Yea, you should maybe view the recommendations as guidelines for what to shoot for when you have a really tiny bevel. And sometimes the recommendations people give are like razor measurements....
I aim more for Kono FM thickness when I thin. Those other ones are chonky, although if you mostly cut soft stuff and find food release / indestructibility desirable, the thicker measurements could be good.
Probably any of the reputable knife stores would do a good job. E.g. JKI, Strata Portland, Carbon Knife Co. I thought there was a new fancy knife store that opened up in Chicago, but can't remember the name. Anyway, I'm sure there's someone in Chicago that could do a good job. Maybe a local can weigh in. Or you can send them to
@Runner_up or
@Forty Ounce.
Don't try to maintain a 5 degree angle. That's impossible. Do it all with finger pressure. If you keep your fingers pretty near the edge, metal will tend to be removed right under your fingers. If you move your fingers back a little, you'll remove metal there. Look frequently at the scratch pattern on the underside of the knife to verify that you're removing metal in the correct place. Don't worry about getting it perfect. 10 to 1, the convex grind wasn't perfect to begin with. Imo, it's much easier (although very time consuming) to create uniform convex geometry on stones than it is on a belt grinder anyway, which is what most of the makers are using, so as long as you pay attention you probably won't ruin anything. That said, I wouldn't practice on a $500+ knife at first.
Low/high spots that don't hit the edge are only an aesthetic problem, in that they make it hard to polish the knife evenly on bench stones. They will minimally impact performance, and may actually improve food release a bit. If you actually have a hole in the edge, then yea, you should thin/reprofile until the profile is fixed.
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In general,
@HumbleHomeCook's relaxed approach is good advice. I definitely found target measurements reassuring when I was starting out, though. Aiming for < .7mmish and < 1.2mm at the 5mm and 10mm mark will probably give you something that'll separate food reasonably well, and you can decide how to tweak them from there. Nowadays I never measure though. Btw, the nail flex test is an easy way to test thinness near the edge. If you want a thin edge that'll scream through produce, just take the blade and press the side of the edge on one of your fingernails. If the metal slightly bends at the contact point (you'll see that light reflects differently there), it's thin enough.
Maybe one additional recommendation: when thinning make sure not to f up the profile. The biggest mistakes I've made thinning have always been while thinning down to a zero grind, and then continuing to thin further. For instance, when you're working on the edge and thinning at the same time, the steel can bend from the pressure near the edge, effectively making you thin near the edge at something like a 0 degree angle, so that you end up creating part of the edge that's like aluminum foil. If you don't notice that you're doing that, you can end up with a couple mm of foil, which then breaks off, ruining your profile. I think it's a better idea in general to separating thinning and messing with the profile as much as possible. Try not to be creating a burr when you're thinning.
I think they're pretty flat on the blade road, but someone who owns an unmodified one can correct me.