Milling Inserts and Boring/Turning Inserts

But then, TP inserts have the same clearance for turning and boring ---
Yes, and many holders do not hold the insert 90 degrees to the work, either. Negative insert mounting is common, and makes for a stronger setup, where the insert itself has zero degrees clearance, which makes it stronger. A lot of the setups we use were probably invented by we machinists for expedience, not by the manufacturers.

And I do agree, John, that there are now so many styles and sizes of inserts and holders that you can have a pile of random inserts and holders with none of them compatible to get a job done. I am constantly thankful that I have a bunch of HSS laying around to make what I need.
 
The shop where I apprenticed had no positive rake tooling at all when I worked there, only after I left in 1970 did they buy some positive rake face mills called "whisper cut"; the negative rake mills did make a lot of noise! They were against the idea of positive rake tools because the inserts had half the number of cutting edges --- saying nothing of the higher productivity of positive rake tools due to lower power consumption and the ability to take deeper cuts and the ability to attain better finishes. I constantly comment on people's gravitating to negative rake tools on this forum, where most use small low powered machines for whatever reason, including the old one about more cutting edges. The fact is that positive rake tools are much easier on the machines, and allow deeper cuts, and result in better surface finishes and usually better chip control.
And, also yes, HSS tooling is much more appropriate for the low powered machines, members seem to be resistant to learning how to grind them and go the easy (and expensive way) and use inserts, and talk of depth of cut expressed in small numbers of thousandths.
On my 9" Monarch lathe, I was using turning tools ground with simple straight relief angles, and cutting depth in steel was limited to about 1/16"; I then remembered how I was taught in school to grind a roughing tool for (mostly) use on 10" South Bend lathes such as the class had most of, it was an angled tool with a ground in chip breaker, ground on the edge of a 12" wheel; all the students were given a piece of key stock to practice on, and when he became proficient and presented the teacher with a satisfactory grind job, he was given a new 1/4" tool bit to grind and use (and keep) for the duration of the class. I ground several of them for my Monarch, and what a difference! Deeper cuts, and much better chip control! I also shortened the drive belt, it made a large difference also ---
 
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