How to Drill Large (and Deep) Holes in Wood

How to Drill Large (and Deep) Holes in Wood

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Whether you’re a professional contractor or an occasional at-home DIYer, there’s a good chance that you’ve had to drill into wood countless times. After all, many projects require you to drill into wood, typically with a standard twist drill bit.

But those standard drill bits suffer from one noteworthy problem – their diameters are fairly small. Even the largest twist bit in your set can’t make a very wide bore hole at all. That type of practical shortcoming may well prevent you from taking on certain projects in the first place.

But now, it’s time to change your hesitation about drilling wide, deep holes into wood.

There are at least five ways of accomplishing that task and we’re going to cover them all in this guide. Moreover, this guide will dig into what kind of bits you need for each drilling method, as well as other uses you may find for those same bits during your woodworking projects.

5 Best Ways to Drill Large Holes in Wood

Let’s jump right in and look at the drill bits you should consider if you need holes that your standard bits can’t handle.

Spade Drill Bit

Boring Large Holes with a Spade Bit If you’ve been in the woodworking industry for some time, then you likely already know the first piece of hardware that you need to grab when it comes time to drill a wide hole.

Without a doubt, a spade drill bit is one of the best, most accessible options for more crafters. These bits get the job done effectively, which is why plumbers and electricians who run wire and piping respectively through walls often keep these bits on hand.

Often, these bits will be called “paddle bits” in DIY circles.

Regardless of what they are called, their broad, flat heads do an excellent job when it comes to grinding out a broad bore. On that front, spade drill bit-cut holes can be created with a great level of precision and control. That’s because each spade bit includes a brad point at their center that secures and controls the unit’s downward motion.

As far as cleanliness goes, a spade bit may not be your best option.

These bits tend to leave behind a rougher edge that would need some sanding if it were exposed. At the same time, spade drill bits can only cut vertically due to their head shape. As such, angled bores with a spade drill bit are simply out of the question.

If you think spade bits might help you with your job, make sure to check out my recommendations.

Spade Bit

Hole Saw

Hole Saw As noted, the aforementioned spade drill bit can often be found in a plumber or electrician’s tool kit. However, when it comes to actual use in the field, these hole-drilling professionals are far more likely to use a hole saw.

That’s because hole saws utilize an annular drilling head that is able to cut a hole out of wood without needing to grind the interior “plug” material.

Professionals have a lot of reasons to prefer hole saws beyond their core functionality, too.

For example, the largest hole saws can create impressively large holes of up to a  few inches in diameter. They also use less power, making them an efficient tool to keep on hand. Also, using a hole saw creates far less mess with regards to wood chips because far less wood is being actively ground down during the hole-boring process.

Hole saws are not perfect, of course.

They cannot effectively operate at angles, for example. They also require a bit of extra work after they’ve been used to cut out a hole. Specifically, you’ll need to find a way to remove the wood “plug” from your saw. This can be a challenging process at times, especially if the plug causes any binding across the hole saw’s head.

Also, they can only be used for cutting through-holes.

Drilling Large Holes with a Hole Saw

Self-Feed Drill Bit

Self-Feed Bit Recently, plumbers and electricians have begun to change up their game when it comes to drilling large holes. To be specific, self-feed drill bits are becoming a more common sight in this professional field.

That’s likely because these specialized drill bits combine the best parts of the spade bit and the hole saw. The resulting holes may not be super clean, but they get the job done when it comes time to run wires or piping.

This type of bit’s name may already hint at part of its physical design.

Specifically, you’ll find that these drill bits feature an extended screw tip that extends from the bit’s end. This allows the bit to sink itself into the targeted workpiece and feed itself downward, in turn. As this occurs, the bits wide annular ring tears into the wood’s surface, creating an efficient hole of considerable depth.

That last factor is actually one of the primary reasons self-feed bits are picking up fresh popularity.

Unlike spade bits, self-feed bits can be worked to moderate depth in a thick workpiece. Many hole saws can go deeper on a single pass, but a self-feed bit can easily be used if you are able to work from both sides (see below for more details on how to do that).

Forstner Drill Bit

Forstner Bit As you may already know from experience, not every large hole you need to cut through wood is at a perfectly vertical angle.

On some occasions, you may need to angle your bore at anywhere between 1 and 89 degrees. For those occasions, a Forstner bit will serve you well. These bits are favored by professional woodworkers and they will work efficiently in industrial applications as well, with a little practice.

Apart from being able to work at an angle, Forstner bits are well-known for the quality of their cuts.

To be specific, they can cut very smooth, broad holes in a variety of wood densities. This smooth texture extends to the base of the bore as well, thus saving you the need to sand out that space for an exposed cut.

Traditionally, Forstner drill bits have been used in drill presses. While this only takes advantage of the bit’s vertical capabilities, this implementation allows for the creation of fairly deep and perfectly straight bores.

However, when used in a handheld power drill, these bits can accomplish a comparable level of depth when working at a horizontal angle. So, it is always worthwhile to have one of these bits on hand for those times when your other large hole drilling options fall short.

If this type of bits caught your attention, you can check my recommended sets here. You should also read my comparison of Forstner bits with hole saws and spade bits.

Drilling Using a Forstner Bit

Step Drill Bit

Step Drill Bit Finally, if you are not sure how you’re going to bore out a large hole in your wood workpiece, consider accomplishing this task with a step drill bit.

Admittedly, these drill bits are not very common among DIYers. However, many professionals keep at least one of these conical drill bits on hand. As such, they should be able to step up the size of their hole fairly efficiently when needed.

To that end, a step drill bit is by far the best option for expanding a small hole into a large hole. While they can’t bore to great depths, they do excel at cleaning out material during the drilling process. This means that the resulting hole comes out fairly clean.

These bits aren’t really intended for angled work. That being said, you may still be able to do so if you have a pre-made angled starter hole available.

You can check out my step drill bit recommendations here.

What If My Drill Bit Is Not Long Enough?

One problem that professionals and amateurs alike run into while drilling large holes involves depth. To be specific, they face the problem of having a drill bit that is not long enough to make the depth of bore that they need.

There are some viable solutions when this impasse occurs, so consider the following carefully.

First, look into extensions for your drill bit. Though these aren’t available for all types of bits, those used to cut large holes are sometimes compatible in this way. This is especially true of the hole saw, which offers extensions that fit many head sizes.

However, if an extension option is not available to you, you’ll need to plan out your through cut carefully.

In fact, you’ll want to work from both ends in order to cut a hole that is connected and properly angled. Often, this can be done by cutting an initial hole with a standard drill bit. After that, any large hole cuts that you end up making from both ends can be centered using that guide hole.

Summary

All in all, you have a fair number of options in front of you when your construction or woodworking project calls for cutting large holes through wood.

Indeed, you have drill bit-based options that can cut for depth, cut with clean edges, and even cut at angles. Now, all you need to do is determine which best suits the needs of your upcoming project.

You may even consider keeping one of each on hand so that you can maximize your team’s functional flexibility.