My experimenting with plane sharpening has (like so many other things) caused me to research stuff on the Internet. I’ve been working on grinding the back on my older plane using sandpaper cemented down to a flat piece of glass. It’s still not quite there after about a solid 30 minutes of work, and it’s pretty clear to me that the grit is breaking down and not cutting as fast as when it was new. So, toward that end I started to consider the possibility of investing in some sort of grinding stone. But, I don’t know anything about them, so I started reading. That’s when I ran across this page, with tons of information and designs for jigs that can be used to help make sharpening quick and repeatable. I haven’t absorbed it (or even read it all), but I’m stashing this link for future reading.