Can you add another common misconception to this list please?
I will only be happy to expand on every point in the list, but ATM we are just brainstorming, throwing in ideas.

Myth - Obtuse edge angle has longer edge retention.
Myth - Too fine an edge dulls quicker.
Myth - Convex aids durability of a sharp edge.
Myth - Chopping and batoning requires 40+ degrees edge.
Myth - Super steels hold super-sharp edge.
Myth - 40 degrees for chopping, 30 for cutting, 20 for slicing.
Myth - Certain sharpness for cutting task.
Myth - Manufacturers put an edge angle best for their steel.
Myth - Manufacturers know what edge angle is on their knives
Myth - Manufacturers of quality knives sharpen them right.
Myth - Abrasive grit correlates with the edge sharpness you get.
Myth - Cheap knives are easier to sharpen.
Myth - Surgical steel is of high quality.
Myth - Straight razors are made of high carbon hard steel.
Myth - 12% chromium makes steel stainless.
Myth - Stainless means pitting resistant.
Myth - Any knife can be sharpened to razor sharp.

KS was a famues blacksmith around the year 1500 in Innstrbruk, Austria.

He is mostly famues for his armour and especially his helmets. Along steel quality nerds he is famues for his steel quality and special hardening - never seen after him before 1950.

Search on his name and read about him and his blank weapons and armour if you are interested

Thomas

Here is a link to a fascinating PBS Nova program on the Viking sword.

Enjoy!

https://www.pbs.org/video/nova-secrets-viking-sword/

Ken

http://knifesteelnerds.com/2018/06/18/ma...retention/


Thomas

Here's a question for KG and anyone else who might want to kick in. I watched a video recently of this product being used in a meat processing facility.


Is this the sort of edge straightening tool used in Australian plants KG? This one happens to be made by ERGO. If you're familiar with this or similar tools would be interested in hearing what you know.

You can tell that's its Summer. No crossing guards at the elementary school in the morning and the grass always looks like it needs to mown now. You can also tell by the decreased traffic on the BESS Exchange. People have been cooped up all winter sharpening knives and now it's time to head outdoors where you can use them. We'll keep the home fires burning here until the leaves start falling so everyone have a good and safe Summer!

Earlier this week I had a minor heart attack. I give high marks to all of the capable and friendly people who cared for me.

My one regret is that I was not carrying a hair popping sharp pocket knife with me. The most painful part was when all the adhesive contact tapes for the monitoring were pulled off. I wish I had shaved all my chest and arm hair. 

A more practical solution would have been for the medical staff to have offered to shave it early in the procedures.

Ken

ps All is well. I was given a clean bill of health.

I recently finished my first spool of media for my fabulous new PT50. Congratulations EOU, the PT50 is really a lot faster and easier to use than the original KN100! 

I had a couple small issues with the PT50A. I don't know how the PT50B is different, so this may or may not be applicable.

I don't always have a pair of reading glasses around when I need them, so I was having a little difficulty with a couple things. 

First, it wasn't easy for me to always get the edge of the blade in the slot of the blade rest. Sometimes I would drag the edge across the hard plastic, which probably doesn't make any difference to a 150 edge, but I've been working with fine edges lately. The rest also seemed a little tall, so I decided to customize one of the two knife rests that were included.

I took the magnet off so I could accurately cut the height down to the bottom of the groove, and super glued a wafer of cork on top, which can't affect even a super fine edge. Not having to hit the slot just makes things way easier for me. 

  
It wasn't always easy for me to get the media under the plastic nut on the yolk because of the groove machined into the yolk. I just thought it would be easier if I didn't have to back the plastic nut out of the groove, so I ground the groove off flush.




A couple things- It was easy to grind the groove off perfectly with the bottom of the yolk on the table of a grinder, but I wanted the extra traction of the scratch pattern being horizontal instead of vertical. This was a little trickier, because I had to lay the yolk on it's side, which is round, and eyeball it. I'm not sure how much difference that makes, but I barely need to snug the lock screw, so it seems to work considerably easier to me.

*Special Note* If you grind the groove off the yolk, do not forget to blow the screw hole out with compressed air! There will be metal filings in the hole, which will ruin the plastic threads. Also, the edges of the top groove will be sharp after grinding, so make sure to ease them with fine sandpaper or a buffer.

Just my 2¢.  YMMV

We are lucky that the meat plant has allowed to publish part of our research we did for them.
Meat plants are secretive about everything that gives them a competitive advantage, and as soon as they realize benefits of BESS sharpness testers, they become reluctant to share, especially about the savings.

The article published in the Australian Meat News has about 1/4 of our findings, due to the magazine format and restrictions imposed by the meat company.

The company runs 2 meat plants, an abattoir and training in meat processing, website www.becampbell.com.au

The meat plant in Sydney, Australia processes 2300-2500 pigs a day, from the carcass to ready retail products, portioned and packed.
Knives are used in 3 operations:
- boning;
- dividing cuts; and
- portioning slicing.
This research was on boning knives.

PDF spread >>

In the below chart we've put together SET-tested steels which composition we know.
SET Results are sorted from the best to the worst.

Even without fancy graphs, just looking at the numbers, it is clear that edge retention correlates primarily with the content of wear-resistant alloys, then with the carbon content, and finally with the HRC.



However, when we look at the resistance to initial rolling in the first 5 impact cycles, we see that, though wear-resistant steels do withstand rolling by about 30% better, there is no correlation between the wear resistance and resilience to initial rolling.



The high-vanadium edge sharpness quickly moves beyond the shaving range to just sharp. In the first impacts a 10% vanadium edge apex rolls to the same extent as a 3%, and both the 3% and 10% vanadium edges lose their initial keenness almost at the same rate as a mainstream knife. Considering that the impact assembly weighs just 150 grams, isn't that astonishing?
Higher wear-resistant blades win as stayers, but are equal sprinters.
As one of our readers has commented: "Which may explain why s110v loses it's keenness rather quickly but is able to keep a working edge for a long time"

To make things worse, you cannot steel "supersteels" back to shaving sharp as you can with softer steels – they are too hard for this, and the bent apex stays there as a tiny scraper.
For this reason, professional meat cutters prefer mainstream steel for their knives, as a meat plant veteran commented: "When working in the boning rooms as a boner, after sharpening my knife it needed to shave after steeling for necessary sharpness to work with. Steeling is necessary to get through the day."

It is getting really intriguing what Mike's SET testing of the A2 steel hardened to a range of HRCs will show.
The main lesson we've learnt so far is not to assume anything, yet I wonder if the A2 data will show similar pattern of equal initial keenness loss, but better long-run retention with the increase in HRC or not.
A2 is a high carbon and primarily Molybdenum steel, and if the pattern is different, it will tell us that what we've seen is vanadium-specific and shouldn't be generalized to other wear-resistant alloys.