Choosing a Mortise Attachment for JET Drill Press That Fits the Work and the Table

A JET drill press is a serious machine, so it is natural to want it doing serious joinery, and mortising is where that thought usually lands. Here is the thing nobody tells you up front: JET does not sell a mortise attachment badged for its drill presses. That is not a problem. A mortising attachment is a near-universal accessory, and the right one bolts onto a JET press and cuts square holes as cleanly as any dedicated setup, provided you match it to your quill and to the work you actually do. This guide is about choosing that attachment so it fits both the machine and the job.

A mortise attachment for a drill press clamps a hollow square chisel to the quill and runs an auger bit inside it. The bit bores out the waste while the chisel’s four sharp corners pare the hole square, so each plunge leaves a clean socket. Chain the sockets and you have a mortise for a mortise-and-tenon joint.

The direct answer for JET owners: buy a universal mortising attachment kit whose bushings match your JET press’s quill, such as the popular 16-speed JET JDP-17, and you are set. Fit is decided by the quill diameter, not the brand on the casting. Match that, confirm you have the quill travel and table room for your stock, and a generic kit turns your JET into a part-time mortiser.

How the attachment works on a JET press

The hollow chisel is a square steel tube, sharpened at the tip, with the auger bit spinning inside it. As you pull the quill down, the bit augers chips up and out through a window in the chisel while the corners slice the round hole square. A cast holder clamps around the JET quill, a fence sets the distance from the edge of your board, and a hold-down keeps the workpiece from lifting when you retract the chisel. On a 16-speed JET you also get the luxury of dialing in a proper low speed, which mortising likes.

Matching it to the work and the table

This is where “fits the work and the table” earns its place in the title. Three checks matter. First, the quill: measure your JET’s quill diameter and pick a kit whose bushings match it, since that collar is what clamps the chisel holder. Second, the depth: your mortise can only go as deep as the quill travels, so tall tenons on thick stock need a press with real stroke. Third, the table: the JET table has to carry the fence, the hold-down, and your board, and you need to be able to raise and reposition the table and lock it solid before you cut. Small parts and a crowded table are a recipe for a crooked mortise.

A kit that fits, plus the chisels that matter

For most JET owners the sensible route is an all-in-one mortising attachment kit that includes the chisel holder, fence, hold-down, and a starter set of chisels and bits in common sizes. It clamps to a standard quill and gets you cutting square holes without hunting for a branded part that does not exist. The honest caveat is the one every basic kit shares: the included chisels cut, but they cut cleaner after a few minutes of honing, and the first setup of the bit-to-chisel gap takes patience. When you want better walls, quality chisels such as a Delta or Grizzly set fit the same holder and are worth buying separately.

Setup that gives clean mortises

Get three things right and a JET press mortises beautifully. Set a small clearance gap, about a coin’s thickness, between the bit and the chisel tip so chips clear without burning. Square the chisel to the fence so a row of holes chains straight. And cut in stages, letting the bit auger the waste out rather than forcing a deep plunge that packs chips and scorches the wood. Back thin stock with scrap, keep the chisel sharp, and lock the table before every cut.

The verdict

You do not need a JET-branded mortise attachment, because there is no such thing and you do not need one. A universal kit that matches your JET’s quill does the job, and JET’s own strength, especially the low speeds on a 16-speed press like the JDP-17, actually makes mortising easier. Choose the attachment by the quill, confirm the depth and table room for your parts, fit good chisels, and set the gap and alignment with care. Do that and your JET cuts joinery as clean as the machine deserves.

FAQ

Does JET make a mortise attachment for its drill presses? No branded attachment. Use a universal mortising attachment kit whose bushings match your JET press’s quill diameter.

How do I know a kit will fit my JET? Measure the quill diameter and match it to the kit’s bushings. That collar is what clamps the chisel holder to the machine.

Will it work on a JET JDP-17? Yes. The 16-speed drive lets you set a proper low mortising speed, and a standard-quill kit clamps right on.

How deep a mortise can I cut? As deep as the quill travels. Thick stock and long tenons need a press with generous quill stroke, or you cut from both faces.

Why is the wood burning? Usually the bit-to-chisel gap is too tight or the chisel is dull. Set a small gap, keep the chisel honed, and cut in stages.

What chisel sizes should I start with? 1/4 and 3/8 inch cover most furniture joinery. Add 1/2 inch for heavier tenons.

References

• Grizzly Industrial, H7789 Mortising Attachment Kit for Drill Presses (bushing sizing and fit): https://www.grizzly.com/products/grizzly-mortising-attachment-kit-for-drill-presses/h7789
• Delta Machinery, 17-003 Professional Mortising Chisel and Bit Set specifications: https://deltamachinery.com/product/17-003-3-8-in-professional-mortising-chisel-and-bit-set/