You know, it’s funny that you posted about those two sources. I’ve found them, too, and believe they are all one really needs to know about sharpening card scrapers. I really like the video with Elia on sharpening card scrapers.
More to the point, I think there is more disinformation about sharpening than there is useful info. People have made sharpening hand tools into some mystical ritual that requires special grinders, .0001 tolerances, etc. It’s ridiculous. Man had been sharpening hand tools with rudimentary implements for 10,000 years.
I subscribe to the KISS school of sharpening – whether it’s a card scraper, or chisel, or saw, or plane iron. I’ve been using water stones (250 / 1000 / 4000 / 8000 ). They work wonderfully – until your kids contaminate them with oil. Since that unfortunate incident, I’ve decided to go to diamond stones – at least as soon as I get the money.
Regardless, I sharpen by hand. I don’t use jigs except for plane irons – I use a common side clamp honing guide. I use Paul Sellers’ methods for sharpening chisels and gouges by hand.
The point is, people shouldn’t try to church sharpening up. Sharpening is another part of “working” wood. It’s not meant to be ruined by western, linear-reductionist thinking to try to take the human skill out of it. No one cares or will ever know if your edges are 37.259 degrees and have a perfectly polished surface. Elia’s video and Schwarz’s article are testaments to that. Simple, quick, effective – no machines required. That’s my style.