Thanks Brian, I think you're right. I emailed the place I bought the bar from and they said the minimum bore diameter is .58 and I was trying to bore .55. I opened up the bore to .6in with an endmill and did fine but the finish was still bad. I tried a different chipbreaker and it left a nasty finish, then I tried the chipbreaker in the picture again with a new insert and it cut great. It was quiet and and left a long thin piano wire chip but the finish was still no good. It looked like it was finely threaded with little ridges all the way down. I kind of figured it was because the IPR was too great for a fine finish. The minimum IPR for this insert is .004 IPM which is what I was doing so I'm think maybe try a different insert that is made for fine finishing. I also cut the boring bar from 6in. overhang down to 3in.
Any suggestions for a 21.5x or 32.5x insert (I have bars for both insert types) to get a fine finish in hardened alloy steel?