Back to carbide .I have a lathe boring bar with about 5- 6 inches of reach made from an insert drill bit used for boring wrist pin holes in automotive pistons. That bar is solid carbide that is not possible to bend . It runs on a Aloris type tool holder .I made all that stuff not unlike good ole Burt but I certainly have a better choice of methods than he had . I might mention I inherited some of my machinists tools that have been through four generations going back to my great grandfather who took a boat ride from England to Ellis Island the first decade of the last century .As for the ability to do it that was also inherited .It's in my genes evidently .