This is my first Instructable, so please bear with me. Constructive criticism is welcomed!
Sometimes I need to drill a perfectly straight hole in surfaces too large for my little bench-top drill press. So I went about modifying my cheap (~$70-ish) drill press from a "bench tool" to a "hand tool." The mod allows me to make holes at a perfect right-angle to large or mounted surfaces like table-tops, floors, and shelves. It is also reversible, so I can convert it to a regular drill press again without any trouble. Best of all, it was free.
Step 1: Get Your Stuff
Tools you will need include...
- Things for disassembling the drill press. These may vary depending on who made your drill press.
- A few screwdrivers.
- Hex wrenches. The only size I needed was 5/32".
- A 1/8" pin punch (or a nail with the tip cut off).
- A hammer. The type doesn't really matter.
- Some method of applying a layer of ink/paint to a palm-sized area on metal.
- I used a Sharpie Magnum. Love those things.
- You could also use spray paint, Dykem layout fluid, regular-sized Sharpies, etc.
- Things for making a big hole in sheet metal. Specifically, a hole slightly larger than the column of your drill press.
- The Messy Way
- A file. Round or half-round files are probably best. A Dremel with a grinding attachment works even better.
- A hand drill .
- Standard twist drill bits.
- The Better Way
- A hand drill.
- A hole saw slightly larger in diameter than the column of your drill press. Mine is a bit over 1-13/16" diameter, so the closest hole saw size I would be able to find would probably be something like 2"
- The Messy Way
Oh, and you'll need a drill press, too.
Step 2: Get Safe
Take your drill press off whatever table it may be on. Unplug it. Take off any attachments that are on it. Remove anything that could break (like the the lever(s)) or that could stab you on accident (like a drill bit).
Wearing gloves is not recommended when using the drill press (or any spinning power tool, for that matter). However, for taking one apart, good work gloves may protect your hands from getting dirty and/or cut up.
Step 3: Remove Pulleys and Power Switch
Take the pulleys and the v-belt completely off using a hex wrench to loosen the setscrews. If the pulleys are different sizes, you might want to mark which one goes where. Mine were different sizes, but the holes were different diameters, so I didn't have to worry about mixing them up.
Remove the power switch by unscrewing it and undoing the wires. Again, mark which wires go where so you don't mix them up later. My drill press had two wires attached to the switch, and two more screwed to the cast iron drill press head.
Step 4: Remove Drill Press Head
Take off the head by loosening the two set screws and then lifting the head off the column. Be careful when setting it down that you don't break the depth stop.
Step 5: Take Off the Pulley Housing
Now that the pulleys are off and the wires are not attached to the head, you can unscrew the pulley housing. Make sure the wires won't get stuck before pulling the entire thing off. You do not have to remove the wires from the inside of the pulley housing, so long as you do not mind that the motor and the pulley housing are still connected.
Step 6: Take Out the Pin
Swing the motor out from its usual position. Hidden by the motor is a roll pin which stops the column from going all the way through the drill head. Tap the pin out with a pin punch and a hammer.
Step 7: Mark and Partially Reassemble
Use the marker/paint/layout fluid to put a big blob on the underside of the pulley housing approximately where the column will hit it now that the roll pin is out of the way.
Partially reassemble the press head (if you used spray paint, wait until it dries). Just screw the pulley housing back on where it was. Then put the head on the column until the end of the column contacts the underside of the pulley housing. Spin the head around a few times. Take the head off and remove the pulley housing again. If you did it right, there should be a circular mark on the ink/paint blob you put on that indicates where the column hits the housing.
Step 8: Make the Hole
Make the hole through the bottom of the pulley housing. Make sure to avoid drilling through wires. If you've got a hole saw the right size, great. It should take you a few seconds to drill through.
If you do not have a hole saw, I would recommend drilling around the inside of the circumference of the circle with a smaller bit (like 3/16" or so), prying out the inside, then smoothing down the edges with a Dremel grinding bit or a file. Check to make sure that the column will fit through the hole.
If you want, you can also put the hole through the top of the pulley housing so you can keep the lid shut while the drill is on. However, you will probably want to make a cover for it so dust doesn't get in.
Regardless of how you make the hole, make sure to clean the inside of the housing before proceeding.
Step 9: Reassemble and Profit
Reassemble the drill press head, first. Screw the pulley housing back on, attach the pulleys and the belt, and reconnect the power switch. Then open the housing and slide the head back on the column. Move the table to the side, and turn the chuck 180 degrees from where it usually is in relation to the base. Adjust the height of the head by putting a drill bit in the chuck and gently lowering the head until the bit just barely touches the floor. Tighten the set screws on the head to lock it in place.
Congratulations! You can now use your drill press on practically any surface. It's more durable, accurate, and controllable than one of those hand drill guide attachment things. It's also cheaper than buying a $1000+ magnetic drill press.