Just about everyone who has worked in a mechanical or hardware field has experienced the pain of trying to get a screw into a stripped-out hole. Often, putting a screw in wrong or repeatedly taking it in and out of a hole will cause the threads to wear down and eventually be unable to hold the screw anymore. Fortunately, a tap and die set offers a solution to this problem.
- Skill level:
Things you need
- Vice (attached to work table or otherwise secured)
- Oil. Special tap and die oil is available, but motor oil works too
- Kerosene, for cutting aluminium
Understand what a tap and die does. A tap is a long, tapered piece of metal that is placed in a hole and twisted to cut new threads all the way down the hole. A die is a metal doughnut with handles that you place over a screw and twist it so it cuts new threads into the screw. In a tap and die set, you will have several taps and dies of different sizes. Sizes can be standard or metric, and which one you use will depend on the object you are working on.
Choose the correct tap for the job you want to do. Most projects done by hand will use a "taper" tap, which tapers gradually and creates threads as it is twisted. You also have "bottom" taps (used to lengthen an existing thread in a hole) and "plug" taps (used in production lines). Determine what size tap you need, either by eyeballing the hole you are working on or by using a chart.
Choose the correct die. When using a tap and die set, there are corresponding sets of taps and dies in the kit. You should use a tap to recut the threads of a hole when you need to use a die, and vice versa. This is because, for example, if you only cut threads on the screw with your die and then try to stick the screw in the hole with the old threads, it probably won't fit well.
Secure the object you are working on in a vice and tighten it (see Resources). If the object slips while you are cutting new threads, it will mess up the threads, and you will have to secure the object and start over.
Dip your tap or your screw in oil. If you are cutting aluminium, kerosene works better than oil to lubricate the tap and die. The purpose of lubrication is to cut down on friction and reduce the chances of breaking your tap or screw.
Work the tap and/or die by twisting slowly. Turn it clockwise until you feel resistance, then turn it counterclockwise to free it up a little. Turn it clockwise once more until you feel resistance again, and turn it counterclockwise to free it up. You'll probably feel resistance every twist or two, so go slowly and be patient.
Tips and warnings
- Do not force the tap or die, or you will break the tap or the screw. Simply twist it back and forth, clockwise then counterclockwise, and it will free up and allow you to continue twisting.
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