How to Tap on a Drill Press
Tapping a hole puts threads on the inside to receive a screw. For precision's sake, a drill press is recommended for both boring the initial hole and tapping it. Attachments are necessary to make it possible to tap on a drill press, as most machines are not set up for such. Proper hole width and concentricity have to be established and it takes a learned touch to accurately tap a hole. Even seasoned craftsmen break a tap occasionally, and ruin a project in the process. Does this Spark an idea?
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Instructions
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Drill the initial hole on a drill press for accuracy of diameter. If the diameter is 1/2 inch or larger, drill a pilot hole about half that diameter first.
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Prepare the drill press for tapping. Add a tapping attachment to upright and sensitive drill presses. This sleeve is the solution for two tapping needs. It automatically reverses rotation whenever the drill is raised, so the tapped threads are preserved. Torque can also be set to stop rotation and prevent the binding that breaks taps.
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Use a center finder. Place a pointed center finder on the chuck to line up the center of the spindle with the hole.
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Select the tap type. Choose from a taper tap, plug tap or bottoming tap. The taper tap has several chamfer threads forming a tapered cone on the inserting end. The plug tap has fewer chamfer threads and a bottoming tap only has a couple chamfer threads.
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Match the tap size. Use the specified tap size to thread the hole diameter. Taps that are sold with drill bits are size matched for you. The taps themselves may show the hole size they’re intended for, but it’s likely to be given in metric notation. Use a conversion chart to match this with the inch fractions measuring drill bits.
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Cut the threads. Lubricate the tap with tapping fluid. Start the drill press and lower the tap gently into the hole to be threaded. It only takes a few seconds to tap a hole. As long as it has been set up properly, the chances are good for success.
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Tips & Warnings
Tapping is a skill. It takes practice to do it well and to not break taps. If you’re new to tapping, practice on sample stock before tapping into your actual project.
Materials have differing requirements for drill speed and lubrication. Hole depths and diameters may present additional drilling requirements. Refer to material charts for drilling specifications.
