The shank on this one is 5/32". The Rock does not have a 5/32" adapter. (Could use the ER11 adapter in the 1/2" Rock though.) There must be other ones with 1/8" shanks.
You know, one can get bits of any kind you want made in China. Maybe a bit with the 3/16" left at the top to hold but ground down in the middle for the clearance.
bergerud: I have always worked with cnc mills and it's driving me crazy be cause cant change feed and speed of the end mills I know if could change them would have less chip out and other problems.
I have use hog end mils two inch dia. and drill holes so small bit where all listed by letters I think the smallist I ever used was .011.