A general rule of thumb for inserted tooling concerning nose radius and DOC (depth of cut) is the DOC should be equal or greater than the nose radius. So if you want to take a lighter cut you would use a smaller nose radius. As always the rule may not fit reality. There are negative rake inserts that have a positive cutting edge that work great for what we need. Positive rake tooling is not necessarily required to get good results. The biggest trick is to find inserts that work for you without wasting a bunch of money on ones that don't which ultimately end up sitting in the tool chest unused.
Here is my list of what works for me:
Circle Industries QCBI-375-6-5R Carbide Boring Bar w/TPCH-2205-CG5 Inserts. Bolt counter bores.
Circle Industries FCBI-250-4-5R Carbide Boring Bar w/TDAB-505-CG5 Inserts. Pre-boring chambers.
Kennametal E08SDUPR2 Carbide Boring Bar w/DPGT2151HP KC5010 Inserts. Sharp high positive insert. Crowns, cones.
Kennametal SDJCRF082D Turning Holder w/DCGT2151HP KC5010 Inserts. Sharp high positive insert. Relieving root of tenon at shoulder for recoil lug clearance.
Iscar SWAPR-1414-06 Turning Holder w/WPEX060402R08 IC908 Inserts. Finish turning tenons.
Seco MWLNR-10-3A Turning Holder w/WNMG060408-M3 TP200 Inserts. Facing and roughing tenons.
Iscar SER0625H16 Threading Holder w/IC908 coated inserts. Threading tenons.
