End or side?
You say end so will it ever be asked to plunge?
If so the cut material is coming up.
A straight primary alone alone simply won't clear as it goes around the arc under the flute base.
Sort of the same thing in facet drill flute grinds. Without the second the back hits or you have to make the only front one really, really steep. To the point that is just about impossible to grind without hitting the next front guy.
The angle of grind is not the rotation of the tool so you run out of clear very fast.
It's hard to describe but if you only put on the primary with no second or other and then go to use it you will find this trailing back corner clear problem.
You don't grind the primary angle radially, you grind it straight. The tool works in rotation, not straight and it's the back ass before the next flute starts that is the problem.
I hope any of this makes sense..........It's a circle being cut and the grind is a line and plane.
Bob
(PS. rereading this post makes it hard to understand for me and I model this stuff all the time so....
talk)