Can You Use a Drill Press as a Mortiser? Capability, Limits, and the Safer Setup
This is the one machine-swap question where the answer is genuinely yes, with a catch. Unlike using a drill press as a router or lathe, turning it into a mortiser is a real, supported thing: manufacturers sell attachment kits made for exactly this, and generations of woodworkers have cut mortises this way. The catch is that a drill press mortising setup is slower and fussier than a dedicated mortiser, and it only works if your press meets a few requirements. Knowing those upfront is the difference between clean square holes and a frustrating afternoon.
Yes, you can use a drill press as a mortiser with a mortising attachment kit, which adds a hollow square chisel and an auger bit plus a fence and hold-down. The chisel squares the round hole the bit drills, producing the square-walled mortises for mortise-and-tenon joints. It works well for light and occasional mortising, though it is slower and less rigid than a dedicated mortising machine.
How a mortising attachment works
The clever part is the hollow square chisel. Inside it spins an auger bit that drills a round hole, while the four-sided chisel around it pares the corners square as it is pushed down. The result is a square hole. Line up several of these and you have a mortise. A kit such as a drill press mortising attachment supplies the chisels and bits in common widths plus the bushings, fence, and hold-down that clamp to the press, which is why makers like Grizzly sell dedicated kits for the purpose.
What your drill press needs
The attachment only works if the machine can accept it, so check three things.
Quill diameter. Mortising attachments clamp around the quill, and kits include bushings for common quill sizes. Confirm your press matches a bushing in the kit.
Enough travel and power. Driving a chisel through hardwood takes force and stroke. A very light benchtop press may struggle, while a sturdier machine handles it comfortably.
Rigidity and a solid table. The hold-down and fence need something firm to work against. A flexy press or wobbly table makes for wandering, out-of-square mortises.
Drill press mortising versus a dedicated mortiser
| Factor | Drill press plus attachment | Dedicated mortiser |
|---|---|---|
| Setup | Add and align the attachment | Ready to go |
| Force to the chisel | Standard feed handle | Long lever built for chisels |
| Rigidity | Depends on the press | Purpose-built, stiff |
| Speed of work | Slower, fussier | Faster, smoother |
| Best for | Light, occasional mortises | Frequent or production mortising |
Setting it up safely
Mount the attachment squarely so the chisel faces align with the fence, or your mortise walls will not be straight. Keep the chisel and bit sharp and properly gapped, a common setup detail, so the bit does not overheat and the chisel pares cleanly. Clamp the workpiece with the hold-down and never freehand it, and clear chips as you go. The usual drill press safety from CCOHS still applies: secure the work, protect your eyes, and let things stop before clearing waste. Because mortising loads the quill downward, it is far kinder to the machine than routing or turning, which is why this swap is legitimate where those are not.
When to buy a real mortiser
The tell, as always, is volume. For a few mortises on an occasional project, the attachment is a smart, economical choice. If you cut mortises often, or in tough hardwood, a dedicated benchtop mortiser with its long lever and purpose-built rigidity will be faster, cleaner, and less fiddly. The attachment proves the concept, a dedicated machine industrializes it.
The verdict
Yes, a drill press can genuinely serve as a mortiser with the right attachment kit, using a hollow square chisel around an auger bit to cut square-walled mortises, and unlike routing or turning it loads the quill downward the way the machine likes. It works best for light, occasional work on a press with a matching quill size, enough power and travel, and solid rigidity. Three takeaways: the hollow chisel is what squares the drilled hole, check quill diameter, power, and rigidity before buying a kit, and step up to a dedicated mortiser when you cut mortises often or in hardwood. Who is this ideal for? Occasional furniture makers who want mortise-and-tenon joints without buying another machine.
Frequently asked questions
Can you use a drill press as a mortiser? Yes, with a mortising attachment kit. It adds a hollow square chisel around an auger bit plus a fence and hold-down, letting the press cut the square-walled holes that make up a mortise. It suits light, occasional work.
How does a mortising attachment make square holes? An auger bit spins inside a hollow four-sided chisel. The bit drills a round hole while the chisel pares the corners square as it is pressed down, leaving a square hole.
What do I need to check on my drill press first? That its quill diameter matches a bushing in the kit, that it has enough power and spindle travel to drive a chisel through hardwood, and that the machine and table are rigid enough for the hold-down and fence.
Is a drill press mortiser as good as a dedicated one? For light, occasional mortises, it works well and saves money. A dedicated mortiser has a long lever and purpose-built rigidity, so it is faster, cleaner, and less fussy for frequent or hardwood work.
Why is mortising okay on a drill press when routing isn’t? Mortising pushes the chisel straight down, loading the quill the way it is designed for. Routing and turning apply sideways loads the bearings and chuck are not built to take.
Do I need to sharpen or gap the chisel and bit? Yes. Keeping the chisel sharp and the bit correctly gapped inside it prevents overheating and gives clean, square walls. It is a key setup step for good results.
How do I keep mortises square and aligned? Mount the attachment so the chisel faces align with the fence, clamp the work with the hold-down, and index each cut along the fence. Careful alignment is what keeps the walls straight.
References
- Grizzly, Mortising Attachment Kit for Drill Presses (H7789). https://www.grizzly.com/products/grizzly-mortising-attachment-kit-for-drill-presses/h7789
- CCOHS, Metalworking Machines: Drill Presses. https://www.ccohs.ca/oshanswers/safety_haz/metalworking/drillpresses.html
- Pro Tool Reviews, How to Use and Set Up a Drill Press. https://www.protoolreviews.com/how-to-use-drill-press/
