Why my Cuts are rough?

[oskar]

From the videos this is what I'd say first is planning your project step by step. I would have did the ends or sides first then would have slot the center out. With how you are holding the part any vibration is gonna make that part sing. Second is how it's being held. There's a lot of overhang in every direction. It needs to be rigid. Third you have,had a lot of overhang on your tool. Looked like a 3" tool. If your slotting shallow you use the shortest endmill. Even deep slots start with a shorty and work to a longer one to cut down on chatter and deflection. Fourth your feed rate looked alittle fast. I usually start slower see how things are acting and speed up as necessary. Using a stream of air at the endmill will help with chip removal along with some lube.

Nicely said, thanks for your time

Looks like my problem was too slow RPM and kind of fast feed. Next time I will know better

 

[benmychree]

What likely broke the cutter was chips balling up in the flutes, chips then cannot escape and the cutter breaks; lubricant such as WD40 or just plain kerosene or diesel fuel will help to prevent the chips from "welding" into the flutes, and as another wrote, an air blast would help clear the chips out.

 

[oskar]

I do use WD40 but maybe not enough and I prefer to use a shop vacuum to clear the chips instead of an air blast which splatter the chips.

With the good tips here hopefully next time I will have a better luck