I really don't have answer for you other than to get a socket that fits but what am I missing here?
So... to save yourself the possibility of wasting $11, you bought a $46 grinder? Why don't you just take the part into Home Depot and find a socket that fits it?
The socket wall is too thick for the space between the nut and the burr. The grinder seemed like the better bet, and in the end, I'd have another tool. I did take the part to Home Depot and scour the shelves for a socket that fit. There was a Milwaukee thin-wall socket set, but it was $70 and sealed in a box.
I bought an electric grinder about 10 years ago for $20 and it works great. This seems like one of those hipster things!
Ha! Can an engineer even be a hipster?
Our electric grinder broke after 4 years. This hand grinder is the conical burr type, which is the nice kind which can, at least with the upgrade, make a nice, even grind for French press. An electric one would cost more than twice as much, and I'd think it would be more likely to break and wouldn't be as repairable.
I found a friend at work who has a bench grinder, and he agreed to try grinding down the cheap socket I already have. He recommended that I keep the bench grinder I bought, but honestly, I'm not sure I would use it that much. He said it was good for axes and lawn mower blades, but I have maybe 2 trees and 1000 sq ft of grass in my "yard."