Getting Choosing a Replacement Arbor for a Drill Press Right: Fit, Tools, and Final Checks

The arbor is the small adapter that decides whether your chuck even fits your spindle, and choosing the wrong one is the most common reason a new chuck will not seat. Choosing a replacement arbor for a drill press is simple once you know the two tapers it has to match, and getting that match right is what makes the chuck run true instead of wobbling.

An arbor is a hardened steel adapter with a Morse taper on one end that seats in the spindle and a Jacobs taper on the other end that carries the chuck. Choosing a replacement means matching the Morse taper to your spindle and the Jacobs taper to your chuck, so the two ends fit both machine and chuck exactly.

Short answer: identify your spindle’s Morse taper (MT2 is the most common on benchtop presses) and your chuck’s Jacobs taper (usually JT33), then pick an arbor that matches both, such as an MT2 to JT33 arbor, and seat it on clean, dry surfaces.

Fit: match both tapers

1. Spindle taper. Most benchtop presses use MT2; larger ones use MT3 or MT4. Check your manual or measure.
2. Chuck taper. Most drill chucks use JT33, but smaller chucks use JT6 or JT2. Read the chuck’s marking.
3. Both must match. An arbor only works if its Morse end fits your spindle and its Jacobs end fits your chuck, for example a 3MT-33JT arbor for an MT3 spindle and a 33JT chuck.
4. Drift tang. Choose an arbor with a tang if your spindle slot uses one to knock the arbor out.

The arbor to fit

For the common benchtop combination, a heavy-duty MT2 x JT33 arbor matches an MT2 spindle to a JT33 chuck, which covers most Harbor Freight, Delta, and similar presses. Confirm your spindle is MT2 and your chuck is JT33 before ordering.

The honest drawback: an arbor is a permanent partner to the chuck once seated, so pressing them apart later is a chore. Who should skip a separate arbor: anyone whose press has a JT33 spindle stub that takes a JT33 chuck directly, with no arbor needed.

Final checks

1. Morse taper matches the spindle.
2. Jacobs taper matches the chuck.
3. Tang present if your spindle slot needs one.
4. All tapers cleaned dry and bright, no oil.
5. Chuck runs true, checked with a straight bit before use.

Match both ends, seat it clean

Choosing a replacement arbor is a matching exercise: the Morse end to the spindle, the Jacobs end to the chuck. Get both right, seat on clean dry tapers, and the chuck runs true. Guess one end and nothing fits.

Three takeaways:

• Match the Morse taper to the spindle and the Jacobs taper to the chuck.
• MT2 to JT33 covers most benchtop presses, but confirm both ends.
• Seat on clean, dry tapers and check runout with a straight bit.

FAQ

What is a drill press arbor? A hardened adapter with a Morse taper that seats in the spindle and a Jacobs taper that holds the chuck, letting a Jacobs-taper chuck mount on a Morse-taper spindle.

How do I know which arbor to choose? Match your spindle’s Morse taper, often MT2, to your chuck’s Jacobs taper, often JT33. The arbor must fit both, such as an MT2 to JT33.

What is the most common arbor size? MT2 to JT33 is the most common on benchtop presses, but larger machines use MT3 or MT4, and small chucks use JT6 or JT2.

Do I need an arbor at all? Not always. Some small presses have a JT33 spindle stub that takes a JT33 chuck directly. An arbor is needed only to bridge a Morse-taper spindle to a Jacobs-taper chuck.

What is the tang for? The tang lets a drift key knock the arbor out of a slotted spindle. Choose an arbor with a tang if your spindle slot uses one.

Why does my chuck wobble on a new arbor? Usually a dirty taper or a mismatched pairing. Clean all surfaces, confirm both tapers match, and reseat before checking runout.

References

• Grizzly Support, drill chucks and arbors guide: https://support.grizzly.com/hc/en-us/articles/4412902171415-How-to-drill-chucks-arbors-101
• Victor Machinery, drill chuck mounting and arbor selection reference: https://www.victornet.com/reference/Drill_Chuck_Mounting.html