I get frustrated trying to sharpen the Fisher type stock finishing tools(scrapers). They are only about .050" thick, am trying to keep them perfectly perpendicular to the surface (top of a band saw), using 400 grit sandpaper. Any thoughts on that process would be most appreciated. Merry Christmas and thank you. Gil

Ruby stone Arkansas stone one fine stone of each

I don't know what those tools look like. Are they scrapers? There are some jigs for sharpening scrapers, if that's the case.

Those scrapers are really hard. I've seen people use a grinder to sharpen them. You want to get a burr raised on one or both edges. some use a file to do that too.

I've always accomplished that with a burnisher to raise the burr.
That's what Jerry told me to use.

Mark11, I use hard Arkansas and fine ruby stones to sharpen gravers they are pretty hard the ruby stone works great for polishing carbide gravers I'm sure this is apples and kangaroos, for scrapers I use a hardened steel rod

For wood scrapers, this works fairly well for flat or convex edges.

https://patents.google.com/patent/US5461943

This is a great start--I should have clarified--yes the scraping tools. Gil