[dgoddard]

I have been cutting threads with HSS ground 60 deg. Have started to use carbide inserts for most all other turning operations. Am looking at getting an indexable toolholder for threading. Notice there are two types, the MTVO which the insert is vertical and the another which the insert is horizontal. Will use on manual Clausing 1301 lathe and a Grizzly G602 which is being converted to CNC. Anybody have a recommendation as to which may be best?

[WOLOG]

I prefer the laydowns. I guess it is just preference. Use the one that will be cheapest on inserts if you are just hobbying around. If you are doing this for money, use the holder that will give you the greatest number of choices for thread pitches/forms. I think that the 3/8" IC toolholder/insert may be the most popular. Kennametal TopNotch is good too.

[dgoddard]

Just hobbying around. Machining is my replacement for boating and golf. Can't say that it's cheaper though. Cost of inserts is only slightly less for the upright (MTVO) so that is not a major factor. I have AXA QCTP so 3/8" IC is definitly best choice. Thanks for your input.

[PixMan]

I also believe you'd be best served by going with the ER16-size lay-down inserts. There are so many more choices for full-form and partial-form threads, plus general purpose ones and varying grades to get the right one for most any material.

Many of the "on-edge" styles are limited, and being phased out, with Top-Notch style being the exception. It's mainly the triangular ones going away because the ER style has one major advantage: the ability to change shims for lead angle.