What tool do you use to modify a variator

[de dee]

   I use a 1/2 " belt sander,  black and decker calls them elec. files,  the sander belt is 13 mm. wide, perfect for a 12 mm. wide slider,  it took me about 1/2 hour to file out the eight slots, in my variator,  this is my second one,  I am making a spare variator,  with better measurements,  I now have multy grit sanding belts ,I start out with 40 grit, then I go to 80 grit,  and finish with 220 grit,

[de dee]

   I use a 1/2 " belt sander,  black and decker calls them elec. files,  the sander belt is 13 mm. wide, perfect for a 12 mm. wide slider,  it took me about 1/2 hour to file out the eight slots, in my variator,  this is my second one,  I am making a spare variator,  with better measurements,  I now have multy grit sanding belts ,I start out with 40 grit, then I go to 80 grit,  and finish with 220 grit,

  just looked up the tool   black & decker belt sander  PF 260   1/2 " presision belt sander from $23.00 to $35.00