Fasteners that are too tight to undo can frustrate even the most seasoned builder or engineer but, before you throw your spanner against the wall in despair, try some of these tips to loosen that stubborn bolt.
Take a step back and try and work out what the problem is. Is the fastener corroded? Are the workpieces out of line with each other? Or is it just that the fastener was done up too tightly?
If the workpieces are out of line, try wiggling them around to line them up. Ideally, they need to be in the same position relative to each other as when the bolt was fitted. Often, the angle of the workpieces has changed, locking the bolt in place.
Try using a stronger spanner. Ratcheted spanners are often weaker than their non-ratcheted counterparts and spanners with thicker jaws are stronger too. A spanner with a 6-point profile or open-ended spanners are the best because they have better grip on the fastener than 12-point profiles.
Rock the spanner back and forth, trying to turn it clockwise then anticlockwise. This can loosen the components and be enough to undo the fastener.
If the fastener is mildly corroded you might find that a drop of penetrative oil left to soak in will loosen the corrosion and allow you to undo the fastener.
If it still won’t budge, try using a breaker bar. Breaker bars are long shafts with a socket end which provide more leverage and force on the fastener than a spanner. If, when you are turning the breaker bar, the fastener starts to feel a bit bouncy and ‘soft’ then it is likely the fastener is about to break. Rocking the spanner (as above) is the best way to prevent the fastener breaking.
You could also try using an extender bar. These are special bars which fit over the end of your spanner extending the shaft so there is more leverage and force applied to the fastener. It’s not advised to use two spanners to lever each other as it’s very easy to break them this way.
If the corrosion is extensive, use a wire brush to remove the worst of the corrosion around the area of the fastener. Be careful not to damage the surface of the workpiece though. Vinegar, or lemon juice and salt, left for a few hours or overnight can break up the corroded material, making it easier to remove. Once the worst is gone, use penetrative oil as above.
Using a blow torch to heat up the fastener and then allowing it to cool can break up the rust around the components because it causes the metal to expand and contract. This method reduces the hardness of the bolts and, obviously, it’s not a good idea to use it around flammable materials.
If the fastener is still not budging, mix up your own penetrative oil. A mixture of half automatic transmission fluid and half acetone creates a very penetrative mixture which you can leave on for a few hours before trying again with the spanner or breaker bar.
When attempting these methods, remember that it’s going to be easier to replace the fastener than the workpieces so if any damage has to be done, do it to the fastener!