Why Should I Predrill Pilot Holes In Wood?

drilling pilot hole in wood

One of the secrets to achieving a strong finished project involves pre-drilling pilot holes in your wood projects. This trick allows you to magically join two pieces of wood without the worry of splitting your board.

Pre-drilling pilot holes will keep your project precise, prevent your wood from splitting, and provide a stronger hold. Pre-drilling a pilot hole might seem like an extra chore; however, it can save you time in the long run if done correctly. 

In this article, we will go over why pre-drilled pilot holes can be so helpful. First, we will discuss why pilot holes are helpful. Then, we will give you a few tips on how to make them properly. 

What’s a Pilot Hole? 

If you’re new to this, a pilot hole is a pre-drilled hole that allows a screw to properly sink into the wood without splitting the board. 

If you’ve never used pilot holes before, we will go over making a good pilot hole near the end of this article. 

First, however, I want to go over a few reasons pilot holes can be so effective with woodworking

7 Reasons Why Pilot Holes Will Improve Your Woodworking 

I’ve compiled a list of reasons why pre-drilling pilot holes will benefit your woodworking. Indeed, there are not many cons to doing this. Yes, there are times when the number of pilot holes you need to drill may seem like a lot; however, the quality you get and the time you save replacing broken boards with be worth it. 

So, here are the major reasons not to skip pilot holes: 

Pilot holes . . .

  1. Reduce the chance of splitting your wood 
  2. Reduce the strain on your drill 
  3. Decrease likelihood of stripped screws 
  4. Improve control and safety when drilling 
  5. Provide a stronger hold 
  6. Eliminate screw ‘wandering’
  7. Look clean and professional 

There’s our wonderful list. Now, let’s see what this all means. 

Pilot Holes Drastically Reduce the Likelihood of Splitting

Cracked wood because of screw

We’ve all been there. You’ve put hours into that project. You’re planning on giving it as a gift to your special friend. You begin to drill the final screw and CRACK. The end of the wood splits, and your heart along with it . . . 

When we drill a screw into a piece of wood, we are displacing some of the wood’s fibers to make room for the screw. Sometimes, this isn’t a problem: other times, the end of the board cracks to relieve the pressure. 

By displacing an amount of wood before drilling the screw, pilot holes practically eliminate this problem. 

Pre-drilled Pilot Holes Reduce the Strain on Your Drill 

Drills operate with differing degrees of torque. If you’re drilling into an especially dense wood, you’re going to need a lot of torque to overcome the wood’s density. 

When you pre-drill a hole, you reduce the strain on your drill, subsequently increasing the life of your drill and your drill’s battery

This reduction in torque also has some other added benefits to pilot holes. We’ll go over these below. 

Predrilled Pilot Holes Prevent Stripping Screws 

There are few things more frustrating in the shop than a stripped screw. Stripping a screw slows you down and also wastes a screw (they can be expensive!). 

When you reduce the amount of torque and speed needed to drive a screw properly, you also greatly reduce the chance of stripping that screw head. 

Even with a properly sized bit, stripping can happen when driving a screw too fast and too hard. Combine too much torque and speed, and your drill bit will “spin-out” – likely stripping the screw head. 

I’ve even seen drill bits crack under too much tension. 

Pre-drilled Holes Increase Safety 

Remember what I just said about drill bits cracking? Well, it turns out this isn’t only inconvenient, it’s very unsafe. 

Not only can pieces of screw or drill bit turn into projectiles, possibly damaging eyes and skin, but there is also the risk of the slipped drill bit driving into our nearby hand.

There have been stories of guys trying to drive a screw when suddenly the drill bit jumps off and the full force of the drill goes into their hand that was stabilizing the board. 

Especially when drilling into a hardwood, like oak or maple, you’re going to want to pre-drill a hole to keep the torque on your drill low. 

This will be smoother and safer. 

Pre-drilling Pilot Holes Will Provide a More Durable Joint 

When properly pre-drilling a pilot hole, you create a much more secure joint in the process. If you want to read a whole article on this, you can click here: I’ve been drilling pilot holes wrong my entire life. 

Otherwise, let me give you a basic explanation below. 

When you connect two boards with a screw without a pilot hole, the screw is essentially working against the board, pushing the two pieces apart. 

However, a proper pilot hole – one where the hole’s diameter on the top board is greater than the threads of the board, allowing the screw head to clamp the board down to the bottom board – you get a stronger, more intuitive hold.

Maybe you’ve looked at some screws and wondered why the portion near the neck didn’t have any threads? Well, that’s to allow for the proper anchor, without those top threads pulling the wood apart. 

I know this isn’t easy to visualize. Here’s a video on proper pilot holes that will explain everything. 

Pilot Holes Will Eliminate ‘Wandering Screw’ 

If you’ve ever tried to drive a screw into a hard piece of wood, you know that there can be a tendency for the screw to ‘skate away,’ sort of like a figure skater spinning on the ice. 

When this wandering happens, it throws off your precision and potentially damages your final project. 

Even if you start your screw where you want it, sometimes it’s hard to keep your screw going straight into the board. Who knows, maybe there’s a hidden knot in there, or perhaps the wood density causes a change in the direction of the screw. 

Either of those things is bad. If you get a screw going on the wrong course, it can be very difficult to correct. Many times, you will need to start with a whole new piece of wood, which can be problematic if you were building something with expensive hardwood. 

Take the extra step and drill a good pilot hole. The pilot hole will allow you to keep your screw going straight into the wood. This will give you a stronger hold, look nicer, and save you time and money in the long run. 

Pilot Holes Keep Your Project Looking Clean and Professional 

No doubt, many expert craftsmen prefer to use non-screw joints, like the dovetail. However, there are times when a screw or nail is your only good option. In this case, a pilot hole will help you make the best of the situation. 

A good pilot hole will have a portion of the hole sunk-in to hide the screw’s head. This sink-hole portion will also allow you to disguise the screw heads with caps or wood filler if you desire. 

Three Steps to Drill a Better Pilot Hole Into Wood 

We will now give you three steps to drill a better pilot hole. 

  1. Use two drills 
  2. Keep the pilot hole about the size of the root of the screw
  3. Make the hole on the top board larger than the full diameter of the screw


Use Two Drills to Make Pilot Holes Faster 

Yes, pilot holes can take some time. However, they don’t have to put the brakes on your project. 

If you have two drills in your shop, fit one with the bit for the screw and one with the bit for pre-drilling. This will especially help if you have a second person to help you. One of you can pre-drill, the other can follow with the screw. 

Like a highly efficient factory! 

Keep the Pilot Hole about the Size of the Root of the Screw 

Imagine the screw is a tree, and the threads are the branches. The trunk of the tree is in the middle. You want your pre-drilled holes to be about the same diameter as the middle, or trunk, of the screw. 

This ensures you don’t split the board, but you still get a strong bit from the threads of the screw. For softwood, the hole can be a bit smaller, for hardwood, you want the hole slightly larger.

Make the Pilot Hole on the Top Board Larger than the Bottom 

So I just told you to pre-drill a hole the size of the root of the screw; however, you may get an even stronger hole by boring the hole of the top board a little bit larger than the bottom. 

This will ensure that your screws clamp that top board down with maximum force. 

They make special drill bits that will bore a hole with two diameters – larger on top, smaller at the bottom. However, this is yet another way you could take advantage of having two drills. Use one to drill the long skinny hole and the other increase the diameter at the top of the pilot hole. 

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