Larger arrows in xy

Question

I'm trying to make a poster, and have managed to enlarge math symbols in XY for my diagrams, but the arrows are too thin and unless you're right up against the poster, the arrow heads are almost invisible. Is there a good way to enlarge the arrows in xy?

Answer 1

If it's not too late, I would by all means design the poster at a much smaller size and then enlarge at printing. This is much more "natural" for the viewing situation at hand than enlarging font sizes etc.