Home generalDrill off broken / solid screw: Instructions for left-hand rotors

Drill off broken / solid screw: Instructions for left-hand rotors

  • Left-hander in detail
  • Tool and preparation
  • Bore out the screw: Instructions

The desperation is great when a screw breaks or sits so tight that the screw head is leaking and not moving a millimeter. In such cases, it is necessary to find another way to loosen the screw. Boring out the screw is often the only way to solve this problem and replace it with a new one.

With their properties, screws are among the most important fastening materials that humans invented and are available in numerous versions and types. Despite their usefulness, they wear out over time, may break or suffer from a screw head that has been ground down so far that it no longer grips properly with the screwdriver. If you do not want to grind the entire screw with the angle grinder or damage the workpiece, you will need to drill out the screw. For this you have so-called left-hand extractors, which were developed especially for this purpose. They allow loosening of the screw, even if they are broken off or worn out.

Left-hander in detail

The Linkausdreher is a tool that has a continuous left twist. They resemble a drill in shape, but are not used with a drill, but with an angle iron. The "pig tail", another name of the extractor, comes in different sizes, but is always applied in the same way. Thanks to its conical shape, it can easily penetrate into the screw, grab it from the inside and release it from the workpiece. They are usually offered in sets and are priced from 5 to 30 euros, depending on the quality. Of course, only right-handed screws can be solved with left-hand rotors.

screw extractor

Tip: in addition to the classic variant, which is used together with an angle iron, there are variants that can be used with the drill or the cordless screwdriver. These are equipped on one side with a drill and on the other with a left-hander, which is to facilitate the use.

Tool and preparation

If you want to drill a screw with a left-hand tool, you need the following tools:

  • screw extractor
  • Tap wrenches of appropriate size
  • grains
  • hammer
  • Twist drill bits in appropriate size
  • drilling machine
  • metal file
Tap wrench and vise

The size of the bits and the winder gear are based on the size of the left-hand extractors and should be coordinated with each other when purchasing. If you already have a bit set, there is a good chance that you already have the right drill and you only have to compare it with the left hand tool. With the tap wrench, in most cases, an adjustable version of M4 to M12 is sufficient. If you need to drill larger screws, use an M16 to M20 tap wrench. The sizes of the individual left hand extractors with the corresponding tap wrench are typically structured as follows:

  • Size 1: M4 with 1.8 mm diameter for the twist drill
  • Size 2: M5 - M7 with 3.2 mm diameter for the twist drill
  • Size 3: M8 - M11 with 4.5 mm diameter for the twist drill
  • Size 4: M12 with 6.5 mm diameter for the twist drill
  • Size 5: M16 - M20 with 8.5 mm diameter for the twist drill
  • Size 6: M20 with 12 mm diameter for the twist drill

In the end, you will know exactly which tap wrench and which twist drill you need to be able to drill out the screw. The values ‚Äč‚Äčlisted above are the most common home left-turn values.

After you have procured the necessary materials and tools, now comes the preparation of the screw. Please note that this step is only necessary with broken screws, which have sharp edges and pose a risk of injury. If the screw is tight or worn out, you do not need to make any further preparations. Take the file and work on the breakage of the screw until it is level and no longer sharp. This may take a while, depending on the size of the screw, but this step makes drilling much easier. The preparation is omitted as soon as the screw breaks off in the thread and can no longer be achieved in conventional ways.

Bore out the screw: Instructions

You have prepared the screw and can now proceed with the drilling. For boring, you should definitely take your time, so that all work steps are carried out precisely, because in the worst case, you can make the initial condition even worse. The instructions as follows:

Step 1: Firmly clamp the workpiece in which the screw is located. If it is an object that stands alone and can not be moved, such as a piece of furniture, this is not necessary.

2nd step: Now measure the diameter of the screw. If you do not have a spare screw, you can measure the broken part or unscrew and measure one of the other identical screws. Based on the diameter of the screw you first determine the thread type that matches the tap wrench and then you need the above diameter for the hole.

Step 3: Next, pick up the grains and place them exactly in the middle of the screw head or the broken screw. You must make sure that the grains are exactly in the middle, otherwise there will be problems during drilling. Slightly hammer the kernel into the screw and make a small hole. This serves as a marker, which makes it easier to apply the drill afterwards.

Step 4: Now take the appropriate twist drill and insert it into the drill. Now drill from above into the screw and orient yourself thereby at the grain. Make sure to drill exactly in the center, as a skewed drill bit would widen the screw like a dowel, thereby reinforcing the seat. Drill about half the length of the drill bit in the screw.

Step 5: After you have completed the drilling, remove the drill residue and insert the appropriate left hand extractor in the tap wrench. Now you can drill out the screw.

Step 6: Place the left hand tool as far as it will go into the hole, optimize the placement and start turning to the left. Proceed as accurately as possible so that the left-hander does not shift. Each time the winch is turned, the screw is slowly unscrewed. Dose your power so as not to put too much pressure on the material.

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