carbide inserts query for a confused wannabe user

[savarin]

The comment regarding depth of cut possible with my 9x20 set the bells ringing so I thought a few experiments were worth while doing to set my mind at rest.
The material is stainless, HSS tool
First cut at 10 thou"

No problems

Second cut at 15 thou"

Nice tightly curled chips and again no problem

Third cut at 20 thou"

Hmm, chips starting to string out but again no problem.

Fourth cut at 25 thou"

Danger Will Robinson, these chips or should I say strings were lethal but it cut it ok.
I didnt have the nerve to go thicker as I felt this was more than enough for what I will do.
So, end of experiment..... I wont worry about the lathe being able to handle any thing I will throw at it.

 

[Wreck™Wreck]

A bit of insight from someone that has been doing general lathe work for a living going on 30+ years, take it for what it is worth.

In general lathe work such as is often found in job shops and hobby shops there are only a handful of insert shapes that will cover the majority of common turning operations, pictured below are what I use the most on a daily basis.

WNMG Trigon for OD roughing and facing. Very tough, excellent for roughing down flame cut edges.

CNMG 80º diamond shapes of various sizes and edge shapes, turning, facing and boring.

VNMG 35º diamond shapes of various sizes and edges, finish turning and boring, working close to a center and shallow undercutting, they do not face well.

Internal and External lay down threading inserts. I also use some end mounted internal thread tools for small holes when needed.

Parting, in this case Kyocera.

Kennametal Top Knotch inserts, internal/external full radius grooving, internal/external straight grooving and internal/external threading, the inserts fit in the same holders, one can use the same holder to turn Acme, 60º V, Whitworth, metric 60º and metric trapezoidal threads just by changing the insert.

Assorted triangle inserts which I rarely use.