-
I don’t know for sure but it reminded me of that video I watched yesterday about how you get a better finish milling from the bottom up rather than from the top down, (it’s for a sphere in aluminium with a ballnose but the geometrical principles apply), because of better tool engagement when milling from the bottom up. It may or may not be relevant, but here it is.
-
Interestingly, the same video I linked above also discussed how parallel toolpath are not optimal for shapes with very different slopes in them, because of the way it handles near-vertical faces versus near-flat faces differently, causing large visible steps (unless using a microscopic stepover). I would think perpendicular passes would be better (albeit longer), but other finishing toolpaths could be explored too. I’m still a newb when it comes to picking the perfect finishing toolpaths for a particular piece, so I experiment.
-
Yes, 0.4" depth per pass is quite aggressive especially for slotting cuts, and especially with a 3-flute like the 201 which have limited chip evacuation capabilties. This is likely what caused the endmill slip, that said an endmill is not supposed to slip in the collet if the collet is is good condition and the endmill is nice and tight in there. Have you have other occasions where an endmill slipped ? If so, you may want to consider changing that collet (or at least trying another one).
3.b. you can typically either go for large stepover and low depth per pass, or low stepover but large depth per pass using adaptive toolpaths. I collected my thoughts on this in more details in this section of the ebook. But basically, if you are slotting, I recommend a max depth per pass of 50% of the tool diameter. If you go adaptive, things get interesting to watch but indeed, sometimes it’s inefficient (like the case you mentioned)