What is a Stripped Allen Head Screw?
An Allen head bolt is a screw with a hexagonal socket in its head. This screw could be installed with an Allen key (also known as a Hex wrench). A stripped Allen screw occurs when the screwdriver grinds away the drive part of the screw head. Once the drive part of the screw is worn away, you will not be able to drive out the screw. One of the best ways to avoid this is to prevent the driver from spinning without the screw turning with it.
What are Allen Head Bolts Used for on a Mountain Bike?
Allen screws are mainly used for rebuilding and adding accessories to a bike. Many bikes also use Allen head bolts to join different parts of the frame together, as well as secure essential equipment, including brake pads, seat saddles, and derailleurs.
How to Extract a Stripped Allen Head Screw
There are various ways that you can get out your stripped Allen screw, as listed below.
You can use this method if the head of the fastener is exposed, and it is not going to break off. You will then use a pair of locking pliers for grasping the screw head firmly. Once the pliers grab the screw firmly, the head will dent slightly. You can then spin the screw head with the pliers until it is loose enough to remove with your fingers.
Turn It into a Different Drive Style
You will indent the screw head with this technique. The first step is to choose a driver style and size that is similar to the original one, but slightly larger. You will then place the screwdriver into the head of the screw and tap it with a hammer. This will indent the driver into the screw head, and you will get more screw engagement. You need to tap only hard enough to seat the driver and to cause a small dent in the head of the fastener. You can then press firmly and back out slowly. If you have a thread that is severely stripped, you can use this technique with a slightly larger different driver style.
Note: This method may cause damage to your screwdriver.
Make it a Flat Head
You can easily use this technique, and it will work if the head of the screw is exposed and intact. You can use a Dremel rotary tool and cutting wheel, file, or saw to cut a small groove into the screw head. As soon as the groove is deep, you will then use a standard flat head screwdriver to unfasten the screw. You should make sure to press firmly with the screwdriver and remove the screw slowly. This method will lead to irreversible damage to the head of the screw.
Note: You may risk breaking the head of the screw if it is too thin or the groove is cut off-angle. You may also damage your work surface with this method.
The video below (courtesy of Dremel) shows how this can be done:
Final Comments- How to Get a Stripped Allen Head Out
Getting a stripped Allen head screw out may seem daunting at first, but with the right equipment, it should be quite easily done. Just make sure that you take all necessary safety precautions when working on your bike!