How sharp is sharp enough?

[3D Anvil]

Specifically for commercial sharpening, do you guys have an opinion?  What would you consider to be a satisfactory edge from a sharpening service?  Or a superior result?

My thinking is that a BESS score in the 135 range would be a satisfactory result, while something close to 100 would be a superior result.  I believe 135 is sharper than 99% of factory edges, and is actually sharper than 100% of the scores of new knives I've tested, including some costing $500 and up.

I'd like to produce a superior result, but with the caveat that I have to be able to do it reasonably quickly.  I've had my Tormek with SG wheel for 2-3 weeks and I'm making progress.  Scored my personal best this morning, taking a $16, 8" Mercer chef's knife from dull (killed edge on coarse side of stone grader) to 110 BESS in just under 7 minutes.  Procedure was to sharpen on SG stone, deburr on denim loaded with Flitz, and finish on plain leather belt (Work Sharp Ken Onion edition with blade grinder attachment).

The biggest time killer is developing a full burr on the course-graded SG stone.  I'm thinking that adding a 400 or 200 grit CBN wheel on the off side would take this under 5 minutes.  I'd save time grading the stone, develop a burr quicker, and then just flip the USB and finish on the SG stone graded to 1000. 

But I'll stick with the current setup for a few more weeks and see where it takes me.   

[Drilon]

You must get a BESS value under 100 to be sure that you removed the root of the burr. Vadim Kraichuk (RIP) explains this in his booklet "Knife deburring". Diamond or CBN wheels in combination with a felt wheel of the right density are the solution.

Best regards,
Drilon

[3D Anvil]

Yes, I know that it's possible to get below 100 using Vadim's formulas, and sharper is better, of course.  But I don't presently have the same equipment that he's using.  Also, the knife I sharpened was at 15°, not 12° as with most of his demonstrations.  In his recent video using two 1/2 speed grinders, 2 CBN wheels, a paper wheel, and a felt wheel, he took a 12° chef's knife to 80 BESS in under 3 minutes, which is fantastic.

But I think that the difference between, e.g., 110 and 80 is pretty much academic, because the first few cuts on a wood board will take the knife up into the 180-250 range. 

[Ken S]

Adam,

I think this is one of the most useful videos Vadim ever made. He shows what a skilled, careful sharpener can achieve with the standard Tormek equipment. He added a FVB.) A BESS reading of 75 is certainly quite sharp.
Admittedly, he used 12° per side; however, I would expect almost as sharp results at 15°. The constraint may be the quality of the $16 knife.

https://youtu.be/UckPmizllk0

Ken

[cbwx34]

Diamond or CBN wheels in combination with a felt wheel of the right density are the solution.
...

I wouldn't say that this is needed.

...
...deburr on denim loaded with Flitz, and finish on a plain leather belt (Work Sharp Ken Onion edition with blade grinder attachment).
...

My .02, this is what you should change.  I'd use the leather wheel on the Tormek with compound, or put some compound on the leather belt.  I've never seen much improvement with a plain leather belt, even under power (and I have the same sharpener).

And I'd try guided honing (on the Tormek), I think there's some benefit to it over freehand.  (On the KO, you can set the angle per the instructions).

[cbwx34]

Adam,

I think this is one of the most useful videos Vadim ever made. He shows what a skilled, careful sharpener can achieve with the standard Tormek equipment. He added a FVB.) A BESS reading of 75 is certainly quite sharp.

https://youtu.be/UckPmizllk0

Ken

Bingo.  (This came in while I was typing).

[John_B]

I agree with CB on the benefits of guided honing. It not only gives you repeatable results but you are able to hone at a slightly greater angle than you sharpened at. This was also a finding of Vadim's testing for most steels. I do have a second leather wheel with 1µ diamonds that I use on my personal knives.

I have a standard wheel and find that most of my time is spent getting the initial burr on a very dull knife. Here I would like to have the coarse CBN or diamond wheel. I have a limited clientele base so speed is not essential.

[3D Anvil]

The problem with Vadim's video is that it takes about 15 minutes to achieve that amazing BESS reading, even with all his experience and skill.

I haven't had great success with the leather honing wheel, guided or not.  I'm getting just okay results (around 135 BESS).  And of course it requires that you remove the grinding wheel, which takes time (and you have to put it back on for the next knife!). 

Just for fun, I took the same knife I was using down to 12° on the blade grinder and then repeated my sharpening process from before, but adding a +.5° pass with a leather belt loaded with chromox.  Got it from no edge to 85 BESS in a little over 5 minutes.  Main difference, IMO, is that it took less time to apex the 12° edge than the 15° edge.

[3D Anvil]

I've never seen much improvement with a plain leather belt, even under power (and I have the same sharpener).

That's surprising.  I get consistently good results with the leather belt on the KO.  For my own knives I usually use a belt with 1 micron diamond followed by plain leather.

[cbwx34]

I've never seen much improvement with a plain leather belt, even under power (and I have the same sharpener).

That's surprising.  I get consistently good results with the leather belt on the KO.  For my own knives I usually use a belt with 1 micron diamond followed by plain leather.

Probably because of the diamond charged belt.    What do the two look like after use?

It's still a step I would eliminate, since your topic here is reducing time in a commercial sharpening situation.

[brute]

 Remember when you use different 250-200MM wheels (Diamond, CBN, Leather, Felt, Paper) your toolbar has to adjusted, every time you change wheels. People sometime use 4 different grit wheels & 4 different micron applied-leather, felt, wheels. Even if the wheels are 250 & 200MM they are not true. They all have to be measured. This could be very time consuming.       
The most important part is how you use Bess tester. You must move the knife very slow when cutting the line..                                                                                                                                                               As you move the knife very slow , you can watch the numbers increase as the line is cut. If you do not see the numbers increase slowly, you are not using Bess tester correctly.

[Ken S]

Brute,

I read your earlier posts. Are you aware of the convexing possibilities of the new KJ jigs? See this online class:

https://youtu.be/JFHqQg5wZEg

For those who want to invest in that much equipment, and are still concerned with sharpening time, having more than one T8 customs probably makes sense. These knives can easily become very expensive. This may not be a problem for your own knives; however, how many customers would be willing to pay that much for sharpening?

Ken

[3D Anvil]

One of the benefits of the CBN and diamond wheels is that they are 250mm and remain that way for their life.  That's a time saver.

So, if I end up with two CBN wheels and then go straight to leather belts ... there is essentially no adjustment needed other than setting the jig's projection distance.  And of course, an adjustment would be needed if the sharpening angle changes.

In contrast, if you have one Tormek and the SG wheel, you spend a lot of time grading the stone (maybe a minute per knife), and if you use the leather wheel for guided honing, that's a real time waster, as you have to remove the grinding stone, swap the USB around to the front, and set the angle for the honing wheel and then reverse the whole process for the next knife.  But if I went that way I'd get a second USB for the FVB and that would save a lot of time.  Still, it's another minute to take the stone and water trough off and put it back on.

I'm quite familiar with the BESS tester and how it should be used.  I've probably done 500-1000 tests by now.

My current thinking is, 160 grit CBN stone on the honing side, SG wheel graded to 400-500, and the KO grinder for honing.  I think that gets me under 5 minutes per knife with a very good result.  If I need to reprofile or do chip repair, I can use the KO grinder with a 120 grit ceramic belt for that.

[Ken S]

Looking back at our longstanding favorite knife sharpening video by Jeff Farris, Jeff generally used his SG-250 graded fine. He didn't normally use the stone grader for knives. Unless a knife is damaged or very dull, using the stone grader is not necessary.

Yes, the SG will gradually decrease in diameter. The key word is gradually.

You may remove the grinding wheel if you choose to. It is not necessary.

Ken

[3D Anvil]

Oof, I don't know about that.  If a knife is really dull, or the angle is slightly different, it takes a while to get a burr using just the fine-graded stone.  Heck, even the coarse-graded stone can take a long time if you don't put some muscle behind it.