The new mechanism with a rectangular feeding motion promises consistent feed of materials of all thickness without stitch gathering. The lower orbit of the feed dog prevents the material from flopping and reduces operating noise and vibration. The automatic lubricating mechanism helps improve maintainability, The machine is provided with a sub oil pan and double filter to keep dust from entering the oil. The machine is equipped with an adjustable bottom-feed while keeping the needle feed fixed. This prevents uneven material feed without changing stitch pitches.