Abstract: The invention is a combination welder's slag hammer and reamer. The slag hammer part of the combination tool may be of conventional design, that is, a handle, a shaft connected to and extending from the handle on one end of the shaft, a head connected to the other end of the shaft, the head having a sharpened blade on one end for knocking off the weld spatter. The reamer part of the combination tool may be anywhere on the hammer. Preferably, the reamer is on the head, at the opposite end from the blade. This way, the hammer handle may be simply rotated to use the blade end or the reamer end. Generally, the reamer is of cylindrical construction so that it easily fits inside the nozzle. Preferably, the reamer is tapered from smaller to larger from the end to the middle of the hammer head. This way, nozzles of different diameters may be cleaned by the same reamer. The reamer has facets or edges on its surface for scraping the weld spatter off the inside of the nozzle.