Choosing a Drill Press Mortiser Attachment That Fits the Work and the Table

All Posts benchtop drill presses Noah Carter Last updated on July 20, 2026

If you’ve ever tried to cut a mortise with a router jig and ended up with walls that look like you were holding the tool in your teeth, you already know why a mortising attachment exists. The hollow chisel mortiser attachment for drill press is one of those tools that turns a frustrating operation into something almost pleasant - but setup details matter more than most sellers bother to tell you.

What a Drill Press Mortiser Attachment Actually Does

A mortiser attachment converts your drill press into a hollow chisel mortiser. A square steel chisel surrounds a rotating auger bit. When you plunge the quill, the auger clears the bulk of the waste and the chisel squares the corners simultaneously. The result is a clean, square-sided mortise ready for a tenon.

The attachment clamps around your drill press quill housing using a column collar and a series of interchangeable bushings to match your specific quill diameter. A cast-iron chisel holder hangs below the collar. A fence and hold-down assembly register the workpiece.

Which Drill Presses Host the Attachment Well

Quill diameter: All four kits below ship with multiple bushings spanning a range of quill ODs. Most 12-17-inch benchtop drill presses land in the 1.88-2.60-inch quill OD range. Measure your quill OD before you order.

Quill stroke: A typical mortise runs 3/4 to 1 inch deep. Most drill presses offer at least 2.5 inches of spindle travel.

Good hosts: The JET JDP-17M floor model, Shop Fox W1680 and M1039 benchtop presses (adequate for occasional use), the Delta 11-990 benchtop (limit to 3/8-inch chisel).

Avoid: The Grizzly G0485 oscillating spindle sander/drill press - its quill geometry doesn’t adapt cleanly.

The Four Kits Worth Considering

Grizzly Industrial H7789 Mortising Attachment Kit

Grizzly Industrial H7789 - Mortising Attachment Kit

Three two-piece mounting sleeves, three split bushings covering quill ODs from 1.57” to 2.945”. Four chisels (1/4, 5/16, 3/8, and 1/2 inch) included. Cast-iron chisel holder.

What works well: Bushing range covers most 12-17-inch drill presses. The alignment pin is genuinely useful - don’t skip it.

What doesn’t: The fence hold-down T-nuts can loosen under vibration. Use thread locker on them. Expect 30-45 minutes on the first setup.

Best fit: Most benchtop and floor drill presses in the 12-17-inch range.

Shop Fox D4031 Mortising Attachment Kit

Woodstock D4031 Mortising Attachment Kit

Nearly identical to the H7789 in scope and specification. Same bushing count, same chisel sizes, same cast-iron holder. Both from Woodstock International. If one is in stock, the other is a like-for-like substitute.

Best fit: Identical to the H7789. Choose whichever is available.

VEVOR Mortising Attachment for Drill Press

Five bushings covering 2.09” to 2.56” quill ODs. Four chisels included.

What works well: Slightly wider bushing range steps. Costs less than H7789 or D4031.

What doesn’t: Fence assembly is less substantial. Under repeated use with a 1/2-inch chisel in hard maple, you’ll notice flex. Better for softwood and regular hardwoods.

YUEWO Mortising Attachment for Drill Press

Cast iron and steel construction. Emphasizes easy installation and disassembly - useful if you share a drill press between mortising and regular drilling.

What works well: Faster to dismount than the H7789. Chisels available separately.

What doesn’t: Sparse documentation. Watch an installation video before opening the box.

Comparison Table

Kit	Chisels	Bushing Range	Fence Quality	Best For
Grizzly H7789	4 (1/4-1/2”)	1.57-2.60” OD	Solid cast iron	Most drill presses
Shop Fox D4031	4 (1/4-1/2”)	1.57-2.60” OD	Solid cast iron	Same as H7789
VEVOR	4 (1/4-1/2”)	2.09-2.56” OD	Adequate	Budget builds
YUEWO	4 (1/4-1/2”)	2.09-2.56” OD	Adequate	Frequent swap users

Drill Press vs. Dedicated Mortiser: The Honest Answer

Choose the drill press attachment if: You cut mortises occasionally, already own a quality 12-17-inch drill press, or shop space rules out another dedicated machine.

Choose a dedicated mortiser if: You’re cutting mortises in volume - chair legs, frame-and-panel work, production furniture - and want a fence that stays put without fuss.

Tips for Better Results

Chisel alignment is everything. Use the alignment pin before tightening anything.
Wax the chisel. A light coat of paste wax reduces friction dramatically.
Plunge in overlapping passes. Offset each plunge by about 70% of the chisel width.
Secure your workpiece. A 4-inch drill press vise or hold-down clamp is required.

FAQ

Can I use a mortising attachment on any drill press? No. Measure your quill’s outer diameter first and confirm it falls within the bushing range of the kit you’re considering.

What is the best mortiser bit for drill press use? The 3/8-inch size is the most useful starting point. It suits mortises for door frames, small furniture rails, and general joinery.

What is the difference between the Grizzly H7789 and the Shop Fox D4031? Functionally, very little. Both from Woodstock International. Buy whichever is available at the better price.

References

Grizzly H7789 instruction sheet: cdn0.grizzly.com
Shop Fox D4031 manual: cdn0.grizzly.com