Let me take you back a few months, right after Thanksgiving, the question came up again. It was "What do you want for Christmas?" As I have done in the past, I took a black Sharpie and circled several items in the Lee Valley Christmas catalog. I never thought any more about it, but the person that drew my name gave me everything I had circled, I had expected as in the past they would select one or two items and be done with it. (If I'd known I was going get everything I circled, you can bet the bevel up jack plane would have been circled. :-) )
Well, one of the things I circled was the aluminum straight edge. My benefactor saw the steel straight edge guaranteed to be accurate to +/- 0.001" or some ridiculous thing like that, so I got the steel one. Fast forward to today . . .
The work bench I built last year has a 24"X72" maple top., I was going to make the top, but the finished top was considerably cheaper that the wood cost to build it, and besides the finished top was dead flat! I don't know how it happened, but the straight edge ended up on my dead flat work bench and Gasp. . . . . ., I could see daylight under the straight edge! Well, this won't do. . . I slipped a sheet of paper under the straight edge . . . it took three sheets to fill the gap. I break out my garage sale micrometer and can you believe the bench had (note the had) a 0.015" low spot in it.
Well, this was just wrong. That means the rocking chair I built earlier this year doesn't sit flat on the floor, after all I had leveled the chair on my dead flat bench. So I spent 2 hours with my jointer hand plane removing translucent shavings from the top. I gave up when the gap got to be 0.008", then I got to thinking,
It is all Lee Valley's fault, because if that darned straight edge had not been in their catalog, I would never have known the bench top was not dead flat.
I'm glad that I'm not one of those anal old fuddy-duddies that permeate the woodworker ranks :-)