How long will the concave edge stay Sharp compared to a Scandi edge?

[Qsharp]

Hi Guys, I am new to sharpening, therefore I know I have a lot to learn.  I hope my question doesn't sound too silly.

I am considering purchasing the Tormek T-8 But I have a slight concern. Am I right in thinking when sharpening high-end chefs' knives using the T8 one can expect to end up with a small concave edge.

If I am correct, is my customer at a disadvantage in that the razor sharpness will only last for about three months with normal use.

Comparing the Concave to the Scandi edge, I have been told one would expect the sharpness to last for up to 6 months. From my customers point of view, this would be significant.

I would be grateful if you guys could let me have your opinions on how long one can expect the edge to remain razor sharp using the Tormek T8.

[John_B]

Here is a thread where it is discussed.
https://forum.tormek.com/index.php?topic=3840.msg25741#msg25741

I have found that proper usage and knife care have a greater impact on longevity than the minor concave edge. I have seen no data that shows a 2X life for a Scandi edge. I think if this were true butchers and other high use professions would not allow their knives to be sharpened on a Tormek; which does not happen as many have long standing relationships with Tormek sharpeners. Like a myriad of things you hear on the Internet unsubstantiated myths and beliefs tend to have a life of their own. Knife sharpening is no different in this regard.

[Ken S]

Qsharp, you ask an excellent question. By studying the thread that John linked, you will find an excellent answer.

I believe the 3 months vs 6 months is an oversimplification of questionable accuracy. Too many other variables must be considered. However, beginning with hollow grinding: The issue was not new when I purchased my six inch dry grinder in 1973. Back then, almost every home and small business shop had a six inch dry grinder, almost all of them also being 3450rpm "high speed" grinders. Thje hollow grind was quite noticeable, and assisted in sharpening just the front and back of the bevel. This was a substantial reduction in labor.

This reduction in sharpening labor is unnecessary with the Tormek; the motor does the labor. A more important factor in edge retention is deburring and post sharpening edge treatment.

Ken

[cbwx34]

Hi Guys, I am new to sharpening, therefore I know I have a lot to learn.  I hope my question doesn't sound too silly.

I am considering purchasing the Tormek T-8 But I have a slight concern. Am I right in thinking when sharpening high-end chefs' knives using the T8 one can expect to end up with a small concave edge.

If I am correct, is my customer at a disadvantage in that the razor sharpness will only last for about three months with normal use.

Comparing the Concave to the Scandi edge, I have been told one would expect the sharpness to last for up to 6 months. From my customers point of view, this would be significant.

I would be grateful if you guys could let me have your opinions on how long one can expect the edge to remain razor sharp using the Tormek T8.

Just for a bit of context/reference... do you have place or link where this info is coming from?

Add me to the opinion that the 3 month vs. 6 month based on grind type... well I've not seen any actual testing that supports that.  And as stated elsewhere, the hollow on a kitchen knife is almost negligible.

Most knives need some type of regular maintenance to maintain sharpness, and once you learn that, you can maintain a knife at a higher level of sharpness for a greater length of time between actual sharpening sessions.

Since you said "customer", it would be beneficial to teach them a bit of maintenance.  If it's a commercial kitchen, it may be more beneficial for you and them, to increase how often you return.

[Stickan]

I have a story to share, told to me by the main importer of high-end Japanese knives in Sweden.

A father calls and complains about some knifes he bought. For a Christmas present, he purchased two Global G-2 knives and gave one each to his two twin daughters.
At a visit, he found that one knife was very dull and had some chip out in the blade and when he visited the other daughter, her knife was as new, sharp, and in great shape. So obviously there was something wrong with one of them, he thought. He calls the importer and explains the situation and wants a new knife on warranty but during the call, my friend/importer asks about how the knives has been used and how they were cleaned. During this discussion, the father starts to understand that his two daughters use the knives differently and even more so, one daughter had always been taking care of her belongings and kept things in nice shape whilst the other one was always doing things in a hurry and did not take care of her belongings and always broke things. I think we can guess who had the dull knife?

And this is why its hard to say how long a knife will stay sharp. The user determines how long a knife stary sharp. For kitchen knives, the importer I just wrote about, uses Tormek T-8 for service jobs and also T-2 and T-4 when doing demons in stores. A edge last long if you have the correct angle for what its used for. Even if you get a hollow gring on a 2 mm edgeline on a kitchen knife, its imposible to feel any different to an flat scandi grind. Also have in mind that the amount of steel behind a 30 degree hollow grind its the same as on a scandi grind. It's just measured close to the edge and not in the hollow.

Best,
Stig

[Qsharp]

You all blew me away with the detailed responses I received to my question. The information provided was clear, and it clarified the doubts I had about the information a career sharpener gave me.

Cbwx34 - In answer to your question, I had seen a video where a sharpener had turned the wheel horizontal. It immediately struck me he was avoiding the concave edge that comes with sharpening on a wheel. I made contact to ask about his machine and where he got it. Turns out his machine was self-made.

When we corresponded more via email. He provided the following information. This is a copy of his statement... (Most Sharpeners grind concave because you get a high sharpness easily and cheaply.  The disadvantage for the customer is that the sharpness only lasts about 3 months.  That's why I chose the scandy grind.  It is a bit more complex to maintain the sharpness but the customer can min.  6 months + count on the sharpness).

His statement left a doubt in my mind. Hence, posing the question yesterday. I don't want to disclose his name as he was genuinely trying to be helpful by giving me his opinion. But it raised a point that I felt I needed to fully understand.

I sincerely appreciate all the replies as they were all tremendously helpful. I definitely feel that it has clarified the point. Thanks a million to all you guys.

[Ken S]

Qsharp,

One of my favorite Mark Twain quotes fits the Tormek. "Man is the only creature with the one true religion, all seven of them."

Ken

[cbwx34]

...
Cbwx34 - In answer to your question, I had seen a video where a sharpener had turned the wheel horizontal. It immediately struck me he was avoiding the concave edge that comes with sharpening on a wheel. I made contact to ask about his machine and where he got it. Turns out his machine was self-made.

When we corresponded more via email. He provided the following information. This is a copy of his statement... (Most Sharpeners grind concave because you get a high sharpness easily and cheaply.  The disadvantage for the customer is that the sharpness only lasts about 3 months.  That's why I chose the scandy grind.  It is a bit more complex to maintain the sharpness but the customer can min.  6 months + count on the sharpness).

His statement left a doubt in my mind. Hence, posing the question yesterday. I don't want to disclose his name as he was genuinely trying to be helpful by giving me his opinion. But it raised a point that I felt I needed to fully understand.
...

Thanks.  I wasn't interested in the "who" as much as the actual testing done (if any).

Kinda sounds subjective, for example "easily and cheaply" can be done on a belt sander.  I'd also wonder about the edge maintenance, for example, it could be possible that the "more complex" method of maintaining the edge, could also result in it being longer lasting?

Qsharp,

One of my favorite Mark Twain quotes fits the Tormek. "Man is the only creature with the one true religion, all seven of them."

Ken

Perfect summation.

[Ken S]

I agree with CB. I have no problem with the "who"; however, I do have a problem with the lack of reliable published testing. This is certainly not limited to this situation.

Ken

[John_B]

You are right Ken and CB! Trying to source information is very difficult.

The Internet is rife with inaccurate and wrong information on almost any subject you can name. Misinformation spreads site to site unverified and often unquestioned. Seeing it on a site of a well recognized person is no guarantee of factual data. I can not tell you when doing a Google search how often I have seen information copied word for word on different sites without and source references. Sadly you will see this on product review sites as well.

[Ken S]

Sadly, John, I must agree with you. That is why I frequently post links to videos made by sources I respect.
Let's build up the reservoir of good videos.

Ken

[cbwx34]

Sadly, John, I must agree with you. That is why I frequently post links to videos made by sources I respect.
Let's build up the reservoir of good videos.

Ken

You should consider creating a Playlist of your favorite Tormek videos in YouTube...

https://support.google.com/youtube/answer/57792

... then you can share the link to your playlist of your favorite videos (consider adding it to your signature)... all in one place, for easy access.