How Does the Extractor for Damaged Screws That Won't Unscrew Work?

One of the typical problems for those who deal with mechanics and repairs: finding yourself facing a screw that refuses to come out. Often the cause is rust, oxidation blocks the thread. And if you don't use the right tools, you risk damaging the head and having to manage a stuck bolt or one that spins uselessly. And that's where the extractor for stripped screws comes in. That is, a sort of tip with a special inverted blade that allows you to remove screws that no longer have the right section to accommodate a screwdriver.

This also applies to hex socket screws, these solutions too can become stripped: it happens when the section that holds the tool is damaged and deformed to the point that it no longer offers resistance. What do you do? Professional mechanics use the appropriate tools.

What Is a Stripped Screw Extractor?

It is a mechanical tool that allows you to unscrew a screw or bolt when the necessary grooves to engage the standard tool are damaged. And you can no longer screw or unscrew with a normal screwdriver. Or with a hex key.

There are different models of extractors, the most common (and the one you also find in the Krino catalog) is the reverse spiral extractor. These tools have reverse threading that screws into the damaged screw by turning counterclockwise.

This mechanism allows the operator to extract the element that cannot be handled otherwise. If, instead, the screw is blocked by a rusty nut, you can use a vise extractor that clamps around the nut head to break it.

How Is This Tool Made?

You recognize it right away because of its shape. The body is made of tempered steel with high strength, often completed and refined with surface treatment to prevent corrosion. It is a tool that needs a solid base because its purpose is to score the metal of the screw: this phase occurs with the main tip that is known as the penetration tip.

It is a slightly conical end that is designed to penetrate easily into the metal of the damaged screw. The characteristic of this solution: the thread rotates in the opposite direction to the normal. So it's counterclockwise. And it has an aggressive pitch with profiles that score the metal. In this way, the tool grips and allows the person unscrewing to perform the operation. As you can see from the image above, the opposite end is dedicated to engagement in the drill chuck or driver.

To read: how to extract a broken stud

How Do You Use the Stripped Screw Extractor?

The operation involves a series of steps. Clean the area and try to lubricate, if possible, the thread to simplify the operations. But without soiling the screw head. Then, choose a screw or stud extractor of the appropriate size.

Usually, those who often work with these tools have kits with different sizes because the tool must be large enough to have a grip on the bolt, but not so large as to break or further damage it. With a drill bit for metal, smaller than the extractor, drill the center of the stripped screw. Do this slowly and precisely, without too much depth.

Usually 3 or 5 millimeters is enough for larger screws: some extractor models also have the dual function. In fact, on one side there is the tip for pilot hole and on the other the reverse thread. Once you've completed this operation, you need to position the extractor section so it's perpendicular to the surface. Turn the tool slowly counterclockwise, applying slight downward pressure. The reverse thread will begin to score the screw metal, gripping securely.

Continuing to proceed counterclockwise, when the extractor reaches its end, it will begin to unscrew the element naturally, without effort. If the screw is stuck by rust, before using the extractor, try to heat the area slightly with a heat gun or let a penetrating rust remover work. Sometimes it's essential to unlock the situation.