Threading tooling

[Larry42]

I've been using hand ground HSS tooling up until recently. My projects have been getting more involved and I'd like to buy some inserted tools for threading. Which? I have an internal threading bar that works OK but now need external for both right and left. I would like some input on two basic forms that are available. The triangular inserts that are mounted flatwise and require two different inserts, right & left. OR the inserted tool holders that use inserts mounted edgewise, requiring just one insert that can be used either right or left. TNMC32NV Given that inserts are expensive the second choice has a lot of appeal if it works well. My lathe is a PM1440HD. 5/8" tools.

 

[Wreck™Wreck]

Triangular lay down inserts are either internal or external which makes them handed left or right, Kennametal Top Notch tooling is also handed.
End mount tools are not, if you want one insert for several tools use face mount holders.

One of the reasons that there are threading inserts of various leads is clearance angles and the ability to get close to a shoulder.

 

[mksj]

I have been using the triangular (TNMC) threading insert for external threading, as mentioned the same insert can be used for right or left threading. I have been using the lay down insert for internal threading with good results. Probably the biggest limitation with the TNMC type inserts is their fragility and durability. The cutting tip for threading is very fine and has very little support underneath it. They do make a TNMC tool steel insert that may be less prone to breaking (see link below) but they are pricey. I do find that the cheaper TNMC inserts, like Cobra fail much sooner then say Kennametal. The positive of TNMC is you can thread right up to a shoulder, the TNMC-32NV will cover an 8-36 TPI threading range.

A lay down insert has both internal and external configurations as well as left and right hand thread inserts. You also need to be aware of the various insert types with regard to their threading ranges. I am using 16ER-AG60 inserts for external threading and a 16IR-AG60 for internal threading, both have a TPI range of 8-48. I just purchased my lay down external threading holder to try on my more challenging metals so will see if that is an improvement over the TNMC. I purchased a Hertel Right Hand Holder, 3/4 Inch Shank Indexable Threading Tool holder, it the same as Iscar at 1/2 the price, it is the smallest shank size that I am aware of that will take a size 16 insert.
https://www.mscdirect.com/product/details/53438560

There is also the Top-Notch and DorNotch type inserts that are much more robust and expensive.

http://www.arwarnerco.com/p-252-tnmc-32-nv-55-degree.aspx

Threading insert comparison

 

[Larry42]

My internal threading bar uses 16IRAG60 inserts and so far has worked fine.
I like the idea of being able to thread right up to a shoulder with the edgewise style. I didn't realize the TNMC inserts would be fragile. 90+ % of my threading is right hand. I've stopped setting the compound to 29+ and just plunge cut, turning from the left to right. Much less stressful. Would need to buy a left tool holder to thread close to a shoulder on the right side.
Thanks for the input.