What is the correct/best method to glue together two surfaces of made
from polyester resin with epoxy glue? This is a structural bond not a
cosmetic one.
Will roughing up the surfaces with 180-grid sandpaper and then
cleaning with acetone be ok or do I need to do more than this.



I have not done exactly what you are describing, but when sanding cured
polyester in preparation for bonding with epoxy -- say for doing an epoxy-glass
repair to a polyester boat -- I would probably sand the polyester with 50 or
100 grit (probably 100 if the surface was already smooth). If the surface had
any wax on it or anything else that might affect the bond, I would wash it
first, wipe down with acetone, and then sand it. I would probably change
sandpaper at least once if the surface had wax on it. I am not sure that
wiping down with acetone after sanding buys you much.
Alexander "Ali" Meller
http://www.sailing.org/int505/