When the factory is processing CNC machining parts, CNC turning parts and CNC milling parts, it often encounters the embarrassing problem that the taps and drills are broken in the holes. The following 25 solutions are compiled for reference only.
1. Fill some lubricating oil, use a pointed hairpin or a chopstick to slowly knock out the fracture surface in the opposite direction, and cut it upside down from time to time (the most commonly used method in the workshop, but it is too small for threaded holes with too small diameter or broken taps. The length may not be appropriate, but you can try).
2. Weld a handle or a hexagon nut on the broken section of the tap, and then gently reverse it out (it is a good method, but welding is a bit troublesome, or the same, it is not suitable for taps with smaller diameters);
3. Use a special tool: a broken tap extractor, the principle is that the workpiece and the tap are connected to the positive and negative electrodes respectively, and the electrolyte is filled in the middle.
Cause the workpiece to discharge and corrode the tap, and then assist needle-nose pliers to take it out, with little damage to the inner hole;
4. Take the top of the steel roller and tap it slowly with a small hammer on the crack of the tap. The tap is relatively brittle, and it will eventually be knocked into slag. It’s a bit barbaric, if the diameter of the tap is too small, it won’t work well, and if the diameter of the tap is too large, it will be tiring to tap);
5. Weld the threaded hole where the broken tap is located, then grind it flat, and re-drill the hole. Although it is difficult, you can drill in slowly (if the threaded hole can be changed, it is recommended to change it when re-drilling and tapping) to the side of the original threaded hole);
6. Chisel a slot on the section of the broken tap, and screw it up in reverse with a screwdriver (the slot is difficult to chisel out, and it will be even more difficult if the diameter of the tap is small);
7. Drill the threaded hole of the broken tap, and then insert a wire screw sleeve or pin or something, then weld, grind, and re-drill and tap the hole, which can be basically the same (this method is troublesome, but it is very practical) , the size of the tap does not matter);
8. Use electric pulse to destroy, EDM or wire cutting can be used, and if the hole is damaged, you can ream the hole and add a wire thread sleeve (this method is more simple and convenient, as for the coaxiality, don’t consider it for the time being, unless your threaded hole is the same The axis directly affects the quality of the equipment);
9. Make a simple tool and insert it into the vacancy of the chip removal groove of the broken tap section at the same time, and pull it out carefully in reverse. ) Insert the broken tap and the empty groove of the nut, and then use the hinge bar to pull the square tenon in the direction of withdrawal, and take out the broken tap (the main idea of this method is to clear the chip groove of the broken tap, use steel wire, preferably Use the steel needle to make a wrench for broken wires. Of course, if such broken wires often occur in the workshop, it is better to make such a tool wrench);
10. The nitric acid solution can corrode the high-speed steel tap without scrapping the workpiece;
11. Anneal the tap with an acetylene flame or a blowtorch, and then use a drill to drill. At this time, the diameter of the drill should be smaller than the diameter of the bottom hole, and the drill hole should also be aligned with the center to prevent the thread from being damaged. After the hole is drilled, punch a flat Or a square punch and then use a wrench to unscrew the tap;
12. Use the air drill to take it in reverse, it all depends on the feel, because the tap is not drilled directly, but the tap is rotated out with a slow speed and a little friction (similar to a car half-clutch);
13. You can use a grinder to smooth the part of the broken wire, then use a small drill bit to drill first, and then gradually change to a larger drill bit. The broken wire will gradually fall off. After falling off, use a tap of the original size to tap the tooth again. The advantage is that there is no need to increase the aperture;
14. Weld an iron rod on the break-in and screw it out. (Disadvantages: Too small broken objects cannot be welded; the requirements for welding skills are extremely high, and the workpiece is easy to be burned; the welding place is easy to break, and the probability of taking out the broken objects is very small)
15. Pry with a tapered tool harder than the entry. (Disadvantages: only suitable for brittle broken objects, crush the broken objects, and then slowly pick them out; the broken objects are too deep or too small to be taken out; it is easy to damage the original hole)
16. Make a hexagonal electrode smaller than the diameter of the broken object, machine a hexagonal counterbore on the broken object with an EDM, and then screw it out with an Allen wrench. (Disadvantages: Useless for rusted or stuck broken objects; useless for large workpieces; useless for too small broken objects; time-consuming and troublesome)
17. Directly use an electrode smaller than the broken object, and use an electric discharge machine to strike. (Disadvantages: it is useless for large workpieces, and cannot be put into the workbench of EDM machine tools; time-consuming; when it is too deep, it is easy to deposit carbon and cannot be punched)
18. Drilling with an alloy drill bit (disadvantages: easy to damage the original hole; useless for hard broken objects; alloy drill bits are brittle and easy to break)
19. Now there is a portable machine tool designed and manufactured using the principle of electric machining, which can easily and quickly take out broken screws and broken taps.
20. If the screw is not too hard, you can flatten the end face, then find the center point, punch a small point with a sample, drill with a smaller drill bit first, make it vertical, and then use a broken wire extractor to screw it in reverse Just go out.
21. If you can’t buy a broken wire extractor, use a larger drill bit to continue reaming. When the hole diameter is close to the screw, some wires will fall off uncontrollably. Remove the remaining wire teeth, and then use a tap to re-trimming.
22. If the broken wire of the screw is exposed, or the requirements for the broken screw are not strict, you can still saw it with a hand saw, you can saw the seam of the blade, and even the shell, and then remove it with a flat screwdriver.
23. If the broken wire is exposed to a certain length, and the melting point of the mechanical material is not too low, you can use electric welding to weld an extended T-shaped bar on the screw, so that it can be easily unscrewed from the welded bar.
24. If the screw is very rusted and it is difficult to deal with the above method, it is recommended to add a little lubricating oil after roasting it with fire, and then use the above corresponding method to deal with it.
25. After much effort, although the screw was taken out, the hole was useless at this time, so we simply drilled a larger hole for tapping. If the original screw position and size are limited, we can also drill a larger one. The screw goes in, or the tap is welded directly, and then a small hole is drilled in the center of the large screw for tapping. However, it is sometimes difficult to tap the internal metal structure after welding.
Post time: Jan-28-2023