Professional knife sharpeners

The key is not being in a hurry. I see some people sharpening a knife and they're moving the blade at super speed as if they're going to get some kind of award for how fast they swipe it across the stone.

If you want to maintain a constant angle, you can do it easily by moving the blade slowly over the stone. Do it slowly as long as you need to until it becomes second nature and then you can go faster. Even after years of sharpening, I still move my blade relatively slowly compared to some folks who seem to be almost slashing at the stone when they sharpen.

If it takes too long to sharpen using this method, then you need a coarser stone to start with . Trying to sharpen a knife with a really fine stone takes a lot of patience. Unless your time is really cheap, you'll be better off getting a coarse stone and starting with it to get the bevels set and then only using the finer grits to polish/finish the process.

Looking back at the title of this thread, I suppose I should clarify that I do not sharpen knives professionally. I do sharpen (and do some minor repairs on) other folk's knives, and I have had people offer to pay, but I have never accepted any payment.

Slamfire said:

440A was a premium steel to find on a production knife

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44oA isn't generally considered to be a premium steel any longer and was pretty common on inexpensive import knives for many years. Kershaw and Camillus did a fine job heat treating it and got a lot out if it. It doesn't achieve as high a hardness as 440C, but it can be tougher and easier to sharpen and take a finer edge while being more corrosion resistant. It isn't as "cheap" a steel as many made it out to be, but it significantly was used for rust resistance and a fine finish as well as the cost savings in production and in avoiding warranty issues that a higher alloy might see.
https://agrussell.com/chart

Slamfire said:

why didn't US companies, such as Queen, use 440C

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A and B are easier to grind, very rust resistant, took a razor edge, easy to sharpen (even if it didn't hold it long) . There's nothing exotic about 440 A or B, they just have properties and costs attractive to some manufactures. As to Randall Made's stainless knives, they use B because it gives them the corrosion resistance and better toughness that they're looking for. RMK doesn't push to get the hardness sat the upper range of what the steel will provide anyway so they get an even greater improvement in toughness and they're not as difficult to sharpen. You can get RMKs in 440C or they may simply make them when C is available at a good enough price.

A good system that controls the edge angle is going to outperform even a really good free-hand sharpener. It's just not humanly possible to control the edge angle by hand and eye as well as it can be done by a mechanical jig.

For something other than a straight blade instead of swept, curved, or recurved I'd agree completely.

OTOH, just about every custom maker I know of significant prowess is not using any of these systems. That's probably the difference between us mere mortals and these lords of the blade.

Good point. Probably the worst edge I've gotten recently on a factory blade was on one with a pronounced recurve.

I tried sharpening on conventional stones but the recurve wouldn't allow it. I ended up having to set the bevel with a diamond rod and finish it with a ceramic rod.

I've done exactly that.

This is actually pretty interesting. It is one of those problems where the solution seems intuitive but is wrong.

It's actually pretty simple to show that the intuitive result is wrong but even then it can be hard to get your head around the results.

I'll try an explanation, but then I'll provide a couple of videos in case my explanation isn't as clear as it could be.

Look at the KME sharpener from the side and you will see a triangle formed by the stand, the extension from the stand that holds the blade and the guide rod holding the stone.

It's important to look ONLY from the side (with the knife point aiming directly at you or directly away from you) so you get a 2D triangle to help visualize things. But why ONLY from the side? Because that's the only thing that matters. The angle of the edge bevel is ONLY important when viewed from the point of the knife so we need to limit ourselves to looking at the problem from that perspective.

Note that (assuming a perfectly straight edge on the knife) this 2D triangle is the same no matter where the stone is placed on the blade as the stone moves back and forth across the edge.

The distance from the stand to the knife edge (one side of the triangle) is constant. The distance from the extension that holds the knife upwards to the point where the guide rod goes into the stand (another side of the triangle) is constant.

The angle formed by the stand and the extension can't change. It's always 90 degrees.

If you look at the angle formed by the guide rod and the stand (viewed from the side) you can see that it doesn't change either as the stone moves across the edge. Remember we're assuming a perfectly straight edge on the knife--no curve.

Per the rules of trigonometry, if you have a right triangle (one angle 90 degrees) that has 2 sides and one other angle that never change, then other angle doesn't change either. That's exactly what the 2D triangle is in the case of a knife with a straight edge.

What it comes down to is that the curve of the blade will result in some tiny variation of angle as the stone moves across the blade edge, but the length of the blade won't change anything. And, as long as the blade is clamped into the fixture in the same position every time, the tiny variation due to the curve of the blade will be consistent. It will vary the same way every time.

Here's a good video on the topic that may be easier to understand than my trig based explanation.



Here's another one from a guy who initially thought the angle changed but then looked a little deeper.

This starts to get more complicated to visualize when you start talking about edge curvature, but I can tell you this. If the blade edge made a perfect and complete circle around the guide pivot area, the edge angle would remain perfectly consistent all the way around.

So let's think about curvature that doesn't form a perfect circle--in that case, yes, the farther the blade edge is from the guide pivot at the clamp point, the less edge curvature will affect the edge angle.

But what it really comes down to is that the only situations that have any chances of creating any practical difference in the edge angle are pathological cases. It's really not something to worry about at all. I can get a blade very sharp freehanding it and I'm introducing TREMENDOUSLY more edge angle variation into the mix with a freehand technique than you're ever going to get with a properly designed guided system and any reasonable scenario.

In other words, I probably wouldn't try to use a guided system to sharpen something like a long kris blade with lots of deep recurves. Other than pretty unusual scenarios like that, it's not worth considering.