David Weaver
Hi, Wiley - I think all of these things are biases for the maker. If you're going to make an iron by hand, you can either make it perfectly (which is extremely unrealistic) or bias it so that even with error in manufacturing or movement in the wood being used, the bedding will still occur where you want it.

I like to hollow the back of my plane irons, as I did with the skew shooter. This probably isn't realistic for modern irons as I'm not sure how it could be mass produced without hammering.

AT any rate, looking at my japanese irons, they are concave along their length on the front and across the width on the back. I'm sure those things arose out of finding where you want the contact points to be (or the bias for sharpening) and making sure the biases guarantee them.

On wooden planes, I bias the fingers of the wedge at the bottom a tiny bit, but try for a more even fit in the abutments. Once things are pretty good, the plane is like a vault with the older irons (but the older irons are also sometimes a little irregular - even wards - and require work on the bed of a plane to get the contact points in the right place.

I guess where raney would call all of these details complicated (vs. someone drawing lines and living in a world of perfectly straight lines and flat planes) but to someone who is looking for a result, consistently, they just seem like common sense.

I asked Rob at one point how they managed not to have irons high centering on BU planes on the machined area since it's so much easier to bias something like that hollow, and his response was that the area looks like it's machined flat, but the beds of the planes are biased, too (The finished area is a bit hollow in the center).

one last thing for these biases - early on, I bought older stanleys because the machining on the frog was just "common sense - they're better, there's more contact area"....I've come to have a bit of a preference for later planes because the large adjuster wheel usually makes them less effort to adjust. The frogs have a small belt sanded contact area that I'm sure is not machinist flat. But the irons bend with the cap iron applied and they work like a treat---and are often new enough that nobody has worn them out or battered the soles (the cast is often soft, too, and they're easier to flatten and file).

All of these things are the little treats of making. There's a whole little area of what is (vs. what looks good and is popular) in guitar making, too. I can make a fender style guitar that will make someone's ear itch near the neck joint if the strings are strummed, but it requires the little biases and moving things around in our favor. Those are usually lost in production. Much of the human element in guitar feel has been lost in the consumer ranges, too - you get a very neatly made guitar cosmetically and 80% are kind of dead sounding and you get neck profiles that when you wrap your hand around them (they used to be finished on a specialty belt sander and felt by a "neck guy" or "neck girl" until they felt good), you feel stuff that just makes you think "I guess the CNC file can make them all identical, but the "neck guy" or "neck girl" would've never let a guitar that feels like that leave the factory.