To set the rivets I used this process.
Take a big (# 10) flat head wood screw and chuck it in a lathe or drill press and then use an abrasive cut-off wheel in a Moto-Tool to grind a conical form.
A little bar of tool steel clamps the head of the rivet flush to the frame and the C-clamps apply pressure to the metal flange segments.
Your heavy duty Vise-Grip pliers then easily flare the rivet using your home made conical punch. (One C-clamp removed to take picture.)
The finished speaker sounds great and considering the original condition, I'm pleased with the appearance. It is surely not going to bring thousands on e-Bay but will do just fine in my Masterpiece III
