A heat-treating furnace has: a rotary shaft; a rotary bottom surface pivotally supported by the rotary shaft and rotates; a plurality of workpiece storage chambers arranged on the rotary bottom surface in a multi-stage torus configuration around an axis of the rotary shaft as a center; a hollow bell-shaped hot-blast guide disposed in a center of the torus configuration on the rotary bottom surface around the axis of the rotary shaft as a center so as to decrease a volumetric capacity in the furnace and to adjust a quantity of a hot blast fed in from above itself into the workpiece storage chamber on each stage; a furnace body bottom surface spaced away from the rotary bottom surface; and a furnace body lateral surface disposed on the furnace body bottom surface.

A heat-treating furnace has: a rotary shaft; a rotary bottom surface pivotally supported by the rotary shaft and rotates; a plurality of workpiece storage chambers arranged on the rotary bottom surface in a multi-stage torus configuration around an axis of the rotary shaft as a center; a hollow bell-shaped hot-blast guide disposed in a center of the torus configuration on the rotary bottom surface around the axis of the rotary shaft as a center so as to decrease a volumetric capacity in the furnace and to adjust a quantity of a hot blast fed in from above itself into the workpiece storage chamber on each stage; a furnace body bottom surface spaced away from the rotary bottom surface; and a furnace body lateral surface disposed on the furnace body bottom surface.

A fire pit has a combustion chamber with a perforated floor, a chute below the perforated floor directing ash and debris from the floor to an area below the chute, and a removable ash pan occupying the area below the chute and having a handle affixed thereto.