A drill press is a pretty simple looking machine: just a chuck at the end of a spindle that holds a drill bit and allows it to move up and down while it's spinning. But there are a number of things that can get out of kilter that compromise drilling performance and accuracy. These include issues with the machine's pulleys and drive belt, spindle and chuck and the table and column. Fortunately, it doesn't take a lot of time or effort to do a few basic maintenance tasks that help keep your drill press running smoothly. Unless otherwise specified, all the procedures described in this article should be performed with the drill press unplugged from electrical power.
Clean Things Up
If the outside of your drill press's steel and iron parts are rusty or dirty, clean them off using either a rust remover such as Naval Jelly for heavier rust deposits, or a cleaning solvent/degreaser, for lighter grime.
Use a plastic abrasive pad or steel wool to scrub the surfaces. Wipe all parts dry with a clean rag. To keep the column, table, chuck and other bare metal surfaces from corroding, coat them with a protective spray, such as Bull Frog® Rust Blocker. It's also a great idea to vacuum out any sawdust from the machine's motor and electrical switch boxes.
Lubricate the Drill Chuck
To keep the chuck's jaws operating smoothly essential to proper bit centering apply a little drying lubricant, such as Boeshied T-9®, inside of the chuck: First, turn the chuck's shell until the jaws are fully open and blow the inside clean with a burst of compressed air (wear goggles to keep flying dust out of your eyes). Spray or squirt some lubricant up inside and tighten and loosen the jaws a few times while the excess lube drips out. Wipe off any residue with a clean rag.
Vibration and Belt Wear
A worn belt or bent or out-of-balance pulleys can be a source of annoying noise and vibration. Check the belt by unplugging the drill press, removing the machine's head cover and doing a visual inspection of the belt while rotating it by hand. If it has any cracks, ply separations or lumpy sections, replace it right away. If the belt appears normal, check to make sure its tension is correct. You should just be able to deflect it slightly (about 1/4-inch to 3/8-inch) by pressing in the middle, between the pulleys. If it's too loose or too tight, reset the tension following the directions in your machine's manual (Note: belt tightness on drill presses with mechanical variable speed isn't adjusted this way; consult your machine's manual).
 |
 |
Now, with the head cover still off, plug in the drill press, don a face shield and run the motor on its highest speed. Look carefully at the belt and pulleys: They should run smoothly and not generate significant noise. If the belt oscillates excessively, causing periodic vibration, check its tension again and reset it if necessary. Watch the rim of both pulleys as they spin. If there's a visible wobble, turn the drill press off and unplug it, then make sure the setscrew(s) that secure the pulleys to their shafts are tight. Also do a visual inspection to see if the rims on one or both pulleys are bent. If they are, replace them. If a rumbling or growling sound is coming from the pulleys, the drill press's bearings may be worn or dirty and should be replaced a job best done by a machinery specialist.
Check the Spindle and Chuck
It's good to check your drill press's spindle and quill tube (the shaft that the chuck is mounted on the end of and the column it spins inside of that extends down when you're boring a hole), and its chuck, for looseness. Feed the quill down as far as it will go and lock it down, then grab the chuck and quill tube and try to move them from side to side. If the entire quill tube moves, you may be able to adjust this: On older drill presses, tighten the bolt that joins the two halves of the drill press's head together. On some newer drill presses, there's a small setscrew that rides in a groove on the side of the quill tube. Loosen the locking nut and tighten this screw until the movement is reduced. After either kind of adjustment, check to make sure the spindle and quill tube still move up and down smoothly. If it binds, loosen the adjustment a little bit.
If the chuck feels loose on the end of the spindle, retighten or remove and refit it, following the directions in your machine's manual. If your drill press has a chuck that mounts via tapered arbor, carefully clean both the end of the tapered shaft and the socket it fits into with a degreaser such as acetone before remounting the chuck on the spindle.
Checking for Runout
If you've noticed vibration during drilling, this may be caused by the bit turning eccentrically. To check your drill press for runout (wobble), use a standard dial indicator mounted on a magnetic base. Start by chucking up a 2 to 3 inch long piece of 3/8-inch or 1/2-inch diameter drill rod or other straight rod, such as a machinist's transfer punch (that's what I used in the photos). Make sure the rod is centered and tight in the chuck. Now attach the dial indicator's magnetic base to the drill press table and position its plunger parallel to the table with its tip in light contact with the lower end of the rod (see the photo at right). With the drill press unplugged, slowly rotate the belt or pulley while watching the dial. Ideally, it won't move more than a few thousands of an inch as the rod passes through a full rotation.
If the dial moves back and forth (shows runout) more than .003 inches, you have a few possible choices: 1. If the runout is less than .005 inches, you likely can live with it during everyday drilling operations. 2. If it's really excessive (.010 inches or more), you likely need to replace the tool's spindle, quill, and/or possibly the chuck. As these parts are expensive parts and usually need to be replaced by a repair specialist, it might be cheaper to simply buy a new drill press. 3. The third course of action is a procedure recommended by my colleague and machinery expert Robert Vaughan (no, not the Man from U.N.C.L.E.). His technique is to remove as much of the runout and wobble as you can by giving the chuck and spindle a well-placed whack: Start by marking the exact location of the chuck where the dial indicator's plunger is extended the furthest. Wrap the chuck with masking tape and put a pencil mark just above the indicator's plunger (see the photo, below left) Rotate the chuck exactly 180 degrees and add another mark, labeled with an arrow. Now remove the dial indicator, and chuck up the thickest, heaviest steel rod your chuck will hold. Don a pair of safety glasses and give the end of the rod a good solid thwack with a dead blow mallet or other heavy mallet directly below the arrow mark. Recheck runout (as described above) to see if the blow has reduced runout to an acceptable level, and repeat the striking procedure if it's necessary. Just don't strike the steel rod too hard, lest you make the spindle wobble worse.
 |
 |
Set the Table Square
As drill presses are used to drill holes at 90 degrees about 95 percent of the time, it's important that your machine's table sets at exactly 90 degrees relative to the chuck and spindle. You can use the same rod used for checking runout to set the alignment of the table, as long as it extends at least a few inches below the chuck. After chucking the rod, set a good reliable try square on the table and align it perpendicular to the table's mount axis (see the photo, left). Now eyeball the space between the square's leg and the rod, to see if the rod and try square leg are perfectly parallel. Setting a well-lit piece of white cardboard a few inches behind the square will help you see any gaps more easily. Reposition the square on the other side of the rod, with it still perpendicular to the table's mount axis, and look for any gaps here. If there's a slightly angled gap, that means the table is tilted slightly: Loosen the table's tilt locking lever (also remove a locking pin, if your table has one) and tap the table until the rod and square are perfectly aligned. Lock the table down and check again. If your drill press table has a tilt scale, reset the pointer or cursor so that it aligns with the zero degree mark on the scale.
 |
 |
More Table Maintenance
Most modern drill presses have a crank mechanism that raises and lowers the table. If this has become hard to operate, spray the gear and rack with a penetrating lubricant (like WD-40). Dry them off with rags and compressed air, as necessary, then spray them with a drying lubricant (e.g., Boeshield T9). Many drill presses have gear racks that are loosely mounted to the column, to allow the table to be swiveled side to side. If your table is difficult to swivel, make sure the column is clean and free of rust and grime. If the gear rack is difficult to move from side to side, you may need to raise the top collar that secures it. Loosen the collar's setscrew and lift it slightly, then retighten the screw.
Aligning Laser Sights
Some newer drill presses have a pair of built-in lasers. These project a pair of lines that form a crosshair on top of the table, to indicate where the center of the drill chuck is: very convenient for centering a bit on a pencil mark. If the laser crosshair no longer matches the exact drill center of the chuck, it's a simple matter to realign the lasers. First, clamp a scrap of wood to the drill press table and lock the table down. Now chuck up a very small (1/16-inch diameter or less) straight drill bit and bore a small hole in the scrap. Turn the adjusting knob or screw on one of the lasers until its line projects over the drilled hole. Repeat the process with the other laser. Test the alignment by drawing a center mark on a scrap, positioning it with the laser crosshairs and drilling another hole. If the hole matches your mark, you're done. If not, readjust the lasers and test again.
 |
 |
Sandor Nagyszalanczy is a furniture designer/craftsman, writer, photographer and regular contributor to Woodworker's Journal. His books are available at: www.sandorsworkshop.com