How to Change the Chuck on a Guardian Power Drill Press BDM-58-5S

The Guardian Power BDM-58-5S is one of those imported benchtop presses that turns up under several names, and owners often go looking for parts by the model number stamped on the casting. When the chuck wobbles, drops bits, or needs upgrading, changing it is well within reach, but the BDM-58-5S shares a trait with its many cousins: details like the retaining screw and taper are not always documented, so you confirm them on the machine rather than trusting a spec sheet. Learning how to change the chuck on a Guardian Power drill press BDM-58-5S is really a lesson in checking your specific press before you tap anything.

Changing the chuck means separating the old chuck from the spindle and seating a new one. On presses of this type the chuck sits on a Jacobs taper arbor, and that arbor seats in the spindle on a Morse taper. Many small imports add an internal retaining screw.

The direct answer: unplug the press, check for and remove any internal retaining screw, then drive the old chuck off its taper with wedges (or knock the arbor out with a taper drift), and seat the new chuck on clean, dry tapers. Because parts data for the BDM-58-5S is thin, confirm the taper by measuring before ordering a replacement.

Confirm your specific machine

With the press unplugged:

• Open the jaws fully and look down the bore for a retaining set screw. Small imports like this often have one, and it is frequently reverse threaded, so it may loosen clockwise. Remove it first.
• Find the spindle access slot by feeding the quill down, where a taper drift can drive the arbor out.
• Measure the tapers if you plan to fit a new chuck, since documented specs for the BDM-58-5S are scarce. A common pairing is a JT33 chuck taper and an MT2 spindle taper, but measure to be sure.

Removing the old chuck

1. Open the jaws fully.
2. Slide drill chuck removal wedges into the gap between the chuck and the arbor collar, one each side.
3. Tap them evenly, alternating sides, until the chuck releases square. Support it so it does not drop.
4. To remove the arbor from the spindle instead, feed the quill down and drive a taper drift through the slot with a soft dead blow mallet.

Fitting the new chuck

1. Wipe both tapers bone dry. No oil on a friction fit.
2. Seat the arbor into the spindle with one firm push.
3. Seat the new chuck onto the arbor with a straight axial push against a wood block.
4. A matched replacement drill chuck with JT33 arbor sized to your measured taper takes the guesswork out.
5. Indicate a straight pin to confirm it runs true.

Where people go wrong

The first mistake is assuming the BDM-58-5S matches some other press and skipping the retaining screw check, then hammering a chuck that is still bolted on. The second is ordering a chuck by guess when the taper was never confirmed by measuring. The third is oiling the taper on the new chuck, which lets it creep off under load.

The verdict

Changing the chuck on a Guardian Power BDM-58-5S is straightforward as long as you treat it as the unbadged import it is: check your specific machine rather than a spec sheet. Look for the retaining screw, measure the taper, pull the old chuck with wedges, and seat the new one on clean, dry tapers. Confirm with an indicator. Do that and this common benchtop press drills true again, whatever name is on the label.

Three takeaways:

1. Check your specific BDM-58-5S; parts data for it is thin.
2. Remove any internal retaining screw before driving the chuck.
3. Measure the taper before ordering, and seat the new chuck dry.

FAQ

How do I change the chuck on a Guardian Power BDM-58-5S? Unplug it, remove any internal retaining screw, drive the old chuck off with wedges, then seat a new chuck on clean, dry tapers. Confirm the taper by measuring first.

Does the BDM-58-5S have a retaining screw? Many small imports like it do. Open the jaws fully and look down the bore. A screw at the bottom is a retaining set screw, often reverse threaded, and must come out first.

What taper does it use? A common pairing on this type is a JT33 chuck taper and an MT2 spindle taper, but documented specs are scarce, so measure yours before buying a replacement.

Why is parts information so hard to find? The BDM-58-5S is an imported press sold under several names, so consistent parts data is thin. Confirm details on your actual machine.

Can I just hammer the old chuck off? No. Never strike the chuck body. Use wedges or a taper drift with even, axial taps to avoid denting the chuck or bending the arbor.

How do I make the new chuck run true? Seat it on clean, dry tapers with one straight push, never oiled, then indicate a straight pin. A few thousandths of runout is normal.

Will the arbor fall when it releases? Yes. The Morse taper lets go suddenly, so support or catch the arbor and chuck so they do not drop.

References

1. Zoro Resource Hub, Morse vs. Jacobs Tapers. https://www.zoro.com/resourcehub/what-are-the-dimensions-and-angles-of-morse-tapers-and-jacobs-tapers/
2. Occupational Safety and Health Administration, Woodworking eTool: Drill Presses. https://www.osha.gov/etools/woodworking/production/machines-tools/drill-press