I have sucessfully used the cone method many times. In using it some of the
tips I have are these:
 
Narrow end of cone should be 3/8 inch (bee space). Use a 3/8" bolt as a guide.
 
If you use hardware cloth cover it with  window screen material.
 
If you have some really smart bees you might have to use a cone inside a cone.
Larger one over a shorter smaller one ( I have only had to do this once in 10
years)
 
Hive on outside should be no more that 2 feet from cone.
 
Leave the cone on for at least six weeks.
 
I hope this helps anyone trying the cone trap out method.
 
Regards,
Ralph Harrison
Western Connecticut Beekeepers Association
Milford, CT USA