This article features a metal saw arbor made from free-cutting steel. 

Article Number 44 shows the making of a metal-saw holder and 
Article Number 48 shows the making an arbor for a small slitting saw. 

The metal saw is a unique tool that is indispensable for some metalworking tasks.  I have used metal saws to cut a variety of materials, such as steel, cast iron, aluminum and brass.  Cutting has been done with and without the use of cutting fluids.

The below saw has 100 teeth, a diameter of 63 mm, and is 1 mm thick.  A design feature is the recessed mounting screw. 

"Flats" have been added for gripping the arbor while tightening the screw.