The tap or drill bit breaks in the hole, how to fix it?

The breakage of tools and cutters is a key factor affecting the qualified rate of products. The conventional methods to deal with taps and drills that are broken in the workpiece are nothing more than slowly knocking them out manually, smashing them, twisting them out after gas welding, or using acid corrosion, flame cutting and burning, but the effect is not very good. Today, the editor will share several tips for dealing with breakage.

Dripping lubricant and hitting

Pour some lubricating oil, use a pointed hairpin or a chopper to slowly knock out the fracture surface in the opposite direction, and occasionally reverse the iron chip (this is the most commonly used method in the workshop, but it may not be suitable for threaded holes with too small apertures or broken taps that are too long, but you can try it).

Welding hexagon nut reverse

Weld a handle or hexagonal nut on the broken section of the tap, and then gently reverse it out (this is a good method, but welding is a bit troublesome and not suitable for taps with smaller diameters)

Tap extractor

Use a special tool: a broken tap extractor. The principle is that the workpiece and the tap are connected to positive and negative electrodes respectively, and electrolyte is poured in the middle, causing the workpiece to discharge and corrode the tap, and then it is removed with auxiliary needle-nosed pliers, etc., with little damage to the inner hole.

Steel rods hold the cracks

Put a steel roller against the crack of the tap and tap it slowly with a small hammer. The tap is relatively brittle and will eventually be knocked into slag. Or it is even simpler to drill or bore the threaded hole of the broken tap and then re-expand and tap (this method is a bit barbaric. If the tap diameter is too small, it will not work. If the tap diameter is too large, it will be very tiring to tap it).

Electric pulse knock out

Use electric pulse, electric spark or wire cutting to knock it off. If the hole is damaged, you can expand the hole and add wire thread sleeve (this method is simpler and more convenient. As for coaxiality, don't consider it for the time being, unless the coaxiality of your threaded hole directly affects the quality of the equipment).

Reverse pull out

Make a simple tool and insert it into the empty space of the chip groove of the broken tap cross section, then carefully push it out in the opposite direction. You can screw two nuts on the broken tap with square tenon, insert steel wire (the number of wires is the same as the number of tap grooves) into the empty grooves of the broken tap and nut, then use a hinge lever to push the square tenon in the exit direction to take out the broken tap.

Conical tool pry

Use a cone-shaped tool that is harder than the broken object to pry. (Disadvantages: only suitable for brittle broken objects, break the broken objects and then pick them out slowly; broken objects that are too deep or too small cannot be taken out; easy to damage the original hole).

If it is a special screw, and you accidentally use too much force and break the screw head, then there is another way.

First use a positioning pin to make a positioning hole.

The tap used is required to be left-handed. (Note: the right-handed tap is turned toward the inside of the bolt. If the direction is wrong, the bolt will be broken.)

After drilling, the screw will be exposed a little outside the bolt. At this time, it is necessary to gently screw it out with a left-handed tap.

The last step is to successfully unscrew the entire bolt, that is, the remaining screw part, while ensuring that the external thread of the bolt is intact.