NOT following my own advice, I didn't trace the cover plate onto the floor first. This first hole is placed correctly. Using a hole saw leaves a rounded corner that reduces stress, but it's probably not significant. The farther back the rear edge is, the more likely you'll cut the tank or the vent hose.

A slitting chisel in an air hammer is a FAR-BETTER way to cut the hole, and doesn't require any prep.

Owner caption June 2009 · Photo 2663 of 5000