Alright... I've been using carbide tools in set screw tool holders for years. I've made my own for smaller tools when I was using nonstandard collet nose spindles for tools that were to small for the spindle. I've also made my own solid one piece tool holders with a setscrew.
I have to be honest. I've never really had an issue with using carbide round tools in set screw tool holders, but I am told that set screw tool holders "should only be used for tools with a flat." I do put the tool holder in a fixture and tighten the set screw with the maximum tool pressure I can put on a long arm hex key without stripping the screw (and sometimes stripping the screw LOL).
So, is it what I have been told true? Should I only use tools with a flat on them in set screw tool holders? If I do that then am I reduced to finding a way to put a flat on those tools? How would one go about that?
I'll probably ignore all that and just keep doing what I am doing, but I thought I'd ask.
P.S. I use almost exclusively carbide tools except for drills. I even have some carbide drills in sizes that see a lot of use. I have a few HSS mills, but I rarely use them.