Why put your steel mandrel against your bench for setting => 3 photos

 Here is a great idea and technique for holding your steel mandrel if your hands need that extra support.

 This additional support is quite essential when you are Bezel or Flush Setting. You need that support when both of your hands are fully occupied.

 One hand will hold the steel mandrel and the ring, while the other hand will hold the hammer. Between these 'holding techniques', you can now have greater support in getting the ring finished.

  I use a bur that you don't need, just hammer that bur into your bench at arm's height as shown here.

 It is preferable if the mandrel is an "extension of your bench peg", again, as shown here.

 Your ring should be tightly secured on the mandrel. Don't use this technique if you are attempting Pave' setting. 

Using a steel mandrel is the best & ONLY option.