EdgePro - Use It Correctly

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heirkb said:
So based on the picture Dave posted, it seems that one side is just sharpened more than the other. Is that right? That's what I meant when I said number of strokes. I should have said material removed (at the same angle).
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No that's exactly correct. Each side should be sharpened as it needs to be. Inevitably you will almost always spend more time (on a right handed knife) working on the right side however just stating this as a rule doesn't help you to look at what you're doing and adjust. Also, each side can have different angles used.
 
I could be way off base here, but I thought early in this thread it was suggested that knifemakers intentionally grind knives with a built-in asymmetry--70/30, 80/20, 60/40, etc.

I'm having trouble understanding this. I've seen many, many videos of knifemakers grinding double-bevel blades. In stock removal, the maker might start with a 10" bar of steel, 1/4" wide. The knifemaker will usually draw a line down the length of the steel bar with a magic marker, then grind each side of the bar until it just reaches the line. In every case I've seen, the line is drawn in the *exact* center of the bar--that is, there's 1/8" on either side of the line, so the edge will end up centered over the spine. I've never seen or heard of a knifemaker saying "Well, I'm going to draw this line 4/64" (or whatever) off-center so I'll end up with a 70/30 blade." If you're starting off with 1/8" stock, that would be well-nigh impossible to do anyway.

Remember I'm just talking about double-bevel knives; single bevels are a whole 'nother category. Also, I have no idea how a forged knife could be purposely hammered to be asymmetic. It seems to me that knifemakers try *real* hard to have the edge perfectly centered over the spine.

I tried the engineer's square trick on a couple dozen Jaanese, French, German, and American double-bevel knives. If those blades are asymmetric, it's way beyond my ability to detect it. And I've probably seen 150 photos on knife forums sighting down the blade from the choil with the edge pointing up, and they all looked perfectly symmetrical to me.

To be fair, I haven't seen one-tenth as many blades as some on this forum. So if anyone has any photos of asymmetric blades, I'd really be interested in seeing them. Also good would be links to articles/videos/etc. where a knifemaker talks about grinding asymmetrically.
 
I've just spent several hours making a drawing and collecting pictures for this thread but as a new member I'm not able to upload... :eek2:
 
Nah, I feel like my computer gets infested with spam and viruses every time I get near sites like that. Paranoia !!! I'll earn my right here instead hehe.

I was going to think out loud regarding assymetry and angles but perhaps I can ask a question instead... Changing the angle every time you flip the blade over is too "labour intensive" to be done in practice. So, how do you work your way around this?

Somehow put in a spacer every time you flip the blade?
I read about one guy using a drill stop collar. How?
Other?
 
Changing the angle every time you flip the blade may be too labor intensive, but that is the cost of using a jig. It takes me about 10 seconds from "I'm gonna sharpen my knife" to rubbing steel on stones. Just setting a jig up sounds too labor intensive to me.

The point he was making was that Japanese knives are made this way and intended to be sharpened by hand, and not with an Edge Pro in mind. You have to adapt how you use the EP to fit the blade, because they aren't going to make knives that are jig-ready in Japan.
 
Is anyone really making jig ready knives anyway :laugh:

Without trying to stir up controversy here, when I saw the title of the thread I half expected to see it as a paper weight or propping something up; However I do agree with Eamon that just setting up a jig sounds too labor intensive, and that if you're using one and have to constantly make that adjust that is the price you pay to do something right and well.
 
I understand that most people here prefer to freehand sharpen, and with good reason. However, I would be interested in heering how people get around the problems here with the Edge pro, I doubt many change their angle so often. If there is little interest I'll take that discussion to another forum though and continue with the blade geometry topic here instead!
 
Hi Dave Martell and everyone. I needed to double check some Japanese kitchen knife asymetrical ideas.

1. The edge is still in the center of the spine or is it to the left side?

2. The right side on a right handed knife has more convexity to allow better food release?

3. The left side is still convex but has a flatter profile since food release is less important?

4. If you say the edge is 70/30 this means you take the total inclusive edge and multiply the right side by .7 and left side by .3 (example 22degree inclusive x .7 = 15.4 and 22degree x .3 = 6.6.)?

Thanks Dave and any others that would like to take a stab at this.

David
 
It's perfectly normal to see an off-centered edge and nobody should care if it's in accordance with the geometry. About the purpose of convexity, that's rather a philosofical question. But one of the effects is indeed easing food release. Two flat blade sides would steer. Note that with European knives it's common to see the left one to be convex, with an almost flat right one. The proportion indicates how much is abraded, not an angle proportion. With both angles being equal it would indicate the bevel height. With your proposed 22 degree inclusive, 9 degree right and 13 left sound more reasonable to me. Regards. Bernard
 
Thanks Benuser, so the right side would have the steeper angle and the left side the more obtuse angle in your 60/40 grind for a right handed knife. 13 & 9. That's interesting about steering. Is there a good fruit or vegetable or roast to test steering of a knife? I have heard single edge knifes tend to steer also.
 
I have to correct. I've said steering, I meant wedging. Steering is IMHO no problem if you turn the knife a few degrees clockwise. I apologise, language problem.
 
I understand, thanks Benuser. What edges do the rest of you like for Gyuto?
 
David Metzger said:
I understand, thanks Benuser. What edges do the rest of you like for Gyuto?
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If 23 degree inclusive was meant for a gyuto, I would certainly suggest a serious micro-bevel, depending on the steel. E.g. stropping on 12/15 degree. But first thinning behind the edge, at the right side, at least. What knife are we talking about?
 
I have about 12 I am making right now, they vary from a true gyuto inspired by Masamoto, a chef style shape inspired by Kramer and a Funayuki inspired by Carter. (along with 50 non kitchen knives) they are almost ready for heat treat (send away to Peters). I tend to work in fairly large batches. The steel is O-1, RC 62 planned for kitchen knives.

So, if I understand you correctly, you are saying the 23 degree inclusive may not hold up to the abuse and micro bevel it to 27 inclusive through stropping? I have noticed that some stats of gyutos have been so thin 1 cm above the edge that the geometry could not be a true convex from the edge. I guess this is where the thinning above the right edge comes into effect.

Thanks for your help, sorry I got off the original posters topic, but it started with the confusion of whether the edge is centered making the EdgePro not work so well or if its the asymetrical grind.

David
 
You don't want to microbevel with a loaded strop, because strops typically have give to them(the only thing that differentiates a strop from a normal abrasive hone), and can/will round the edge. If it isn't loaded, you could roll the edge, remove a burr, or do nothing, depending.

A microbevel is best put on a knife on a medium-to-high grit stone, 4K+.



*edit* also, super thin knives CAN have a true convex from the edge, but this is a lot harder to manage without overgrinding the blade, and has a much lesser impact on the performance of the knife. The reality/efficacy of this exact thing is the subject of ongoing debate.
 
I sometimes use a loaded strop to intentionally add a micro-convex end to a very thin "V" bevel thus making a compound/hybrid edge.

This takes some finesse and practice to learn the correct angle and pressure as it's easy to roll and blunt the edge.
However, I if done right, this can add some strength and durability without sacrificing much performance.
 
Seems like that would not categorically be different than just stropping.


Btw, I'm enjoying the heck out of this thread. there hasn't been a sharpening thread like this in a long time.
 
johndoughy said:
Seems like that would not categorically be different than just stropping.
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It's under the same genus, but a different species from "just stropping. "
When I "just strop" my goal is to just gently brush and polish the bevel... I want the strop to give it a light peck on the lips.
So I use very light pressure and a low angle. I know that, on a microscopic level, this is going to convex the edge, but I want to limit that as much as possible.

However, I when I'm trying to intentionally micro- convex I want the strop to embrace the edge a bit more firmly and just start to wrap around it.
So I'll use more pressure and possibly a different angle. Depending on the strop and angle, I may even look to see a slight depression trailing the edge. To expedited the process and prevent over polishing, I often use lower grit (like 2micron) or even worn 2k w/d sandpaper over the leather or felt.


johndoughy said:
Btw, I'm enjoying the heck out of this thread. there hasn't been a sharpening thread like this in a long time.
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Me too! I don't normally geek out this much when I'm sharpening, but this thread really highlights some of the lesser-known beautiful and subtle intricacies that make kitchen knives so cool.
 
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