So after finding some scrap aluminium, from a jewelery outlet so not sure of grade I decided to test some speeds and feeds. 1st one broke a new amana tool bit 
but the second worked fine.
They are 25mm in size for my daughter who is autistic and obsessed with her best friend turd, a plush emoji of the poop.
Been dying to try small metal cut outs and engraving.
Very cute she will love them!
What broke the first bit? I am about to get started on some aluminum myself…
To be honest I think it was my fault, I had it dialled in as a 2 flute by mistake and it was a single flute.
It looks like you were feeding too slowly on both of them, although the second was a lot closer. Aluminum is weird; if you go fast enough, then most of the heat from the cut leaves with the chips, while moving slower means that the heat stays there and eventually makes the aluminum start melting and getting gummy, and eventually clogging up your endmill and making a giant mess. And then it breaks.
6061 is relatively easy to cut and somewhat forgiving, while a lot of other aluminum alloys (all of the 1xxx and some of the 5xxx, IIRC) are much more likely to end up gummy if you’re not doing it perfectly. I wouldn’t be surprised if you have one of the trickier alloys there.
Cool project, though.
With the first one the waste was coming out in spiral threads around 30mm long but the second was lots of teeny chips flying out everywhere.
And found out today it was 5251 grade.
