Uneven edge grinds

C

Cliff Stamp

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It seems like lately a lot of the edge grinds I see on knives are uneven, I don't know if this has always been the case as I used to do a lot of hand sharpening in the past, while now I do a lot of jig work, mainly as it allows a more consistent comparison.

Anyway, a lot of the knives have edges which are ground at very different angles, by this I don't mean 1-2 degrees which you would expect as most of them are hand sharpened, but large differences.

For example 25-30 degrees on one side and 10-15 degress on the other. This makes it very difficult to sharpen freehand, and near impossible with any kind of jig unless you reprofile.

At first I assumed it was just a random variance thing, however as I look back upon my notes, the vast majority of the cases are heavier on the left side (edge down, left side is facing your left hand). So it seems that there might be some way in which however these are getting sharpened that is giving them a consistent higher angle on that side.

I tried grinding a few bevels on a belt sander freehand, and it isn't difficult to get them decently even as you naturally hold a similar angle, it seems really odd to me when I grind a bevel like the above, I can feel one side so much higher than the other.

The only thing that I can think on is that the bevels are ground this way intentionally to hide a sloppy primary grind, because in the vast majority of the cases, the edge bevels are even in width so they look ok visually.

Any comments from makers who do a lot of machine sharpening?

(in regards to how the edges are measured, I set up a crockstick and adjust the angle until the scratch pattern hits the bevel evenly, this is checked under mag, as well as by eye using a marker, when you go to high you hit the very edge, when you are too low you hit the shoulder).

-Cliff
 
Cliff - first can you tell us if you're referring to custom knives or production knives?


Also, are you referring to the final bevel (the one set for sharpening)?

Are these mostly on flat ground or sabre-ground knives?
 
Custom and production, the final edge bevel, the one you sharpen. I have see it on full flat ground as well as sabre flat and hollow grinds. I have even seen it on convex blades with secondary edge bevels, but it is rare they have them so it doesn't come up often. Most recently on a small fixed blade from Dozier. Tried a few passes on a Sharpmaker, did nothing and then check the edge and found while the included angle was <40, the edge was very uneven and thus only getting hit on one side.

-Cliff
 
My knee-jerk response is that makers tend to favor one side over the other because they're all either right-handed or left-handed (vs. ambidextrous).

I'm curious, though, if this is being done intentionally on certain knives.
 
One thing that I have found helpful in knife grinding is to practice doing it left
handed and after a few years it don't make any difference, right or left. Also one thing that helps is to run the grinder the other direction when sharpening. I always sharpen with the edge up so I can see what I am doing and with the reverse direction it is a piece or cake to get the same or nearly the same bevel free hand. Gib
 
It doesn't bother me Kit, less than one minute on a 40 grit ZO belt and edges angles are even. Of course now the edge grind looks uneven, as one side is way wider than the other, but that doesn't bother me. In general though this is going to give an average user a very poor opinion of ease of sharpening of said blades. Plus while I could see letting it pass on production knives, if you are paying for custom I don't see it as being too much to ask, especially when you have companies like Spyderco which consistently do it right.

-Cliff
 
Yeah, and in this case, not funny, because it isn't bothersome. It would be amusing, had I for example came on as strongly irritated.

Back to the grinding, I wonder if the people who sharpen them are the same people who grind the blades, as it would seem to me that if you can do primary grinds as clean as I have seen then the edges should be trivial.

It seems that way to me anyway, as I have to be fairly careful not to flatten a point, and find it hard to apply a swedge evenly (even just to tell by eye), but can get an edge closer without much difficulty.

Unless all the primary is jig and the edge freehand.

-Cliff
 
OK, Cliff. Seriously...
I would hazard a guess that if it came out of a makers shop, the same guy did both. If it came from a factory, someone else did it. :)
 
I figured out a simple jig/guide for sharpening my blades to insure consistent edge bevels.. Hell I aint been doing it as long as Kit.. :D
 
It is because the vast majority of people are right handed (that has to do with the majority of bevel discrepencies you have noticed on one side verses another). The predominate hand will always, in most cases, have best control pulling toward itself therefore, the predominate hand will have less control pushing away.

Just a thought based on my own lack of intense enough dexterity.

RL
 
My guess would be that some makers are over sharpening on the strong side because it is easier for them. Then they are sharpening on their weaker side. Once the edges meet, it is counter productive to keep sharpening because the blade will get thicker. So they probably are changing the angle to make the sides look like they match to the average user. When I first started I did this. I would take a few passes on the right side then a few on the left side. But I always seemed to make more on the right side, because the knife was almost done and I didn't want to screw it up at the very last step.(which I have done) Now I take one pass on my right side, then one on the left side. I still have to concentrate on making sure I spend equal time on my week side when sharpening as I do on my strong side. It is just much easier to sharpen with your good hand. It also could be that some makers primary bevels dont meet in the center of the blade, so they are sharpening to compensate for this. I also did this on some very early knives when I was just starting out.
Kyle Fuglesten
 
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