Tnmg insert suggestions


Active Member
Aug 20, 2018
Looking for suggestions for tnmg or tngg for turning a2 tool steel. Or maybe I dont need a 0⁰ angle...I really dont know. Also 331 or 332? I have a few lathe projects I want to work on, involving A2, and I've never turned it before, so all suggestions are welcome. One of the projects will have interrupted cuts, the other will not. The A2 is annealed. That's about all the info I can think of, at this


Active User
H-M Supporter - Gold Member ($25)
Jun 12, 2014
Really need to know some more specifics as to machine, Hp, current tooling/holders, etc. Negative rake geometry usually requires more Hp and rigidity. In either case, I would suggest something along the lines of a TNMG 331 (TNMG160404-TF) which is used for general turning for fine to medium depth cuts. I have been using Iscar inserts with an IC907 coating for most ferrous steels, this is a general coating with a wide application in many steels and even can be used in aluminum in a pinch. I use the IC907 in other inserts and it works great, the inserts are inexpensive and a box will last you years.

This is a possible alternative, the coating is for hard to machine steels.

Carbide Depot sells a ton of these TNMG which run from $5-7 a piece, you need to buy a box of ten. At that pricing, may be worth calling them. I use a lot of VP15TF coated inserts and it also holds up well.

Unfortunately, unless you buy from a major US supplier, many of the inserts are counterfeit. One reason why I recommend Carbide Depot which is only slightly more. Otherwise try the Iscar. Zillions of choices/coatings.