Aug 04, 2020

How to Enlarge a Hole in Wood without Ruining Your Project

how to enlarge a hole

To the non-DIYer, dedicating an entire blog post to this process may seem like overkill. But anyone who wields their cordless drill on the regular can attest: the issue of making an existing hole larger comes up all. the. time. Whether repairing something around the house, replacing a part or piece of hardware, or just because you didn't quite get it right the first time, any maker, woodworker, or generally handy person knows how frequently one needs to enlarge a hole, and how surprisingly difficult it can be to pull off. 


The problem is: a drill bit cuts by rotation. And in order to make a nice round hole, the center of the bit requires a place to register, so it can spin evenly. When there's already a hole, there's nowhere for the center of the bit to bite into. 

And, you can imagine what happens: the spinning bit will wander around, looking for a place to land. This can, at minimum, provide a raggedy edge, and at worse, tear up the surround surface of your workpiece. 

So what to do to enlarge a hole? They actually make tools designed to do this called step drill bits. They work fairly well for certain applications, though not all, and if you have one, you probably already know this. But if you're in the midst of a project and the store is closed and you don't want to wait two days to order one online, there are several other ways to go. 

Here are several approaches on how to enlarge a hole without messing up the surrounding surface. And while the photos here are of some simple unattached boards, the good news is: several of these approaches will work with an assembled project, structure, cabinet, and the like.

how to enlarge a hole

Use a Drilling Guide

If you have one, a drilling guide will help keep the bit from spinning out. A  guide like Milescraft Drill Block only costs around $8, and has countless uses. The solid edges prevent the bit from wandering, allowing you to bite into the surrounding material . You'll want to clamp both the work and block securely to keep everything aligned.

Potential Drawback: Of course you'll only be able to size your hole to 1/16" or even 1/8" increments, so this won't work when you need just a bit more space.

how to enlarge a hole

Ream It Out

A tapered reamer can help you easily enlarge a hole in wood, metal, or plastic. Designed to help de-burr metal, this is conical tool with several cutting edges, and can be had anywhere for well under $10. You simply insert and twist, and it will cleanly and easily remove material.


how to enlarge a hole

Potential Drawback: Of course, a tapered tool will produce a tapered hole. If you simply need a clearance hole for a bolt or a screw, this is totally fine — you just need to make space for the hardware to pass through. But know that your holes won't have straight sides, and this will be increased with the material's thickness. But it works great. 


how to enlarge a hole

Rasp Away

Similar to the reamer, a round rasp will help you remove material from the inside. You'll have a hard time making the new hole perfectly round, but if its covered with a washer or the head of a bolt or screw, this wont really matter. If you dont have a round rasp, a length of threaded rod works great in a pinch. 

Potential Drawback: Using a rasp will require access to both sides, or at least clearance behind. The new hole will not be even all the way around.


how to enlarge a hole

Reverse Drilling (My Favorite Way)

I find this to be the most versatile solution and my go-to approach to enlarge a hole. It works like this: 

Chuck in the next larger bit into your drill. Then, flip the drill into reverse mode using the button above the trigger. With the drill turning counterclockwise, it greatly reduces the chance that the cutting edges of the bit will bite into the wood and cause tearout or scarring.


how to enlarge a holeEssentially, you're actually using the flutes of a drill bit like a rasp, slowing removing wood to make an exact sized hole.

This is a great solution when the area will be visible. I use this all the time when I work on upgrading parts in my electric guitars. Reverse drilling allows me to increase the existing hole for new pots or tuners, without damaging the finished surface of the instrument.


how to enlarge a hole

The results look about as good as you can hope for when widening an existing hole. Give it a shot. 


how to enlarge a hole

Make a Wood Sandwich

Here's one final solution that works well when making large holes. It's a great approach if you, say, need to use a hole saw to make a space for a new knob and a handle. 

A hole saw uses a pilot bit to register itself. When there's an existing hole, there's nowhere for that to cut into. So, give it somewhere to attach by adding wood to each side of your work surface. A thin piece of plywood or luan is fine. Really, any scrap will work, but you'll have to cut through it entirely, so choose something thin but sturdy.

how to enlarge a hole

Clamp everything securely, and then insert the pilot bit on your mark. As you drill, the pilot bit is captured by both outer pieces of wood, so when it starts to score the workpiece, it's stable. It also helps to protect the surface in case the saw does skitter a bit, and helps to prevent tearout on the back side. For best results, you can also use the pilot bit hole to drill in from the other side.

These are some of my favorite ways to enlarge a hole. How have you dealt with this problem in the past? Please post your solutions in the comments below.



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Dan on Jul 30, 2020:

So glad to have found this! I need to slightly enlarge three of the four pot holes in an old PRS SE 245 guitar and it sounds like the reverse drill trick will work!

Can someone tell me if the hole should be drilled from the top (finished side) or the bottom (from inside the cavity)? Or does it matter?


PeterS on Jul 13, 2020:

Just ran into this problem with a used door. The hole for the latch mechanism is too small for the latch I want to use (7/8" hole vs 15/16" mechanism)
I purchased a 7/8" softwood dowel. Glued in place, now redrill centering the bit in the dowel

Christina Lindsay on Mar 22, 2020:

Is there a way to make it look nice if that second hole in the first photo happens? It’s a 1-1/8 hole, so fairly large but looks pretty unsightly. How do I make it look nice and presentable after I failed at these methods of making it look nice when expanding? Thanks!

Hackos on Feb 24, 2020:

You would not believe I was looking for a solution to enlarge tuner holes on electric guitar. Thanks!

Phil Lacio on Jan 24, 2020:

This is a useful tool when using a hole saw:
Starrett KA19-N"Oops" Arbor, Hole Enlargement Arbor

AAT on Jan 05, 2020:

Thanks, the reverse drill trick worked a treat for me: I enlarged an 8mm pot hole to become a 12mm switch hole with no damage done to the finish of my guitar.

Les Garten on Apr 10, 2019:

Thanx! I came here looking for info on how to ream out a hole for an upgraded guitar tuner! Reason I was looking for this was because I didn't want a tapered hole from a reamer and I was afraid to hit it with a drill. Your description of everything seemed to be custom made for me!