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Releasing seized screws by impact

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What is the issue?
Screws, like most every fastening, have a tendency to seize up on a sea going vessels. Engine casing bolts can also be set in place very tight making them difficult to loosen and unscrew.

Why address this?
A seized screw can cause major delay and on occasion damage if it has to be dug out. This could present a very challenging situation on an engine casing.

How to address this?
If you have a large, old and solid screwdriver, sit it into the slot and strike it with a hammer. The impact may jolt the screw in its seat breaking the locking tension.

However a better solution is to use a specialist tool called an impact driver (occasionally known as an impact wrench) also presented in figure 1.

This screwdriver sized tool comes with a socket stub where you fit the appropriate socket head for the challenging bolt in question. Once the bit is in the stub you place it upon the screw. Then you strike the impact driver with a hammer or mallet whilst also applying a slight opening force on the body of the impact wrench.

The hammer strike is translated into a sudden twisting motion at the head of the bolt. Static friction decreases when force is applied in a short burst. The jolt of an impact driver will shift highly resistant bolts. It can move bolts that would have required that much force that they may have snapped off before releasing under normal conditions.

This is an excellent tool to add to the vessels maintenance arsenal. It takes a little practice to keep the bit directly upon the bolt when you hammer it but all you need should be one or two clean strikes to get the job done.

Be careful not to confuse the hand held tool with pneumatic impact drivers that are larger to stow, more expensive, require mains power and are thus not warranted upon a boat for the limited occasional usage they will find.

With thanks to:
Michael Harpur, Yacht Obsession.

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