Originally Posted by
ImanCarrot
..The material was held in a V-Clamp and was solidly held....
Both ends held in a V-clamp or just one clamp in the middle?
What diameter (width) bar?
If you have it held at only one point you have a tuning fork, aluminum is not rigid.
Feeding by hand on a manual machine or using handle jog on a CNC? Either way it is difficult to get a smooth feed and a surge causes a big chip that gets caught and things go downhill from there.
I have cut many feet of tee slot in 6061 with that type of cutter using 1200 rpm, flood coolant and a feed of about 5ipm, maybe a bit less. I always make the initial clearance groove .01 to .015 deeper than the bottom of the slot and always make sure the part is clamped in several places or held in a vise.
An open mind is a virtue...so long as all the common sense has not leaked out.