Innovative Knife Grinding Jig

[JHCC]

I was watching a video about a Japanese bladesmith making kitchen knives, in which the smith demonstrates his version of a jig to hold the blades for grinding. Here are a few screen grabs of the relevant section of the video:

And here's my sketch of what I think is going on:

You can see in the video that the pipe is left round at the handles, but hammered flat in the middle; I suspect this both gives better clearance between the jig and the grinding wheel and also gives a good visual of the plane of the knife, making it easier to get the right bevel angle. There's also some kind of fill in the bit of pipe holding the tang, but I haven't quite figured that part out.

And here's the full video: 

 

[JHCC]

And naturally, there's a shot of that smith's son using a wooden version later in the video: