Ever bought a plane that has one side thinner than the other? I have and always wondered why it was like that. Of course early produced cast iron planes were made one at a time and just cast that way, but usually both walls were thin. The most obvious and most likely other explanation is that over the past 100 years some owner ground down one side to eliminate a blemish or some ugly imperfection, somebody's initials or name or something else that didn't please them. We all know that happened and still does today. OR maybe it came from the factory that way. But that being the case why does the finish look like it was done at the factory? A lot of folks don't believe that Stanley would sell a poorly cast plane. I disagree. Why wouldn't they?
I have a theory on that. So, they, Stanley, spend a bunch of time and effort making a casting that doesn't make the cut because the wall is too thin, if in fact their QC was that stringent, which I think is doubtful. (More on that later) Assuming then that it goes into a pile of rejects. Now, they can toss the rejects into the melting pot and start over or they can 1. finish it and sell it as a second or 2. make it available to employees at a discount who can then piece a plane together from other parts and keep it or sell it themselves to somebody. There are lots of different possibilities. Either way Stanley sells the product and makes a few cents on it. Still a profit. Doesn't it seem likely that they would want to make money on a plane that's "saleable" but not necessarily perfect? They were always trying to find ways to save money. That's why you find planes with parts that the type studies say are not correct for the type, you know, "leftover chicken from dinner two nights ago" business model.
Regarding their QC, Stanley was the biggest tool manufacturer in the world in the 1890s. They probably made hundreds of thousands of planes in a year and the times being what they were, big corporations like Stanley, US Steel, JP Morgan, Standard Oil, to say nothing of the railroad companies, pretty much ran the country the way they wanted it. There were no federal regulations on interstate commerce, consumer protection or anything else. The big companies made sure of that for a very long time until Teddy Roosevelt pissed them all off by getting some legislation to control their abuses in the early years of his administration.
So, you, Joe Carpenter, mail order a Stanley plane from your favorite hardware company and it arrives a month later with a thin side. What are you going to do? Not a darn thing except use it. You can't drive over to WalMart and return it, can't really send it back because it would probably cost more for postage then you paid for it and who knows if you'd ever get your money back or a replacement. Basically, Stanley didn't really need to have any significant QC because they were the only game in town and controlled the market, prices, inventory, shipping, just about everything from creation to delivery. You, Joe Carpenter, need a plane to make your living so you keep it, use it, and/or eventually sell it to somebody else. I'll bet that there were millions of second rate Stanley planes made over the years that made it into the market place and into the homes of folks like you, Joe Carpenter.
Now, WE find them once in a while and speculate on why the casting is thin.