Grind Direction

[EOU]

Here's one that we have wondered about for some time; we wonder if it makes a difference, and how much, the direction of the grind. First, should the direction of the grind be consistent throughout the process and second, this sharpening scenario;

Let's say that we have a nice 440C stainless knife and we want to put a micro-bevel on the edge. Let's say that we are using some sort of fine flat stone for this purpose. Does the motion of the knife, relative to the stone, or the stone relative to the knife, such as depicted in, A, B and C make a difference assuming that we are wanting to achieve as thin an apex as possible? 

This may not be able to be answered definitively but we would be interested in your opinions and experiences in the matter. 

   

[Jan]

EOU, in my understanding grinding direction may have substantial influence on the edge because the burr formation is different.

On Tormek grinder you can use both directions without any danger though grinding towards the edge is more frequently used because it is more aggressive and therefor quicker.

I have asked sharpening teacher Steve Bottorff why he prefers grinding away from the edge on Tormek and he told me that is because we get a larger burr, which can be detected sooner, assuming we will check it often during sharpening.

I have prepared a special flat platform which guarantees the same bevel angle for sharpening in both directions.

       

Jan

[Ken S]

EOU, excellent topic!

Jan, I have read many outstanding posts and ideas from you. This one stands out for originality and cleverness! Kudos.

Ken

[EOU]

Thanks Jan. We have some kind of handle on B and C. We're really more curious about A. Anybody had any experience with this grinding technique? Seems to work well enough in the movies. A rock, a short sword or a long knife and a campfire.

[Jan]

Jan, I have read many outstanding posts and ideas from you. This one stands out for originality and cleverness! Kudos.

Ken

Mr. Ken, thanks for your compliment!


Jan

[EOU]

Looked at Ken's post Jan and then had to go back and see what he was talking about due to our lack of familiarity with the Tormek. We've figured it out now and have also deciphered the source of the original problem.  Your work is too good. We're used to looking at modifications that include things like paper clips, angle iron and globs of weld. We can't tell where Tormek's work stops and your's begins. Could you please booger things up a little in the future so that we can see more easily what you've done? Other than that one complaint, very nicely done.

[Jan]

EOU, sorry for skipping any introduction to Tormek.

Tormek grinders are Swedish water cooled machines for sharpening edge tools. It is quite expensive, but high quality standard grinder. Each tool has its own grinding jig which operates on the so called universal support bar. This guarantees consistent sharpening angle.

The knife jig can operate in both grinding directions, towards the edge and away from the edge. Grinding towards the edge is more frequently used because it is more aggressive and therefore quicker. Grinding away from the edge gives larger burr which can be detected sooner, assuming we check it often during sharpening.

       

To avoid mounting the knife into the knife jig some Tormekers developed platforms for free hand sharpening. In the attached picture you can see my homemade flat platform which guarantees the same bevel angle for sharpening in both directions. The smaller flat platform serves for honing.

   

Jan

[EOU]

That helps and thank you Jan. Your modifications were actually much more extensive than we imagined. Well done from both the standpoint of added functionality and craftsmanship.

[Jan]

EOU, thanks for your recognition, appreciated.

Jan

[Bud]

You know EOU that if you think about it most of the ceramic rod sharpeners available are going down (along) the edge. I'm sure those things must work for most people but the one I have doesn't work good for me. I can't even get close to the kind of numbers I get with the Kally. I think Jan is right from my experience, if you want a smaller burr then go into the edge. I've just gotten lazy with this new Kally of mine. Everything I sharpen now is away from the edge and I couldn't be happier with my edges. I must watch the same movies as you do. Just saw one the other night where the bad guy was sharpening down the edge with something that looked like half a brick. Looked like he was going from between 15 and 45 degrees every swipe he made.  Might have been some kind of special bad guy grind.