looks good--you could mill or file a couple flats on it to use a wrench to hold it while snugging your screw tight--it looks like your blade is on backwards for the teeth to cut, but my eyes may not be the best--Dave
Correct, it was a broken blade just for testing..looks good, But looks like that blade might be missing a couple of teeth.
Aluminum would be my last choice of material for an arbor, steel and even alloy steel is more to be desired.