into a stone wall is one of the more daunting tasks you may face. It pays to use extreme care in completing the task, and use the proper tools and safety precautions.
Step 1 - Determine the Hardness of the Stone
Natural stone is often a very hard material. There are stone walls made of softer kinds of stone, however, and these require a different type of bit. The most important factor in successfully drilling a stone wall is getting the right drill bit. The second most important factor is the drill itself.
When choosing a drill bit for your stone wall, remember that the harder material needs a somewhat softer bond on the drill bit, allowing a little more movement and freer drilling. This will allow you to drill faster.
For extremely hard stones, use a metal bonded diamond drill. These have a longer life and last through more drills per bit. For soft stone, an electroplated or nickel bonded drill bit will provide a better solution with a longer life. It may be more cost effective as well.
A diamond core bit is used for larger holes, while a diamond solid or diamond drill bit is used for smaller holes, from .001 to 3/8 inch in diameter. If you are drilling a stone wall for construction, it’s likely that you will need a larger hole, so a diamond core bit will work for you. Consider what you are attaching to the wall and what fasteners you plan to use for the purpose.
If you are drilling a longer hole (over 3 or 4 inches) you will want to use an SDS and drill bit or core cutter. They will cut deeper holes with ease.
For shallower holes, a standard hammer drill will work.
Step 2 - Measure and Mark
Mark the drill holes carefully on the wall. Measure twice, and mark with chalk in a contrasting color from the wall.
It is difficult to repair a mistake in drilling on a stone wall, so make certain you have the holes in the right place before you begin.
Step 3 - Drill Holes
Use a hammer drill with the appropriate drill bit. Use water or a lubricant to cool the bit as you drill. Rest from time to time, remove the drill, and spray the bit with coolant or water. Spray into the hole as you drill as well. It helps to have a second person for this task.
If you can’t use a lubricant or water, be sure to buy a laser welded diamond core bit that is made for dry stone drilling.
The drilling process can be slow, so take care. If you run into a spot that is difficult to drill, don’t apply too much pressure, which can break the bit. Apply a gentle and steady pressure instead.
Start the drill without the hammer feature, then add the hammer feature later to avoid splitting the stone.
Step 4 - Clean the Holes
Flush holes with water or lubricant after drilling is completed.