How to Use a Tap & Die
Properly functioning screws and bolts are integral to nearly any household project. When they lose their teeth -- when they are stripped -- they will bind and otherwise not work. Sometimes, replacing a screw or bolt is not practical for financial or time reasons. When this is the case, a tap and die set is a key workshop item for getting the project back on track. The tap part of the set works with nuts, while the die is used to repair bolts.
Calculate the number of threads per inch in the screw or bolt with which you're working. Tap and die sets include a gauge that calculates threads per inch.
Select the corresponding die that matches with the reading on the thread per inch gauge, and set the die in the handle that comes with the set.
Secure the head of the damaged bolt or screw in a vice, and turn the die onto its damaged thread, adding lubricant periodically.
Blow the area with compressed air every few turns of the die to ensure the metal shavings don't clog the area.
Continue turning the die until you have moved along the screw or bolt's entire length smoothly.
Use the gauge to determine the thread count of the damaged nut. If you've already used a die on a corresponding bolt, the thread count will be the same.
Select the corresponding tap that matches with the reading on the gauge, and set it in the handle.
Place the nut in a vice, and begin turning the tap into it. Use oil periodically, and blow any metal shavings away with compressed air.
Thread the repaired nut onto the repaired bolt. They should fit correctly. If not, try the tap and die process again.