I inherited a load of tools from my father. Among them was this bit. I have never seen one like it, and don't know its purpose. It has six straight splines set at an angle to the long axis of the bit and sharpened to act as cutters. The diameter at the splines is 1/2" and at the smooth shaft slightly less than that. There is a hole in the tip that is 1/8" deep. The first half or so of the hole is conical, and the deepest part is cylindrical. I do not see or feel any threads in the hole. The following is stamped into the smooth part of the shaft: "National Detroit High Speed IVF [those three letters are slightly obscured from wear, but I think that's what they are] 1/2 [which must be the diameter]." It will cut into the edge of a piece of wood if put in a drill press with the wood pressed against the rotating bit, but the cutting is slow.

I inherited a load of tools from my father. Among them was this bit. I have never seen one like it, and don't know its purpose. It has six straight splines set at an angle to the long axis of the bit and sharpened to act as cutters. The diameter at the splines is 1/2" and at the smooth shaft slightly less than that. There is a hole in the tip that is 1/8" deep. The first half or so of the hole is conical, and the deepest part is cylindrical. I do not see or feel any threads in the hole. The following is stamped into the smooth part of the shaft: "National Detroit High Speed IVF [those three letters are slightly obscured from wear, but I think that's what they are] 1/2 [which must be the diameter]." It will cut into the edge of a piece of wood if put in a drill press with the wood pressed against the rotating bit, but the cutting is slow.

I inherited a load of tools from my father. Among them was this bit. I have never seen one like it, and don't know its purpose. It has six straight splines set at an angle to the long axis of the bit and sharpened to act as cutters. The diameter at the splines is 1/2" and at the smooth shaft slightly less than that. There is a hole in the tip that is 1/8" deep. The first half or so of the hol is conical, and the deepest part is cylindrical. I do not see or feel any threads in the hole. The following is stamped into the smooth part of the shaft: "National Detroit High Speed IVF [those three letters are slightly obscured from wear, but I think that's what they are] 1/2 [which must be the diameter]." It will cut into the edge of a piece of wood if put in a drill press with the wood pressed against the rotating bit, but the cutting is slow.enter image description here

I inherited a load of tools from my father. Among them was this bit. I have never seen one like it, and don't know its purpose. It has six straight splines set at an angle to the long axis of the bit and sharpened to act as cutters. The diameter at the splines is 1/2" and at the smooth shaft slightly less than that. There is a hole in the tip that is 1/8" deep. The first half or so of the hole is conical, and the deepest part is cylindrical. I do not see or feel any threads in the hole. The following is stamped into the smooth part of the shaft: "National Detroit High Speed IVF [those three letters are slightly obscured from wear, but I think that's what they are] 1/2 [which must be the diameter]." It will cut into the edge of a piece of wood if put in a drill press with the wood pressed against the rotating bit, but the cutting is slow.