How to Rout Large, Custom-Sized Holes in Wood
Making a large-diameter hole in wood usually means reaching for a drill press and a hole saw or Forstner bit. But what happens when you need a hole that's larger than your bits can handle—or an odd size that doesn't match any of them?
And what if the workpiece is too large to fit on your drill press?
That's when I turn to my router.
With a simple router circle-cutting jig, a straight bit, and a pattern bit, you can create smooth, accurately sized holes without investing in an assortment of specialty drill bits.
The trick is to use the router to establish the hole's exact diameter, remove most of the waste with a jigsaw, and then make a final cleanup pass with the router.
It's a straightforward technique that works well for large openings in plywood and other woodworking projects.
Why Use a Router to Cut Large Holes?
Hole saws and Forstner bits are convenient for making holes in wood, but they have limitations.
A hole saw cuts a fixed diameter, so you need a different saw for each size. Large Forstner bits can be expensive, and using them often requires a drill press with adequate capacity.
A router offers more flexibility.
By adjusting the pivot point of a circle-cutting jig, you can make a hole to virtually any diameter within the jig's range.
You also don't need to position a large workpiece beneath a drill press.
Instead, you bring the router to the workpiece.
Make a Simple Router Circle-Cutting Jig
The first step is making a circle-cutting jig for your router.
This doesn't have to be complicated.
I use a simple auxiliary baseplate that attaches to the bottom of the router with double-sided tape. A small brad serves as the pivot pin.
Install a 1/2"-diameter straight bit in the router.
The important measurement is the distance from the pivot pin to the outside cutting edge of the bit.
That distance should equal the radius of the finished hole.
For example, if you want to make a 6"-diameter hole, the distance from the pivot pin to the outside edge of the bit should be 3".
Take a little time to check the setup before cutting the actual workpiece.
A few test cuts in scrap material will help you dial in the exact diameter.
Shop Tip: Make sure the auxiliary baseplate is securely attached and the pivot pin cannot shift during routing. The jig needs to remain stable throughout the cut.
How to Cut a Large Hole with a Router
Rather than using the router to remove all the material inside the circle, I use a three-step approach.
First, rout a shallow circular groove. Then remove the waste with a jigsaw. Finally, use a pattern bit to trim the edge smooth.
This approach is faster than routing away the entire opening and produces a clean, accurately sized hole.
Step 1: Rout a Circular Groove
Start by marking the centerpoint of the hole on your workpiece.
Drill a small hole at that location to accept the jig's pivot pin.
Position the router so the pivot pin fits into the center hole.
With the straight bit installed and the jig adjusted to the desired radius, rout a circular groove approximately 1/4" deep.
The groove establishes the exact outside boundary of the finished opening.
There's no need to rout all the way through the workpiece at this stage.
The goal is simply to create an accurate circular reference for the remaining steps.
Step 2: Remove the Waste with a Jigsaw
Once the circular groove is complete, it's time to remove the waste material.
Use a jigsaw to cut away the center of the opening.
The routed groove provides a convenient reference to follow as you make the cut.
Keep the jigsaw blade slightly inside the finished edge, leaving a small amount of material for the router to remove.
You don't need to make a perfectly smooth cut with the jigsaw.
The final routing pass will take care of that.
Step 3: Clean Up the Hole with a Pattern Bit
After removing the waste, replace the straight bit with a pattern-routing bit.
The bearing follows the accurately routed circular groove, allowing the cutting edges to trim the remaining material flush with the established diameter.
Work carefully around the opening, allowing the bearing to guide the cut.
The result is a smooth, accurately sized hole without the rough edges that can be left by a jigsaw.
For thicker workpieces, make sure the bearing can register against the routed groove and that the bit has sufficient cutting length for the material.
Tips for Routing Accurate Circular Holes
A few simple precautions will help you get better results.
Secure the workpiece. Make sure the board or panel is firmly supported and cannot shift during routing.
Check the jig's radius. Measure from the pivot point to the outside cutting edge of the straight bit, not the center of the bit.
Make a test cut. A test cut in scrap material helps confirm the finished diameter before you begin working on your project.
Leave material for cleanup. When using the jigsaw, stay inside the routed groove so the pattern bit has a small amount of waste to remove.
Take light routing passes. Avoid forcing the router or removing too much material at once.
Support the waste. When cutting through a large panel, support the center waste piece so it doesn't break free unexpectedly or bind the jigsaw blade.
A Simple Way to Make Custom-Sized Holes
You don't need a large collection of hole saws or expensive Forstner bits to make accurate circular openings.
A router, simple circle-cutting jig, and jigsaw can handle a wide range of hole sizes.
By routing the circular groove first, you establish an accurate boundary. The jigsaw removes most of the waste, and a pattern bit produces the final smooth edge.
It's an easy technique to keep in mind the next time you need a large or custom-sized hole in a woodworking project.
Build a Small Parts Router Table Sled
Routing small parts can be tricky, especially when your fingers end up too close to the bit. This easy-to-build router table sled uses adjustable blocks and a toggle clamp to hold workpieces securely, giving you better control while keeping your hands farther from the cutting area.
BUILD THE ROUTING SLED → A Safer Way to Rout Small Workpieces
