ADMINISTRATION
EXPLAIN: Able to explain how to correctly use a hand tap to thread an internal/external hole according to manual.
PROCEDURE
The employee will explain as follows
1) How to use hand tap?
2) How to select the drill bit?
3) How to select taps?
4) How to use the die for external threading?
5) How to select die head to thread with hand die?
Answer:
A tap cuts threads on the inside of a hole, to accept a machine screw or bolt. Taps can also be used to restore an internal thread that has been damaged or to cut a new, larger thread in the case of severe damage or stripping.
1. Determine the size and depth of the thread that you want. What size screw will go into this hole?
2. Refer to a technical publication for the exact measurements for hole size. For example, if you want to use a 1/4-20 screw then you must use a #7 drill bit. Your set of taps may also state the appropriate hole size to use with each tap
3. Drill the hole to the correct diameter and depth. Remember that taps generally cannot thread all the way to the bottom of a blind hole, so a blind hole must be a bit deeper than the required thread depth
4. Secure the workpiece firmly.
5. Apply an appropriate lubricant such as oil, WD-40, or a proprietary formula.
6. If the tap set has a separate handle or rod, insert it.
7. Hold the tap in line with the hole and turn it clockwise. Try to keep it very straight as you turn. You may feel the material breaking.
8. Every few turns, back the tap out (counterclockwise/anticlockwise) to clear away chips of loose material. This is especially important in a blind hole, one that does not go all the way through the workpiece.
9. When the tap has reached the required depth, back it out, clean out chips and any cutting fluid or lubricant, and try your screw or bolt in it.
1. Chamfer end of work piece with file or on grinder
2. Fasten work securely in vise
3. Select proper die and die stock
4. Lubricate tapered end of die with suitable cutting lubricant
5. Place tapered end of die squarely on work piece
6. Press down on die stock handles and turn clockwise several turns
7. Check die to see that it has started squarely with work
8. If not square, remove die and restart
9. Turn die forward one turn and reverse it approximately one-half turn to break chip
10. During threading process, apply cutting fluid frequently
If thread must be cut to shoulder, remove die and restart it with tapered side of die facing up (complete the thread)