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TOPIC: Any point to addidtional passes once a burr....

Re: Any point to addidtional passes once a burr.... 1 year 9 months ago #8342

  • PhilipPasteur
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I'm posting a video I did using a belt grinder. You may wonder why I'm posting this here. The reason is that it is directly relevant to sharpening on a WE.

Some people feel that sharpening asymmetric edges require having a different angle on each side. NOT so!

When sharpening asymmetric bevels on the WE, you can set the angle on both sides at the same angle and just abrade on one side more than the other. I hope this provokes some interesting discussion.

This is the quote from Ken in the post where he linked his video. The point being, in the context of this discussion is, if you grind one side of a blade more than the other, even at the same angle, you will end up with an asymmetrical set of bevels. This will hold just as true when using the WEPS on a folding knive or the belt grinder on a sword.

If this is acceptable, obviously just don't worry about it. If it is important, one needs to develop a set of techniques to prevent this effect.

Similarly, regardless of reducing or increasing the bevel, if one is not careful and concentrates on pulling a full length large burr only on one side before grinding the other, they will likely end up with asymmetry. The centering of the edge of the edge will change. I had it happen to me personally quite a few times before I changed my tactics. If you want to test this, pull a full stong burr on one side of your blade, count strokes. Go to the other side to pull a burr, count strokes. I think you will discover that you require far fewer strokes on the second side, Take a close look at your bevels.
I would be very interested to hear what you find. What I think you will find, having done this, is that you take less than half the number of strokes to get your burr on the second side, and that you will see a distinct asymmetry

If I am doing a knife for a customer, I don't get the luxury of leaving a sharp knife with unequal bevels until the next time (though I have done this on some of my own knives...). There likely will not be a next time... It makes me be more attentive to not letting it happen at all. I described what works for me, in the least amount of time.

I am sure others have methods that are just as effective. I would love to hear about them too!


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Last Edit: 1 year 9 months ago by PhilipPasteur.
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Re: Any point to addidtional passes once a burr.... 1 year 9 months ago #8344

  • Geocyclist
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Correct me if I am wrong. To reword what Ken was saying:

If you had a "perfect" edge, 15 per side, 50/50 bevel meaning both sides are equal bevels, you could grind away at 1 side and go from 50/50 to 100/0. The final angle would still be 15 on the one side. You would "move" the edge from perfectly centered on the spine all the way over to the far side, i.e. it becomes a single bevel knife.

This is what I did in my last re-profile. I worked 1 side to my target 15 degrees. Then the other side, which formed a burr much, much, much sooner. At that point I probably had a 40/60 edge. I know it wasn't 50/50 by just looking at it. I then had to keep grinding on the 2nd side to get back to 50/50. My first thought was confusion, why did the 2nd side for a burr so fast, if i have a burr doesn't that mean I am at 15 degrees? Yes it does, but forming a burr doesn't mean a 50/50 bevel.

So bottom line I think is forming a burr on 2 sides mean you are at your angle, it does not mean the bevels are equal (50/50), assuming you are going for even bevels.

The other lesson learned for me to inspect my bevels more often, especially in the beginning to make sure things are going as expected. I will also re-shapie as needed for checks. I think if follow Phil's advice and work both sides evenly I should avoid this problem of uneven bevels.
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Re: Any point to addidtional passes once a burr.... 1 year 9 months ago #8360

  • cbwx34
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The tip to work it over time is for personal knives, I know commercial sharpening is different.

I'll start with the answer... work both sides a bit at a time, check your work and adjust accordingly.

Maybe the video is confusing the issue. Yes, you can grind one side more than the other and create an asymmetric grind. But you have to go beyond the point of forming a burr.

But if on a knife that is even to start with, if all you do is grind one side to a lower angle, just to the point where you reach the edge, then switch sides and do the same thing, the bevel will still be symmetric. If it's not, there's another reason for it.... the knife wasn't even to begin with (although it may have appeared so), one side was overworked, the knife wasn't centered properly, the angles weren't set the same, etc. Like I said before, more often it's the knife wasn't symmetric to begin with (this includes it was sharpened at 2 different angles so that it appeared even), so check that first. Assuming the setup is correct, marking both sides with a Sharpie and seeing on both sides where it's removed prior to actually starting the sharpening should tell you. If it starts the same, and ends uneven, then it could be you're overdoing one side (creating too large a burr before switching), or the setup is not right.

If you don't discover the real reason they're asymmetric, it's a problem you'll be constantly having to deal with. And by figuring out the real reason, it will help you adjust your sharpening and regrinds to better deal with the various problems you'll encounter, and/or quickly detect and correct a setup problem, should one occur.
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