Help. I just did a small batch of kitchen knives and 8 out of 10 got under 200 Bess. The last 2 knives were sharpened the same way and I couldn't get then Sharp to save my life and I mean to save my life???? Torkek T8 started with 200 grit then 2000 and leather wheel, and they were duller than when I started.???? Is it me, the steel in the blade, just don't know very frustrating. Please help any information would be greatly appreciated.
Quote from: can sharp on April 14, 2022, 12:37:14 AM
Help. I just did a small batch of kitchen knives and 8 out of 10 got under 200 Bess. The last 2 knives were sharpened the same way and I couldn't get then Sharp to save my life and I mean to save my life???? Torkek T8 started with 200 grit then 2000 and leather wheel, and they were duller than when I started.???? Is it me, the steel in the blade, just don't know very frustrating. Please help any information would be greatly appreciated.
Could be a few reasons, but I'm always a "back to basics"... make sure you create a burr on both sides, mark the edge with a Sharpie if needed, to see where metal is being removed, etc.
Sometimes it helps to make a 90° pass on a stone (not necessarily a moving wheel, just a swipe or two with the wheel off)... this removes any bad metal that might be at the edge, then you can form a new edge.
Do you have more information on the troublesome knives (sharpening angle, steel quality, maybe a pic of the edge ) ?
As cbwx34 mentioned, it may be you're sharpening the sides and honing the dull edge...
It may also be a very soft steel, maybe with too acute an angle, and the edge gets rolled when honing.
For me it seems to be the problem of the wire edge burr. Vadim (RIP) explained it in his booklet and on YouTube:
https://youtu.be/KCkvkaeAtM0
https://youtu.be/N9o8E0rSXO4
https://youtu.be/TLfDeE7JRAA
Hope it helps!
Regards
Drilon
When I first started I found that it was easy to negate the work you have done on the stone with improper honing. I remember I would have knives come out great then a few would seem duller than they were after the stone. With a couple of videos and practice I soon acquired the skill to hone properly.
For sharper knives and consistency I have since moved to guided honing using the Front Vertical Base (FVB). This method allows the sharpener to adjust the honing angle base on the properties of the steel the knif is made of.
One of the very few (key words "very few") side benefits of Covid has been Tormek's online classes. I have complained for years about the lack of in depth video training from Sweden. Today we are fortunate enough to have an excellent and expanding library of video training which acknowledges the real world problems of sharpening with any system.
I place high value in what the Tormek instructors teach. What comes to mind in this situation is Wolfgang's comment near the end of the advanced knife sharpening class. Talking about which grinding wheels to use, he says that any steel knife can be sharpened with the SG wheel. He clarifies this statement by adding that it may take longer. Both sharpening and honing may require both more time and a more meticulous technique as well as more experience.
Like many of us, I have also studied the Knife Grinders videos. I particularly like the video where Wootz (Vadim) uses the Tormek grinding wheel, leather honing wheel, and PA-70 honing compound. Wootz adds his extensive experience and meticulous technique. I believe that with a disciplined approach, we can do anything that Wootz did.
Stay with those two difficult knives, one at a time. Set your mind to sharpen one of them rather than sharpening ten knives. Your time will be rewarded.
Ken
I'm not sure what you mean when you say that you got under a 200 Bess.
Quote from: Ken98660 on April 20, 2022, 08:44:50 PM
I'm not sure what you mean when you say that you got under a 200 Bess.
https://www.knivesandtools.co.uk/en/ct/how-does-the-edge-on-up-sharpness-test-work.htm
BESS is a unit defined by the force (weight) you need to cut a special thin polycarbonate filament with your knife. The smaller the BESS value is the sharper is your knife. There is a table showing a comparisons between BESS values and common descriptions:
http://knifegrinders.com.au/Manuals/Sharpness_Chart.pdf
Regards,
Drilon
I have gotten knives like this and have found that the needed more grinding than I originally thought. This is easily seen using a jeweler's loupe. You will often see nicely ground areas, however as you get closer to the apex you will notice that the stone has not even touched it. Many knives are inconsistently sharpened from the factory but more often the owner has used a sharpener that was not compatible with the original sharpening angle. I also came across this when I experimented with changing the angle from say 15° to 12°. It took more grinding to get all the way to the apex.
I concur with John. Heavy convex grinding can also do that, and require a lot of shoulder thinng before getting to the apex.
Thanks for those that posted info on the BESS test - I was wondering myself! ;)
Quote from: Ken S on April 15, 2022, 04:15:38 PM
I place high value in what the Tormek instructors teach. What comes to mind in this situation is Wolfgang's comment near the end of the advanced knife sharpening class. Talking about which grinding wheels to use, he says that any steel knife can be sharpened with the SG wheel. He clarifies this statement by adding that it may take longer. Both sharpening and honing may require both more time and a more meticulous technique as well as more experience.
My understanding, from Wootz and others, is that, while you
can sharpen wear resistant steels with the SG wheel, you sacrifice more than just grinding time. That's because the aluminum oxide abbrasive in the SG wheel isn't as hard as the vanadium carbide in steels like Maxamet, 10v, s100v, k390, etc. As a result, you end up just wearing away the softer steel matrix around the carbides, which eventually tear out of the edge.
In contrast, CBN and diamond will actually cut the vanadium carbides and thus produce a longer lasting edge.
If you're not familiar with it (I'm sure most of you are!), Larrin Thomas' Knife Steel Nerds site is an invaluable resource on steels. Larrin's a PhD metalurgist and the inventor of the new wonder steel: Magnacut.
https://knifesteelnerds.com/2021/10/19/knife-steels-rated-by-a-metallurgist-toughness-edge-retention-and-corrosion-resistance/
Quote from: 3D Anvil on May 02, 2022, 09:55:52 PM
My understanding, from Wootz and others, is that, while you can sharpen wear resistant steels with the SG wheel, you sacrifice more than just grinding time. That's because the aluminum oxide abbrasive in the SG wheel isn't as hard as the vanadium carbide in steels like Maxamet, 10v, s100v, k390, etc. As a result, you end up just wearing away the softer steel matrix around the carbides, which eventually tear out of the edge.
In contrast, CBN and diamond will actually cut the vanadium carbides and thus produce a longer lasting edge.
If you're not familiar with it (I'm sure most of you are!), Larrin Thomas' Knife Steel Nerds site is an invaluable resource on steels. Larrin's a PhD metalurgist and the inventor of the new wonder steel: Magnacut.
https://knifesteelnerds.com/2021/10/19/knife-steels-rated-by-a-metallurgist-toughness-edge-retention-and-corrosion-resistance/
Coarser (more coarse?) abrasion should work... more to read...
https://scienceofsharp.com/category/super-steel/
:)