OK, I checked my friend at Pathfinder leather, and his two machines are old; a Singer 29-K-71 and a Pfaff 345-H3-60, both treadle machines. He uses these daily, however not continuously. Between the two, he is able tosew almost anything. The Pfaff is the heavy duty, being used for holsters and other heavy jobs, up to 20-25 oz.