Totally agree with you. I have people that come into the shop at work and try to use our scissor sharpening wheel to sharpen their knives. It ruins them every time. It is a small grinder with a very fine sharpening wheel on one side and a buffing wheel on the other. It is set at a exact speed for the brand of scissors that we issue to employees and it has a clamp that holds and keeps the blades at an exact angel. If you know how to use it correctly is will sharpen scissors in about 2 minutes and they will be extremely sharp.
They come in thinking it will get their knives just as sharp. The clamp will not work with a knife blade so they have to do it freehand, which means they can't possibly get the angle right, or close on one side then a totally different angle on the other.
Then they bring that mess to me and as long as they didn't grind away half the blade I can usually get it back in decent shape unless they let it get too hot you can tell right away most often by how it looks or sometimes it will still be blazing hot when they bring it to me. In those cases I will not even try. The kit and stones I use are mine lol the company did not buy them. Not wasting good stones on a blade they will never be the same again.
Best knife angle for sharpening are between 17 to 30 degrees. Most would be at 25 degrees. !7 degrees is really more for razor knives, fillet knives ect. Super sharp but not durable enough to cut something like even cardboard. Even using it for something like cardboard would dull it very very fast. 20 degrees is IMHO almost the best for kitchen knives. Super sharp and just a little more durable so in the kitchen it holds up pretty good.
My favorite angle is 25 degrees. With a 5 stone set and a kit or anything to keep you at the correct angle you can get a super sharp edge that will hold it's sharpness extremely well. Cutting most normal things when at work, hunting, fishing,and so on. It is just a really good angle to leave enough metal to keep that edge hard. Every carry knife I own is sharpened at that angle.
30 degrees is really good too, I just never seem to be able to get it quite as sharp as at 25 degrees. If I could I would use it constantly. From 25 to 30 I guess is just a matter of taste I guess..
LOL sorry for rambling on and on. I have been collecting knives all my life. I have more than I can even remember. My daughter has a nice collection as well. I have tried almost everything known.
What I posted works for me, maybe someone will find it of use.
As far as sharpening. From a beginner to someone 50 years old with a couple of hundred blades there is an excellent sharpening set that I found years ago and I still use it today. It makes it almost impossible to miss your angle and the stones hold up well. I will post the website if anyone might be interested. A lot of you may already know of the company. There are also sever other companies now that have a very similar kit, so they probably work as well. I just stick with these guys because of many years of good stones and service as well as advice.
The name of the company is Lansky Click here to go to Lansky Website
This is the kit I have been using for several years now, I do keep a much larger bottle of oil. A new set lasts me several years so I usually just order another kit if a couple of stones start wearing too much. Lansky Deluxe 5 Stone sharpening system.