A thread feeding buffer for feeding a fibre thread (15) from a magazine roll (14) to a feed apparatus at a robot arm which is freely movable in the room. The thread feeding buffer comprises thread brake means (16, 19, 20) and at least one movable thread guide (17), on which a thrust force is acting. The thread is running from the magazine roll (14), via the brake means (16, 19, 20), through the thread guide (17) and further on towards the feed apparatus in such a way, that the thrust force acts for creation of a thread buffer between the brake means and the feed apparatus, which buffer is variable in length. At least one guide rod for guiding the movable thread guide is provided with means arranged to cause a braking effect on downward movement of the movable thread guide for preventing entanglement of the thread fed through the movable thread guide following a rapid fall of said movable thread guide.