After prolonged use my metal saw became worn and needed replacement.  The new blade  has  72 teeth,  a diameter of 70 mm, and a hole size of 24.5 mm, different from my old saw. 

A new holder was made to match the bigger hole size.   Its design follows the design of the saw arbor described in Article Number 17.    
1. Machining the CAP from free-cutting steel, diameter 30 mm.

See 7.5, below for an exploded view and the names of  the individual  parts.

2. Using saw to check fit .   A neat fit with no play is  ideal.
3. Drilling 6.2 mm hole in CAP.
4. Trimming  CAP while copper foil protects machined surface. 

5. Counterboring  CAP for head of locking screw.
6. The BODY (SHAFT side) has been drilled and tapped to match threads of shaft.  

The material is free-cutting steel, diameter 30 mm.
Exploded view of arbor.
7.  Machining  SHAFT from free-cutting steel.  Blank size of 14 mm is turned to 12 mm  and threaded to mate with the BODY.  

8. The BODY is threaded onto the SHAFT and locked with high strength adhesive such as Loctite  2760.

A fixed steady supports the BODY during  boring.

See Article Number 37 for more on the Fixed Steady.
9. After machining BODY, cut off excess and face end of SHAFT.
10. Completed.
11. Back view of the holder.
12. The new one is on the left and the old one on the right.