[experience sharing] 26 methods teach you to take out the tap broken in the hole!

People engaged in machining know that taps are always broken several times when tapping threads, especially during CNC machining. Some are still deep holes, which is a headache. Therefore, today we have sorted out 26 methods to take out broken taps!

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1. Fill some lubricating oil, use a sharp hairpin or chopper to knock it out slowly in the opposite direction on the fracture surface, and pour the iron from time to time (the most commonly used method in the workshop, but it may not be appropriate for the threaded hole with too small hole diameter or the broken tap is too long, but you can try);

2. Weld a handle or hexagon nut on the broken section of the tap, double Sided Tape and then turn it back slightly (it is a good method, but the welding is troublesome. In the same case, it is not suitable for the tap with smaller diameter);

3. Use special tool: broken tap extractor. The principle is that the workpiece and tap are connected with positive and negative electrodes respectively, and electrolyte is filled in the middle, resulting in the discharge corrosion of the workpiece to the tap, and then take it out with pointed nose pliers, which will cause little damage to the inner hole

4. Take the steel roller to top the tap crack and knock it slowly with a small hammer. The tap is relatively brittle, and finally it becomes slag. Or more simply, directly drill the threaded hole of the broken tap, bore it alive, ream and tap again (the method is a little barbaric. If the tap diameter is too small, it is difficult to use, and the diameter is too large, it is also very tiring to knock);

5. Weld, grind and re drill the threaded hole where the broken tap is located. Although it is difficult, it can be drilled slowly (if the threaded hole can be changed, it is recommended to replace it next to the original threaded hole when re drilling and tapping);

6. Chisel a slotted groove on the section of the broken tap and screw it up reversely with a screwdriver (the slotted groove is difficult to chisel out, especially if the tap diameter is small);

7. Drill the thread hole of the broken tap, and then insert a steel wire screw sleeve or pin, double Sided Tape then weld, grind, re drill and tap, which can be basically the same (although this method is troublesome, it is very practical, and the tap size doesn't matter);

8. It can be knocked off by electric pulse, electric spark or wire cutting. If the hole is damaged, the hole can be enlarged and steel wire screw sleeve can be added (this method is simpler and convenient. As for the coaxiality, do not consider it for the time being, unless the coaxiality of your threaded hole directly affects the quality of the equipment);

9. Make a simple tool and insert it into the chip removal slot of the broken tap section at the same time, and pull it out in the opposite direction carefully. For example, screw 2 nuts on the broken tap with square tenon, insert steel wire (the number is the same as the number of tap slots) into the empty slot of the broken tap and nut, and then pull the square tenon with hinge screw according to the withdrawal direction to take out the broken tap (the theme of this method is to connect the chip removal slot of the broken tap, and use the steel wire, preferably the steel needle, to make a wrench for taking the broken wire. Of course, if such broken wire often occurs in the workshop, it is better to make such a tool wrench);

10. Nitric acid solution can corrode the high-speed steel wire cone without scrapping the workpiece.

11. Anneal the tap with acetylene flame or blowtorch, and then drill with a drill bit. At this time, the diameter of the drill bit shall be smaller than the diameter of the bottom hole. The drilling shall also be aligned with the center to prevent the thread from being damaged. After the hole is drilled, drive a flat or square punch, and then screw out the tap with a wrench

12. It depends on the feel of the hand to reverse with an air drill, double Sided Tape because instead of directly drilling out the tap, it uses slow speed and a little friction (similar to automobile semi clutch) to make the tap turn out.

14. You can use a grinder to smooth the broken wire, then drill with a small drill bit, and then gradually use a larger drill bit. The broken wire will gradually fall off, and then tap the tooth again with a tap of the original size. This advantage does not need to increase the hole diameter.

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15. Weld an iron bar on the broken object and screw it out. (disadvantages: A. too small broken object cannot be welded; B. high requirements for welding skills and easy to burn the workpiece; C. the welded joint is easy to break and the probability of taking out the broken object is very small.)

16. Pry with a cone-shaped tool harder than the broken object. (disadvantages: A. It is only suitable for brittle broken objects, break the broken objects, and then slowly remove them; B. the broken objects are too deep and too small to be taken out; C. It is easy to destroy the original holes.)

17. Make a hexagonal electrode smaller than the diameter of the broken object, machine a hexagonal counterbore on the broken object with an electric spark machine tool, and then screw it out with an Allen wrench. (disadvantages: A. It is useless for rusted or stuck broken objects; B. It is useless for large workpieces; C. It is useless for too small broken objects; D. It is time-consuming and laborious.)

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18. Directly use the electrode smaller than the broken object and hit it with the electric spark machine tool. (disadvantages: A. It is useless for large workpieces and cannot be put into the workbench of the electric spark machine tool; B. It is time-consuming; C. It is easy to deposit carbon when it is too deep and cannot be hit.)

19. Use alloy bit to drill (disadvantages: A. It is easy to destroy the original hole; B. It is useless for hard broken objects; C. alloy bit is brittle and easy to break.)

20. Now there is a portable tool machine designed and manufactured based on the principle of electric machining, which can easily and quickly take out the broken screw, broken tap and drill bit.

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21. If the screw is not too hard, you can flatten the end face, find the center point, punch a small point with a sample punch, drill with a smaller bit first, be vertical, and then screw it out reversely with a broken wire extractor.

22. If you can't buy a broken wire extractor, use a larger drill to continue reaming. When the hole diameter is close to the screw, some wires will fall off. Remove the remaining wire teeth, and then use a tap to repair them.

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23. If the broken screw is exposed, or the requirements for the broken screw are not strict, and it can be sawn with a hand saw, you can sew with a saw blade, even the shell, and then remove it with a flat screwdriver.

24. If the broken wire is exposed for a certain length and the melting point of mechanical materials is not too low, double Sided Tape an extended T-shaped rod can be welded on the screw by electric welding, so that it can be easily screwed out from the welded rod.

25. If the screw is seriously rusted and it is difficult to deal with it by the above methods, it is recommended to bake it red by fire, add a little lubricating oil, and then deal with it by the above corresponding methods.

26. After more than n efforts, although the screw is taken out, the hole is also abandoned at this time. Simply drill a larger hole for tapping. If the original screw position and size are limited, you can also drill a larger screw in, or directly weld the tapping, and then drill a small hole for tapping in the center of the large screw. However, it is sometimes difficult to tap the internal metal structure after welding.