Great tutorial! I found this in a search and didn't think to check the post date before writing a comment, so it's probably old... Anyway...
I have recently been planning a cabinet that will include spline mitered doors. I have seen the tutorials for making this joint on a table saw, but I am in a bandsaw-and-hand-tool-only shop at the
moment. I like the idea of using a spline the width of the kerf of a saw, however my only decent back saw is a Japanese saw with a ridiculously small kerf! I'm not sure if a spline that thin would give much strength to a door frame. I'll have to try your method of using a chisel and two saw kerf to clear the slot.
Also, to the commenter who mentioned their japanese pull saw wandering - I have this problem too! My standard panel saw cuts straight, but for a long/deep cut I can't get my pull saw to stop following the grain. It's so flexible that even if I try to correct the twist once it's started I can't! So I don't use it for long cuts anymore. It's still great for shorter/shallow cuts, though.
And maybe it's just the wood I'm using. This is my first real project, and I chose red oak because it is cheap and available everywhere. After working with some other hardwoods in some side projects (Walnut, beech), I wish I had chosen a wood that is a bit easier to work with you hand tools. Next time... Walnut is so lovely to work! It's like it *wants* to be smooth.