I have a variation in sound / vibration as while my mill is moving +x vs -x directions. There seems to be a higher pitch ringing and vibration when moving +x.
I am milling a piece of 1/2" birch ply with the 201 1/4" cutter. S/F are the suggested ones from CC.
Is a variation in sound normal? Do I need to tram the machine?
I think it is normal for each machine to sound a bit different. And for different sounds when moving different directions. The sound comes from a stackup of parameters in the kinematics chain that result in resonances. Change up the feeds & speeds a bit and the sound changes.
If you were machining microscopic parts at really high tolerances you might want to find a combination that has the least resonance. Similar to the way machines get tuned for very high-speed machining to get the best finishes.
For the stuff we typically do on these machines, I don’t think it makes a difference.
Now if it were awful grinding, rubbing noises I would be concerned.
You can play music using the stepper frequencies, and of course someone has made a midi-to-gocde utility. No matter how crazy the idea is someone on the internet has probably already implemented it:
Cutting back & forth like that (Zig-Zag, Lace, Raster) is switching from conventional to climb cutting on every other pass. Climb cutting tends to push the cutter away from the material whereas conventional cutting draws the tool into / toward the material. Of course if the machine is rigid enough you won’t have any measurable deviation, but the forces are still opposing & will create a different sound.