A Dremel is a versatile tool that can use a wide array of different bit types. The tool can be used for cutting wood, metal and other materials with the right bit. It can also be used to grind, sand or polish when using other types of bits. Changing the bits is designed to be quick and easy, but from time to time a bit may get stuck, requiring a few extra steps to free the bit from the collet.
Tap the bit and collet against a hard surface a few times to attempt to loosen the bit. In many cases, tapping will break the bit free and loosen it enough to be removed.
Heat the collet with a lighter for around 10 seconds in the area where the bit is stuck. The heat will often cause the collet to expand slightly and may unstick the bit. If the bit is still stuck, wait for it to cool before continuing.
Spray some penetrating oil into the collet to lubricate the contact between the collet and the bit. Allow several minutes for the penetrating oil to loosen the bit.
Loosen a pair of vice grips, place them around the end of the bit and tighten them until they are clamped tightly on the bit. Wiggle and pull the bit until it comes free.