The invention relates to a reel-up (1) for receiving and winding into a roll (5) a paper web (W) that arrives from a drying cylinder (2) in a paper making machine. The reel-up (1) comprises a rotatably mounted reel spool (4) onto which a paper web (W) can be wound to create a paper roll (5) of increasing diameter and an endless flexible belt (6) mounted for rotation along a predetermined path of travel such that the flexible belt (6) forms a loop. The flexible belt (6) is positioned adjacent to the reel spool (4) to engage the paper web (W) against the reel spool (4) during winding such that the flexible belt (6) is deflected from the predetermined path of travel when the paper roll (5) starts to build up on the reel spool (4). The flexible belt (6) is air permeable and at least one blow box (7, 8, 9) is arranged inside the loop of the flexible belt (6) such that an underpressure can be generated that draws the paper web (W) against the flexible belt (6). The at least one blow box (7, 8, 9) has at least one nozzle (10) through which air is blown out of the at least one blow box (7, 8, 9) and the nozzle is shaped as a slot. According to the invention, the at least one blow (7,8, 9) box faces the flexible belt (6) with an outer surface (11) which is convexly curved such that dust which has been sucked through the flexible belt (6) and lands on the at least one blow box (7, 8, 9) is helped by gravity to glide along the outer surface (11) of the blow box (7, 8, 9) and fall of the blow box (7, 8, 9).