After wasting my money on a less expensive but poor quality step drill, I moved up to this Irwin Unibit # 1 .  Yes, the Irwin costs more initially, but this Unibit cuts so smoothly that it rivals the precision of a chassis punch.  I bought this Unibit to drill 15/32 inch holes in steel sheet metal for mounting toggle switches .  This Irwin bit quickly cuts clean holes, with no burrs on either side of the hole.  Amazing !  I do drill a small pilot hole first, and I use a light lubricant spray as a cutting oil.  ( Hmmm...,maybe my lady friend will buy a whole set of these bits for my birthday !  )