FIXING THE FIXTURES

Damaged screws can be a pain to remove, Pete Evans explores some solutions

- Pete Evans

Anyone who has been involved in working on airguns will have encountered screws that are stuck, damaged, or in some cases sheared off completely. This can be a frustrating and sometimes costly occurrence, but ultimately not an irrevocable situation.

This study seeks to provide practical guidance for these workshop challenges. Some might be old hat, others more novel in their approach, but all have one thing in common, on one occasion or another they have all come to my aid.

THE HEAT IS ON

Physics is a marvellous thing, the correct application of which will work to our advantage, so let’s consider the concept of thermal expansion. When heat is applied to metal, it expands and the rate of expansion depends upon the composition of the metal. As an example, aluminium expands roughly twice as much as mild steel for the same temperature of applied heat. This physical law is definitely one that we can exploit to our advantage in the context of a stuck fastener.

Heat applied to the object into which the fastener is stuck can expand the internal thread minutely, which will help to release the fastener. This method can work well in conjunction with penetrating oil; heating the area to expand, then applying the oil to penetrate and ease the passage of the screw. It is important to heat the surrounding area rather than the fastener itself because it’s not the fastener that we wish to expand.