Tips and advice: screw identification and removal

There are many types of screw and fasteners used in modern electrical products - some of these are designed to prevent unauthorised access to electrical components.

Listed here are some of the types of screw or bolt heads that you may come across when repairing items in the home.

For information on how to tackle and resolve faults and problems on a wide range of appliances see our other articles »

Many of these screw driver heads are available with a magnetic bit screwdriver kit, but the illustration may help to identify and order special screwdrivers to dismantle most appliances and devices.

Even with the right type of tool it is important to use the right size of blade or tip to prevent slipping or damage to the screw head.

On some occasions it may not be possible to remove the screw without damaging or 'chewing' the head of the screw, so below are a few engineer's tips on how to remove corroded or damaged screws. Bear in mind that stubborn screws will be less of an issue to remove with a higher quality and properly fitting screwdriver.

Where possible, apply releasing or penetrating oil like WD40 and allow it to soak for several minutes before trying to remove a stubborn screw.

If the screw is corroded or damaged, find a screwdriver or bit that fits the head of the screw as close as possible. Fit the driver into the screw head and sharply tap the handle with a hammer to punch the bit into the screw head and through any corrosion or minor damage.

Then, if the screw driver seems to be gripping the screw, try to tighten it slightly; this may allow the screw to release itself from the thread so that a high turning pressure can be applied without risk of chewing off the edges. If some rotation is felt (and possibly even a small click) then try undoing the screw.

However, if this technique has been ineffective, position a flat blade screwdriver at an angle on the rim of the screw head. Using the screwdriver as a chisel, tap the handle firmly to push the screw head round anticlockwise, thus breaking the screw thread's grip on the surrounding material.

If the screw is starting to rotate but the head is drilled out by a slipping or worn bit, try placing a rubber band between the driver tip and screw. This will provide more friction between the screwdriver and screw head, allowing additional turning torque to be transferred to the badly worn screw.

If you can access the head of a badly damaged screw you can try pinching side cutter pliers into the head's edges, then rotating while continuing to apply pressure.

Alternatively, carefully cut a new slot across the head of a worn screw slot and remove the screw with a larger flat blade screwdriver.

If it has been necessary to drill the screw head off, or if the head shears off a screw, try turning the exposed screw shaft (if accessible) with a pair of pliers or grips to remove it.

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* All information provided is a guide only. BuySpares accepts no liability for any problems occurred while attempting any advice shown. If in any doubt contact a qualified repair service.