How to Drill a Hole in a Large Rock [Easy to Follow Guide]

It is summer already; the backyard landscape design needs a little retouch. How about adding a bubbling rock fountain attached to your koi pond? The fountain will be a new source of tranquility as well as a summer’s cool gift for your koi carps.

Grab your toolbox and let’s get to work. A large rock with a hole to flow water through is the first thing you need to build the fountain. Wait, a hole in a large rock?

It seems like a job for Arnold Schwarzenegger with a huge rock drilling machine! Actually, it’s not. Will you be surprised if I tell you that you can be Arnold Schwarzenegger yourself and easily drill any large rock! Want to know how to drill a hole in a large rock?

Check these easy steps to drill a hole in any large rock.

Step 1 – Rock Selection

The first step to drill and build a bubbling rock fountain is selecting a rock that will last longer and be friendly for pond life.

• Sandstone

You might think of sandstones as they have a variety of color ranges. Their eye-catching colors may attract you, but they are known for having a high-water absorption rate.

Sandstones have 10%–35% porosities, which are considered to be high. Due to high porosity, they are very vulnerable to damage. Your stone might break down into pieces while drilling.

So, if you want to drill a hole in a large rock without breaking, avoid sandstones. Also in some cases, bacteria, and other substances may leave permanent stains on the rock, which means it’s not really a good choice for your koi pond.

• Granite

Granite is timeless and one of the hardest stones on the planet. Unlike other stones, granite does not contain a porous surface. Pores in stone trap water, making the stone fountain chip over time, especially when water freezes.

This durable stone stays in good shape for a long time; this makes it a perfect fit for bubbling rocks and backyard fountains. To drill a hole in a large rock for a bubbler fountain, granite is just the stone we are looking for.

Step 2 – Collecting Gears and Safety Equipment

Our stone or boulder selection is complete, now we need some real man’s tools and safety equipment to get the ‘Arnold Schwarzenegger’s job’ done!

1. Heavy-duty Variable Speed Drill

A heavy-duty variable speed drill is the first tool we need for the job, though it would be way cooler and ‘Arnold Schwarzeneggery’ if we could do it with a demolition jackhammer! It’s better to know what we are working with.

A variable-speed drill machine is a type of drill that has an adjustable clutch for drilling various types of durable materials such as large rocks. The main science stuff lies at the different rotational speeds of the bit, which science geeks generally mention as torque.

It can use a large range of bits for various purposes such as drilling large rocks, metal, granite boulders, hardwood, and softwood depending on the durability of the material.

2. Coring Bit and Drill Bit Guide

A coring bit is used for cutting and removing a cylindrically shaped piece from a hard material. It has a hollow center that creates a hole in the rock.

And the guide drill bit guides the corer bit and helps it to stay stable while drilling a flat, spherical, and round surface.

3. Diamond Tip Drill Bit

After that, we need a diamond tip drill bit for our drill machine. Diamond tip drill bits are used for drilling holes through hard non-wood surfaces such as granite, stone, glass, and other strong or fragile materials. These sharp bits are perfect for drilling any large rock.

To achieve the best results from diamond drill bits, you need to operate them at a lower torque and lubricate with water to keep the bit cool. Diamond bits have a wide range of shapes and sizes but they all can be divided into two basic types, hollow tip, and solid tip.

Here is a guide to choose the right drill bits for rock.

4. A Vise

A vise is our next tool for the job. A vise is a tool that has two jaws, one is fixed and the other is movable. The jaw’s movement is generally done by a screw or a lever. This tool is used for holding the workpiece during the drilling operation. It also gives stability while drilling a boulder, especially the loose stones.

5. Safety Equipment

Last but not least we will need the safety equipment; safety goggles, a protective air mask, and protective hand gloves. While using a heavy-duty drill machine, even a small piece of debris could cause a serious injury, especially an eye injury. Always put on your safety gear while drilling.

Step 3 – How to Drill a Hole in a Large Rock (the key steps)

Okay, we have our boulder and tools ready. Now it’s time to practically answer the question of the day, ‘how to drill holes in large rocks for a bubbler fountain’.

1. Planning and Drawing

There is a very famous saying ‘failing to plan is planning to fail’. Woah, these words sound heavier than those granite boulders. Anyway, planning where to drill and how large or deep the hole should be is the first task for drilling a large rock.

Put pencil markings on the areas where you want to drill. Use heavier strokes so that it becomes easier for you to spot them while drilling.

2. Choosing the Right Drill

Before you start drilling that big granite rock, you need to make some final checking. If the boulder that you are working with is large in size, a cordless hammer drill will be great for the job.

But if you are comfortable with a corded hammer drill, you may go with it as corded hammer drills allow you to use them at a position that you find yourself comfortable while drilling. Also, select the size of the drill bit that fits the task.

3. Measurements and Adjustments

Measure the width of the boulder to determine the length of the drill bit. The bit has to be long enough to drill through the boulder.

• You can put some modeling clay under the stone to protect your work table from getting damaged by the drill machine.
• Place your selected boulder in between the leather. After that, place it in the vice to keep it steady. This will give you a smooth drilling experience.
• Now it’s time to gear up your heavy-duty variable speed drill. Make sure you have the batteries charged freshly. At least charge it to a limit that you think will be sufficient for drilling a hole into a large hard boulder.
• Followed by that, start loosening the chuck of the drill. You may use your hands, a wrench, or a Phillip’s head screwdriver to do the job. Now, insert a diamond-tipped drill bit into your heavy-duty drill machine.
• After insertion, tighten the chuck of the drill properly. Now, you are ready to drill some hard boulders.

Put on your safety gloves, safety goggles, and protective air mask to avoid serious injuries.

4. Drilling a Hole in the Rock

Place the drill bit over your pencil marked point on the rock.

• Operate the drill at a slow speed first, and keep the bit vertically to the surface of the rock. This will give you a smooth and perfect-looking hole opening as soon as you begin.
• Now slowly apply downward pressure to the rock while keeping the drill vertical to the surface. Slowly gain speed and keep increasing the downward pressure. But be careful of high speeds, as this might cause the drill bit to burn out.
• Use a lot of water for lubrication and to keep the diamond drill bits protected from burning out.  Keep the drill steady and straight, maintain the downward pressure until you see the tip of the drill bit from the other side of the rock or you reach your desired depth.

After finishing, take out the drill bit slowly from the hole and do not touch the bit with bare hands as it might feel very hot due to friction.

How to Make a Hole in a Rock without a Drill?

No, we haven’t arrived in a caveman’s cave using a time machine! You may stop wandering around!

Think of a scenario, ‘your drill is broken and you need to make a hole in the rock before your koi carps start protesting for the bubbling rock you promised’! This might sound like a pretty bad joke but you can actually make your own bow drill!

Follow this fun method to build a DIY bow drill. It may take years for rock.

• First, select two sticks, one flexible enough to be bent like a bow, and the other with a pointy edge on one side. Next, tie a string on both ends of the flexible stick with proper tension and it will get a shape exactly like a bow.
• Now, mark on the surface where you want to drill and place the stick with the pointy end. Wrap the string of your bow around that stick.
• Finally, you can drill into the surface by applying downward pressure and moving the bow back and forth simultaneously.

Note that this method works effectively on wood. But it might work on thin stones as well.

Why not spend a Sunday afternoon trying out this cool caveman technique to find out which stones you can actually drill with your handmade bow drill?

Conclusion

Follow these steps to easily drill into a stone. But there is no guarantee that you will not end up getting a broken stone.

Some stones may have internal materials which contain fracture lines naturally, but in a normal case the stone may get fractured due to excessive pressure, or when you are unable to operate the drill properly.

If you don’t want to risk the stone you may call an expert. But we suggest you give it a try. Hoping your koi carps get the best bubbler fountain.