I really need one of these. I sharpen knives as kind of a hobby income, i.e. it's a hobby that produces some income to support my hobby. :-) It's high on the list of tools I'm going to buy next time I have a little disposable income. It's not just knives- I think it would be a very versatile machine in the shop.
You did a very nice job with your build. Thanks for sharing.
Another tool to make at some future date.
I stumbled across a Facebook group about them that you likely know about. There are various sources, designs and motors discussed. But it has the usual Facebook annoyances.
https://www.facebook.com/groups/847488865357217/