I've done that a lot, too. Depending on how close you get with the saw, it's not that big a deal to grind the angle true with a belt sander. A 6x48 mounted vertically is great for that. My goto belts are 60 grit, but you could even go a little courser just for weld fitup. Be sure your table is square to the belt platen. Good quality aluminum oxide belts will last a long time, while cheap stuff will just frustrate you. I can't speak to contamination, there are belt cleaners that work nice to remove loading. I suppose you should change belts for different materials, but I never do. I've never had a problem welding aluminum that was ground with a belt that had ground steel. But it's not like I do aerospace X-rayed welds, either.
Originally Posted by posixPilot
Long arc, short arc, heliarc and in-the-dark!