Originally Posted by
guy153
I've "reamed" HTs with emery cloth wrapped around an aluminium drum with a slot in it run in a drill. A bit redneck but so long as you get a good fit without the cup spinning that's all you really need. But I'm sure your milling will be more ideal.
I'll bet that you've never reamed a Paragon head tube with that method. .5mm doesn't seem like much, but it would be an eternity to remove with emery cloth. Its a bit of work even with a sharp Park tools reamer.