I'm absolutely loving the surface finishes I'm getting on the underside of these trucks!
My thinking has changed quite a bit on speeds and feeds in general for machining, and though most of it makes intuitive sense, it is still a bit difficult to overcome sometimes. I'm finding that there are precise times and areas you want to use lower vs. higher RPMs and feedrates. And if a part is squealing, sometimes to fix that, you have to speed the machine up.
There are particular kinds of chips I've found that seem always to produce amazing surface finishes. I'm not sure if it's entirely related, but whenever there are long, wispy strands of aluminum (similar in appearance to hair, just thinner), I've always gotten a very linear clean finish.
Trying another form of after-machining finish on another truck, which is tumbling them in walnut shells. I didn't know this, but apparently, walnut shells have some quality that cleans up and shines certain metals. My boss had a bunch of dry finish shells leftover from a previous project where he said he could get a chrome finish on a stainless necklace for his wife.
I'm really interested to see what kind of a change it will do to these trucks and if it's possible to get anything close to a mirror finish. From what my boss tells me, it also takes quite a bit of time for them to run, so it may be a few days before I get a decent result, but I'm excited!