Mikie, about 640 wide seems to be a nice size, as far as I can tell. Well that's what I use, and no-one's thrown anything - yet. Up to 800 is probably okay, I think. Chas did a helpful page here to give a guide on how small a size file you can get away with too, if that helps. If you want to have a test go, feel free to pop into the "Site Updates etc" board and have a trial run. We can always delete it later.
Note to other mods: Left in General Woodworking in order to grab maximum attention to others in search of guidelines. :wink: