Cutting Along X Axis vs Y Axis is So Loud

[rcar1046]

All other things being equal, does someone with more experience than me know why cutting along the Y axis would be buttery smooth...or quiet at least, yet along the X screeching and loud?

This video surfacing brass shows what I mean. And particularly along the top.

[JamesC]

I've found a 400mm feed rate with a .5 depth of cut and a 1.0 stepover makes the machine run (relatively) quiet. you might also want to get your tool deeper into the collet... the more you have hanging out, the more vibration you will get.