Indexable insert for S.S. and Titanium?

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H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Aug 26, 2014
Hey Folks,

Can I get some recommendations for an indexable insert I can use to thread some 7/16-40 pieces in 303 and Gr. 5 Ti? I've got quite a few to do, and the job is big enough that it's time to invest in some indexable tooling.

I'll need inserts and a 3/8" shank holder.



Global Moderator
Staff member
H-M Platinum Supporter ($50)
Feb 8, 2014
I would start here https://www.amazon.com/AccusizeTools-Indexable-Carbide-Turning-2387-2003/dp/B01NH9REZL/ref=sr_1_6?crid=31F3EHM9FKKNS&keywords=accusize+lathe+tool+sets&qid=1557453762&s=gateway&sprefix=accusize,aps,194&sr=8-6

I have found the Accusize insert holders to be a pretty good value. I use them both on my manual and CNC lathes. The only problem I have had is the 3/4 shank parting tool wasn't quite up to the task on the CNC lathe.

For inserts I have been buying from Shars. https://www.shars.com/products/indexable-cutting/indexable-inserts

I can't tell any difference in those vs. the high prices name brand names.


Active User
H-M Supporter - Gold Member ($25)
Jun 12, 2014
The 3/8" shank holder is limiting, also need rigidity. You might look at the Shar's holder, assume you want an external right hand.

Depending on the thread pitch, I would recommend a 16ER AG60 (A60 is for finer pitch), haven't tried the Shar's inserts but tried Cobra brand on a different threading holder and they broke very easily. On Lay down inserts I have been using Carmex (Iscar) and I have done quite a few threads with the same insert and still on the same cutting tip. I also have some Mitsubishi MMT VP15TF-16ER-AG60 inserts that I haven't used yet, they supposedly give cleaner cuts with less vibration. Might work better on SS and Titanium, you will need to take sufficient cut depth per pass due to work hardening of the metal. I prefer the lay down type inserts for threading, they seem to be more durable and I get very clean threading finish.



New Member
Jan 2, 2018
If you were machining lots of parts you’d use different grades of inserts for stainless and titanium but for small quantities most cheap coated inserts should do the job. And you can use these on other jobs in the future. There’s a HUGE range of shapes and grades to choose from. If you want to get your head around the world of inserts try this document over on the Bridgeport Mill group: https://groups.io/g/BridgeportMill/files/Insert designations and grades/DS30 - Inserts for indexable tooling.pdf (not sure if you need to be a member).

For threading, be aware that you might need left or right hand inserts (and matching holders) depending on whether you are OD or ID threading and whether you are cutting to a left or right shoulder.

Go for the largest holder your machine will take as this maximises the stiffness. And buy a holder that takes cheap and easily obtainable inserts rather than tie yourself to one supplier. The big name suppliers all produce excellent inserts that in my experience last longer than the the cheap no-brands, but for home workshop use this difference is minor compared with the cost.

Could I put in a plea to treat inserts as *recyclable* rather than disposable: save your worn out tips and mail them to a carbide recycler - tungsten is quite a rare metal and it’s a shame to send it to landfill!

AKA The Felsted Skiver


Active User
H-M Supporter - Gold Member ($25)
Dec 20, 2012
If you have a lot of stainless and Ti to do then it will pay to buy good inserts and a tool holder that beds the insert precisely. I would suggest looking at Carmex tools and their BLU inserts in particular. I think an AG60 laydown insert will work well, at least in my experience. A Carmex tool holder is $20.00 more than a Shars holder and if I were going to do a lot of threading then I would go for a known good tool holder and inserts.
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