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In the Shop => Knife Sharpening => Topic started by: john.jcb on April 22, 2019, 11:41:57 pm

Title: Proper Maintenance of a Knifes Edge
Post by: john.jcb on April 22, 2019, 11:41:57 pm
Having joined the ranks of the FVB converts I must say I think the edges of the knives I have sharpened following the process outlined in Vadim's book are definitely sharper than my free hand honing efforts. I need to visit the drug store and buy some paper for the final test. I only have receipts on hand and by feel I think the knife slides through easier than before. My wife has asked me to wear long sleeved shirts when we go out as there is a lot of hair missing on my arms and it looks like I have a condition.

To my questions; assuming I can now deliver knives that are razor sharp what instructions do I provide my customers to help them maintain the edge for as long as possible?
Should we try and use the steel at the +1.5° to 2° increased angle used when honing? I have a steel that consists of two smooth steel rods connected at one end by an adjustable screw. I can set the angle for each side of the knife very precisely and maintain it by drawing the knife towards me while holding it vertically. Most people have the lightly serrated steels while a few have smooth steel. I do not know anyone with a ceramic rod. Which is best? I give a quick lesson on using the steel but I am guessing most are lucky if the come close half of 45° or 22.5° ± 5° or so.


Is there anything else we should be doing to extend the time between sharpening?

 
 

 
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on April 23, 2019, 12:43:35 am
I tested an acacia cutting board, the cheapest sold in supermarkets, and it is edge-friendly. We have lots of acacia in Australia, but no maple; I can only suppose acacia is as soft a wood as maple.

The common belief is that end-grain boards are better, because the knife edge slices mainly between the ends of the wood fibers, rather than across fibers; but I haven't had a chance to test that with the sharpness tester. The end-grain boards are typically made of hardwood. I will get a thick one when we go shopping, and test on its face (end-grain) and side to compare.

Have you read Larrin's experiments https://knifesteelnerds.com/2019/01/21/does-acidic-food-affect-edge-retention/ (https://knifesteelnerds.com/2019/01/21/does-acidic-food-affect-edge-retention/)
Title: Re: Proper Maintenance of a Knifes Edge
Post by: RichColvin on April 23, 2019, 03:28:43 am
Acacia (AKA, Australian Blackwood — https://www.wood-database.com/australian-blackwood/) has a Janka Hardness of 5,180 N.

Maple has a wide range of types (https://www.wood-database.com/wood-articles/differences-between-hard-maple-and-soft-maple/#hardness), and the Janka Hardness ranges from 3,110 N to 6,450 N.

These Janka numbers seem high, but compared to Lignum Vitae (19,510 N) and Gidgee (18,990 N), they are quite soft. (Of course, Balsa is the softest at 390 N.)

I use the Wood Database (https://www.wood-database.com/) for all my reference information.  It is quite good.

Kind regards,
Rich
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Ken S on April 23, 2019, 12:46:44 pm
John,

You bring up an excellent topic. In the ten years that I have used the Tormek and, more importantly, been active on this forum, I have seen many advances in many aspects of sharpening. Tormek has led the way in some areas. The new SVD-186 gouge jig and DBS-22 drill bit jig have reset the state of the art. The TT-50, especially the 2019 version, has raised our truing expectations. I feel that the present diamond and CBN wheels are positive steps forward in the evolution of sharpening. I hope the knife jigs and stone grader will eventually catch up.

We are also seeing major advances from other sources. Originating with Dutchman's tables, we have seen advances in bevel setting on this forum from all parts of the planet. Wootz' research is bearing fruit, a trend I expect to continue growing.

The area where we have the least control is the time between when the customer picks up the newly sharpened knife and returns for resharpening. We must educate our customers (and ourselves) to develop good habits.The early cooking TV host and writer, James Beard, summed this up very well. He stated that kitchen knives deserve the same care that the best silver receives; they are at least as valuable. I think that comment is a good lead when educating our customers.

Over the years, I have practiced several of your suggestions. They have become habits. I have two veteran wooden cutting boards. One is 12” x 18”. It is a delight to use. The second, by John Boos, is 18” x 24”. It is luxurious to use. I use the smaller board for the very small amount of meat that I cut. I put a quality large cutting board in the same just as valuable category as the best silver. I use my knives and cutting boards every day; I have never used my mother's silver.

Careful hand washing, drying and storing edge up in my wooden block have become so ingrained that I cannot be comfortable until I have done them. I credit Stig for teaching me to store my knives edge up in the block.

I believe the proper use of steels is the weakest link in the sharpening chain. I am definitely still learning with steels. I suspect improper use of steels degrades edges more often than correct use improves them. The nice looking steel with file teeth which came with my Henckel set twenty nine years ago has long ago moved out of my knife block and into storage. I keep it only because the unknowing person who eventually buys my Henckel knives from my estate will want it "because it matches".

I presently use two ceramic steels. The first one was a gift from Steve Bottorff. It is a very useful, well made product from Smoky Mountain Knife Works. It is also very inexpensive. It has built in triangle guides to set a correct bevel.If I had a sharpening business, I would sell them or better yet, give them to good customers with multiple knives. I think they would generate both good will and repeat business.

My second ceramic steel is one I tested for Work Sharp. It has a clever design, with alternating quadrants of smooth surface and fine teeth. The ceramic rotates in the handle. I use only the smooth parts and only with a controlled light touch. It also has triangle guides. It is considerably more expensive, however, in my opinion, fairly priced.

I could be happy with either one.

I have thought about purchasing a smooth butcher's steel. These thoughts have advanced to having it on my Amazon wish list. My inner voices are reluctant, as they are well satisfied with my ceramic steels. I still have much to learn.

Keep educating your customers. A satisfied, knowledgeable customer is your best source of growth.

Ken
Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on April 23, 2019, 04:06:03 pm
Here is a picture I found of the steel I have from Razor Edge. It is called Raz-R Steel. I have had used this for many years.
https://www.razoredgesystems.com/products/steels/product/21-raz-r-steel
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on April 25, 2019, 01:47:26 am
My end-grain vs long-grain test did not reveal any difference.

I used pine blocks.
Knives were Victorinox SWIBO out of the box, the factory edge. I picked knives from the box that scored the same on the sharpness tester.
Initial sharpness was 125-130 BESS in both.

As a load I used the Tormek knife jig SVM-45, which weighs 320 gram, as shown on the photo, and did 100 slices, one knife on the end-grain block, and the other knife long-grain.

After 20 slices, there was no change in sharpness in either knife, the same 125 BESS.
After 100 slices, both knives scored 150-155 BESS.

(http://knifegrinders.com.au/photos/end-grain.JPG)

Honestly, the outcome took me by surprise. I only intended to do a quick test to confirm the end-grain wood is better for the edge, but damn me if it is!
Sharpness was measured twice each time, and the results are repeating.

It is so unexpected, that deserves more systematic experimenting, giving each board 1000 cuts, and can make an interesting article for our Australian Knife Magazine:
end-grain chopping boards versus long-grain,
by wood type i.e. softwood vs hardwood and bamboo, cheap chopping boards versus expensive,
by plastic type: Yoshihiro Hi-Soft vs low-density and high-density budget plastic boards.

The next article is due in 2 months, and when out, I will copy the article to this forum.

By what my sharpness tests have shown so far, the cheap softwood cutting boards sold by supermarkets are edge-friendly, end-grain boards have no advantage for edge holding though may last longer, while bamboo and plastic boards are detrimental to the edge, as are the glass and marble.
.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: van on April 25, 2019, 10:17:51 am
I follow ..... with interest  ::)
Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on April 25, 2019, 03:41:48 pm
Perhaps this will make it into the myths of knife sharpening list.

Vadim, do you have any recommended articles on what steel is best and the proper use?
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Ken S on April 25, 2019, 08:19:46 pm
Another excellent testing procedure, Vadim.

Ken
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on April 26, 2019, 08:12:31 am
Perhaps this will make it into the myths of knife sharpening list.
...

I feel the same John, we are about to bust another myth; moreover so my study must be thorough. I have all sorts of chopping boards coming, the Yoshihiro board will take 2 weeks to arrive, since I could not source it locally.
We need firm facts to advise our customers, so I am double-checking the low-density plastic boards vs hard plastic, and re-checking the bamboo; I see glass cutting boards offered even by the higher-end shops, so will include them for re-test as well.
My mates say if the end-grain proves to be myth, we should shoot a video... overall won't take longer than 3 weeks.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on April 26, 2019, 05:28:47 pm
When I look at most end grain cutting boards I notice that the blocks are arranged in a random fashion more for aesthetics not grain alignment. Making a block where the tree rings align with the knife edge would be very difficult.

Another variable that may impact the results; It seems Western chefs chop most things while Asian chefs seem to do more slicing. The design of the knives seems to support this as well.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Al on April 27, 2019, 06:45:37 am
Another thing with end grain boards is the glue used in them. Some resorcinol and epoxys are harder than others and could affect the edge of the knives although I would imagine this would be minimal. Quarter cut boards have a straighter grain than crown cut but I don’t know if this would have any adverse effects.In cabinetmaking which was my job for the last 40+ years chisel blades always stay sharper for longer when used with the grain rather than across the grain.I also will be following Vadim’s research with interest
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Ken S on April 27, 2019, 02:33:02 pm
Al's post illustrates one of the strengths of this forum. It is easy to fall into the trap that sharpening is (only) about steel and abrasives. None of us has extensive experience in all the related skill sets. I do not have the math and science areas that members like Dutchman, Jan, Herman and others have. I do not have the many years of professional sharpening that members like Steve Bottorff have. I do not have the machinist background like Rick and others have. I do not have the disciplined research that Wootz and others have, nor do I have the extensive wood background that Al has.

Because we share our individual areas of expertise, our group total is greater than the sum of the parts.

Let's all keep up the good work.

Ken
Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on April 27, 2019, 08:11:18 pm
To add to the cutting board posssible myth another thing I have read is that if you can cut the board with your knife it is ok to use it. 
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Ken S on April 27, 2019, 10:45:37 pm
Here is a short video describing end and edge grain cutting boards:

https://youtu.be/Zm2SeTCCa2Q

This is the cutting board I have used for more than twenty years. It was pricey, but is a joy to use.

https://www.kitchensource.com/cutting-boards/jb-ra01.htm

In the video, edge grain boards are described as NFS approved for commercial use. It did not mention whether or not end grain boards were so approved. My guess is that such approval would have been a real bragging point. In my case, home kitchen only, it would not matter.

A large cutting board is a luxury. I also have a 12x18" edge grain board I purchased at a Fisher's Big Wheel store in Green Bay, Wisconsin twenty seven years ago. I believe it is maple. It was inexpensive and has given trooper service.

I commend Vadim for his cutting board research. A good sharpener should also know about cutting boards.

Ken
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 12, 2019, 01:35:28 pm
Our latest research on chopping boards is in the Edge Stability Testing section on our website:
http://knifegrinders.com.au/SET/Chopping_Boards.pdf (http://knifegrinders.com.au/SET/Chopping_Boards.pdf)

Abstract from the research conclusions:

"Of all plastic boards, the most edge-friendly is the ubiquitous high density polypropylene, while the
expensive Yoshihiro Hi-Soft board is nothing to rave about in comparison.
Acacia end-grain chopping board has no advantage over the long-grain in keeping your knife sharp;
while the end-grain bamboo board is definitely bad."
...
Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on May 12, 2019, 04:16:56 pm
Our latest research on chopping boards is in the Edge Stability Testing section on our website:
http://knifegrinders.com.au/SET/Chopping_Boards.pdf (http://knifegrinders.com.au/SET/Chopping_Boards.pdf)

Abstract from the research conclusions:

"Of all plastic boards, the most edge-friendly is the ubiquitous high density polypropylene, while the
expensive Yoshihiro Hi-Soft board is nothing to rave about in comparison.
Acacia end-grain chopping board has no advantage over the long-grain in keeping your knife sharp;
while the end-grain bamboo board is definitely bad."
...

This was a most interesting read and I think definitely myth busting.

As I was looking at the comparison charts I thought you must had transposed the data. I am glad to see that all my boards are good for cutting. I wish a SEM was easily available to look at the differences from before and after. Did you try this using the Victorinox knives after they had been sharpened using the process outlined in your recent "Knife Deburring" book? Do knives that are at or near maximum sharpness dull following the protocol you used?

Another question is raised also; if the knife is getting sharper as shown in the tests why do they get dull cutting relatively soft things like tomatoes, potatoes and meat? I wonder if technique enters into it.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Drilon on May 12, 2019, 07:29:55 pm
Thank you for this comparison. I like data based results! Great.

Drilon

Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 12, 2019, 10:24:57 pm
I have added to the end of the above PDF a page with full experimental data.

Looking at the sharpness numbers, you can see why the high-density polypropylene board comes as the best chopping board - I highlighted it in green in the table.
It was mystical to observe the knife getting sharper and sharper with every next 200 slices on it, how the edge sharpness improved twice and went on near razor sharp between 60 - 70 BESS as I kept cutting.

I am yet to digest these findings.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: van on May 12, 2019, 11:44:46 pm
very interesting study
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 13, 2019, 02:07:02 am
...
This was a most interesting read and I think definitely myth busting.

As I was looking at the comparison charts I thought you must had transposed the data. I am glad to see that all my boards are good for cutting. I wish a SEM was easily available to look at the differences from before and after. Did you try this using the Victorinox knives after they had been sharpened using the process outlined in your recent "Knife Deburring" book? Do knives that are at or near maximum sharpness dull following the protocol you used?

Another question is raised also; if the knife is getting sharper as shown in the tests why do they get dull cutting relatively soft things like tomatoes, potatoes and meat? I wonder if technique enters into it.

New identical knives with factory edge were used for this test on purpose, to rule out other variables and focus on the chopping board material.
Important is that the testing was done with the load within natural cutting forces.

Re-sharpened knives, provided they are cleanly deburred, outlast the factory edge, it is a commonplace.
With these data on hand, we can confidently say that if the knife fails early on an edge-friendly chopping board, it is due to incorrect technique and chiefly due to the edge rolling. 
Knives dull by 2 mechanisms: abrasion and rolling.
In my test knives are perpendicular to the chopping board and if they dull it is due to abrasion.
If the cutter often scrapes the board laterally, or holds the knife out of the vertical, the rolling will prevail.

E.g. the habit of scraping food pieces off the board with the spine of the knife rather than the edge eliminates one cause of rolling.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Drilon on May 13, 2019, 08:31:33 pm
Of course I started immidiately to search for a source of HDPP chopping/cutting boards. But the result was disappointing, I found no supplier for these boards in home kitchen sizes. Any suggestions where to look?
 
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Jan on May 13, 2019, 08:48:13 pm

Another question is raised also; if the knife is getting sharper as shown in the tests why do they get dull cutting relatively soft things like tomatoes, potatoes and meat? I wonder if technique enters into it.

Tormek recommends to cut through the end grain of a block of wood as a deburring method for some blades. In this experiment we possibly also clean/deburr and polish the edge, which results in lowering the BESS sharpness score.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 14, 2019, 05:53:40 am
... In this experiment we possibly also clean/deburr and polish the edge, which results in lowering the BESS sharpness score.

Suppose it is not about the burr, suppose the apex is clean - any other explanations?
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 14, 2019, 08:09:42 am
FACTORY EDGE VS RE-SHARPENED

I re-sharpened the knife used in our chopping board experiment (http://knifegrinders.com.au/SET/Chopping_Boards.pdf) at the same 16 dps, using our sharpening and deburring procedure for mainstream stainless steel knives. The edge angle was controlled with our computer software for Tormek, and verified with a laser protractor.
The only difference was that I started on #80 CBN wheel to remove the metal affected by factory sharpening, and then followed our standard procedure on CBN wheels #200, #400, #1000 and deburred as described on our website http://knifegrinders.com.au/06Procedures_SS.htm (http://knifegrinders.com.au/06Procedures_SS.htm)

The edge scored 80 BESS, so I had to bring it to the initial sharpness of the knives used in the experiment which was 120 BESS - I did it by rounding the apex by gently honing it on the rock-hard felt wheel with 1-micron diamonds on Tormek at 2.5 degree higher than the edge angle, till the edge started scoring the same as the knife in the experiment.

Then I tested the low-density polyethylene board the same way we did with the factory-sharpened knife.
If you ask me why i did not use the best edge-friendly high-density polypropylene board - I avoided extremes on purpose as I wanted to look further into the phenomenon of self-improved sharpness as such.

(http://knifegrinders.com.au/photos/re-sharpened.JPG)

Following are the sharpness data and chart.
We see that the re-sharpened and cleanly deburred edge also gets sharper due to this mystical phenomenon, and sharper than the factory edge.
We see that it is not plastic specific, and not about the burr.
I am still scratching my head for a plausible explanation of this phenomenon.
Comments are welcome.

(http://knifegrinders.com.au/photos/re-sharpened_data.png)

(http://knifegrinders.com.au/photos/chart.png)

Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on May 14, 2019, 01:08:24 pm
Of course I started immidiately to search for a source of HDPP chopping/cutting boards. But the result was disappointing, I found no supplier for these boards in home kitchen sizes. Any suggestions where to look?

Here is one source. Different colors are offered for different food.

https://www.amazon.com/Commercial-Grade-Plastic-Cutting-Board/dp/B01LZNZZX6
Title: Re: Proper Maintenance of a Knifes Edge
Post by: john.jcb on May 14, 2019, 01:29:34 pm
FACTORY EDGE VS RE-SHARPENED

Following are the sharpness data and chart.
We see that the re-sharpened and cleanly deburred edge also gets sharper due to this mystical phenomenon, and sharper than the factory edge.
We see that it is not plastic specific, and not about the burr.
I am still scratching my head for a plausible explanation of this phenomenon.
Comments are welcome.

Is it possible that during the first cuts of the experiment the knife cuts the board forming a 32° V in the material and as you make more cuts this V is acting as a strop on the sharpened edge? Since there is no burr no tearing at the apex would occur as was seen in your other deburring tests. If the knife were moved to a fresh section of the board after each cut I wonder if the data would change?
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Jan on May 14, 2019, 06:51:58 pm
Yes John, I almost agree with you.  :)

In my understanding deburring a knife edge using low speed hard felt wheel impregnated with 1 micron diamond abrasive results in edge surface with roughness cca 0.1 micron. That can be considered a nice, smooth surface, until we realize, that the apex diameter is only some 0.2 or 0.3 micron (for edge with BESS score 100 or 150). Some of the edge surface irregularities may be caused by burr residua which were more firmly attached to the edge and survived the deburring. The experiment shows that repeated movement of the edge in a 32⁰ V groove can remove/smooth some residual edge surface irregularities and lower the BESS score.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Drilon on May 14, 2019, 08:53:31 pm
Of course I started immidiately to search for a source of HDPP chopping/cutting boards. But the result was disappointing, I found no supplier for these boards in home kitchen sizes. Any suggestions where to look?

Here is one source. Different colors are offered for different food.

https://www.amazon.com/Commercial-Grade-Plastic-Cutting-Board/dp/B01LZNZZX6
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Drilon on May 14, 2019, 08:55:59 pm
Of course I started immidiately to search for a source of HDPP chopping/cutting boards. But the result was disappointing, I found no supplier for these boards in home kitchen sizes. Any suggestions where to look?

Here is one source. Different colors are offered for different food.

https://www.amazon.com/Commercial-Grade-Plastic-Cutting-Board/dp/B01LZNZZX6

Thank you, John.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 14, 2019, 11:00:17 pm
Thank you John and Jan.
The way we tested was 20 slicing cuts under 2 kg load in the same line on the board, move the edge to a fresh board surface, do another 20 slices and so on.

Both your explanations are exactly what must be happening - burnishing of the metal off the sides of the edge near the apex inside the tiny grooves, and smoothing off the irregularities as Jan has nicely described.
I will give myself more time to think it over and will add a paragraph to the Conclusions explaining what we see in the experiments.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Dastagg on May 15, 2019, 12:04:59 am
Could it simply be that the cutting board is continuing to remove a micro burr and it would not matter where on the board it is performed each time, that the board is helping to keep that micro board removed each pass? Just wondering.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 15, 2019, 03:15:16 am
Could it simply be that the cutting board is continuing to remove a micro burr and it would not matter where on the board it is performed each time, that the board is helping to keep that micro board removed each pass? Just wondering.

The tiny grooves on the board seem to be important for this effect to develop in full.
The experimental data tell us that the sharpness improvement starts immediately thanks to removal of the microburr and cleaning smudge and residues from sharpening off the edge, but fully develops only after hundreds of cuts, where I believe the microburr-cleaning has played its role, while burnishing at the sides of the apex comes into play and continues, till the sharpness comes to an improved plateau after 1000 - 2000 cuts.
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Dastagg on May 15, 2019, 03:43:22 pm
Thanks for the extra info to explain your science into the topic. I appreciate how much I am learning about this and am only a typical user of cutting blades and just getting into the sharpening science and I have had my Tormek for two years and was mostly for wood turning sharpening. My knives are getting sharper and sharper now thanks to the info here and your book and extra equipment that I purchased to get better. I am now broke in my retirement, but my knives are sharper. lol
Title: Re: Proper Maintenance of a Knifes Edge
Post by: wootz on May 18, 2019, 10:32:42 am
Update: the edge-hostile plastic board has been identified as Low-density Polypropylene - often in the cutting board specs they say just "Polypropylene".

Video: https://youtu.be/_lktWJKFP2k (https://youtu.be/_lktWJKFP2k)
Title: Re: Proper Maintenance of a Knifes Edge
Post by: Ken S on May 19, 2019, 04:26:43 pm
This you tube from Knife Grinders is all thumbs up, must watch.Vadim of Knife Grinders is the rising tide which makes all knives sharper.

Ken