Thank you all for answering so promptly.??
The first reaction I had was, "Yes I need to grind the insert holder".? ?But before I did that I read again.? There are many references to the tool holder.? A tool holder means the iron you clamp in a tool post.? (HTRL p27 Figs45-50).? It also seems to mean the iron that the triangular inserts are screwed onto. (I am going to refer to these as "insert holders").? ? If the insert holder is mounted in a tool holder the angle of the cutter is raised, and the bottom corner of the insert holder comes into vertical alignment with the cutter tip. That seems to have been my problem.
I sorted it out by changing back to an HSS cutter.?
In future I will try to use HTRL Fig 50A - 10 in 1 holder.? ?This "detail" had not registered in my tiny brain before now.? I hope that I have learned something.
The inserts are advertised as TCMT, but the full p/n is not given.? ?I have now learned that there is much more to carbide inserts than I had thought.??
Thanks again to all who took the time to comment.?
