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 Post subject: PM Steel Traits, Sharpening...
PostPosted: Sun Apr 13, 2014 6:20 pm 

Joined: Fri Apr 11, 2014 11:55 pm
Posts: 5
So I had some fun yesterday. My fiance got us in a pickling class. We did some onions and carrots. Instructor brought 2 10" chef's, um, well, gee, I don't want to insult knives. Let's call them bludgeons. I did half the cutting. More like half the wedging. Cutting the carrot in half with a draw motion would inevitably sent the left half of the carrot shooting several feet away, and usually cracked thru on the bottom 1/3rd. Sheesh.

But it was a chance to play with a longer knife. With a 10" slab I wasn't choking up on it, and I wasn't concerned with the length until I had to start really pushing it around. Pinch grip with a bludgeon and a squared off spine is kind of hard on your index finger. Geez, I never realized how good my 'ok' kitchen knives are! I was struggling a bit with tip control while trying to split the carrots longitudinally, but I attribute that to the fact that both sides of the thing were almost equally as sharp.

Having said that, yesterday's experience, and the experience that everyone is sharing leads me to think I should start with a 240 laser. Get one, use it. If I find that I constantly want a longer blade, then I can get one of those. I suspect I am going to want a longer knife in the 270 category. But it will be interesting to see what I want it for. If everything I want a longer knife for involves bones and really hard veggies like spaghetti squash, then a laser would be the wrong knife anyways.

So, I now have a couple more questions.

First one is in relation to cedarhouse's post. Yes, PM is an interesting tech. I see some that are layered with pretty stainless on the outside. I want to stay away from the layered steels. The materials guy in me just isn't thrilled about sandwich steels. That's the part that is so interested in tool steel. And PM. I know the PMs get very hard. It would seem that the harder a knife gets, the less flexible and therefore more prone to chip it gets. Correct? I am not concerned about sharpening a super hard knife. I am sure that both WE and EP have stones that will, with patience, sharpen the super hard PM steels to a hell of an edge. (Right?) Suggestions??

Second question. I have noticed that all of the Richardson private label knives are designed to be very tall. I thought that this was part of the more french profile and less of a Japanese profile. I now understand that we are talking about the rocker of the edge. But why does Richardson design so many of his knives taller than the Japanese stock knives? What is the advantage?

Thanks all!

<mod note:melampus split thread>


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 Post subject: Re: Richmond HD 270
PostPosted: Sun Apr 13, 2014 6:29 pm 
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Joined: Wed Sep 18, 2013 11:21 pm
Posts: 661
Location: Minneapolis, MN
Slider5150 wrote:Second question. I have noticed that all of the Richardson private label knives are designed to be very tall. I thought that this was part of the more french profile and less of a Japanese profile. I now understand that we are talking about the rocker of the edge. But why does Richardson design so many of his knives taller than the Japanese stock knives? What is the advantage?

Thanks all!


Scooping, when processing large amounts of veg you scoop with the blade and deposit to somewhere else (storage, pot etc..)
Taller blade more scooping power!!


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 Post subject: Re: Richmond HD 270
PostPosted: Mon Apr 14, 2014 1:23 am 

Joined: Thu May 24, 2012 6:20 am
Posts: 1829
Unfortunately I do not have a PM steel knife, so I am no authority. That said, my understanding is most PM steels abrade just fine with high quality stones, ie Choseras, Shaptons, the more aggressive Nubatamas, etc. There are some, M390 is one I have read about, that really are tough to abrade. Unfortunately, I am not really knowledgeable enough to give you any specific recommendations.

As far as chipping is concerned it is my understanding that PM steels will chip as any high hardness steel will, but geometry, quality of manufacture, etc also inform durability. I would guess, and it is only a guess, that reasonably competent knife skills will keep a PM knife perfectly functional for as long as any traditional steel.

I am a little curious why you are concerned about clad construction. Are you just not interested in the damascus cladding, or are you uncomfortable with any cladding? Clad construction is very common on the site. For example, the Konosuke HD, HH, White #2, and honyaki lines are monosteel, but Kono/Addict SLD is clad.

Cladding is used to reduce cost of manufacture, allow a lower alloy, tougher steel to support the harder more brittle core, protect a more reactive core steel, and act as a quick cutting, ablative layer which eases sharpening and thinning.


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 Post subject: Re: Richmond HD 270
PostPosted: Mon Apr 14, 2014 6:18 pm 

Joined: Fri Apr 11, 2014 11:55 pm
Posts: 5
So the materials guy in me doesn't like the layered steel. Doing failure analysis for a living, I am used to finding material failures at material changes/interfaces. Differences in flex, thermal expansion & contration rates etc. It seems to me that the big benefit to cladding is that the manufacturing cost is reduced. Some like Shun then put this savings into making a pretty knife. Others pass along the savings. But it is to save money. I would rather buy a better tool than save a few bucks. I am most likely overly sensitive to the interface between the materials, but it is something that would keep me concerned, so I am pretty set on a monosteel.


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 Post subject: Re: Richmond HD 270
PostPosted: Mon Apr 14, 2014 6:39 pm 

Joined: Thu Apr 03, 2014 12:52 am
Posts: 405
Cladding or San Mai separation should not be a concern unless you use in a brutal way like a machete in the jungle.

I have never seen or heard of layering failure - not enough horizontal sheering in normal kitchen use.


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 Post subject: Re: Richmond HD 270
PostPosted: Mon Apr 14, 2014 7:03 pm 

Joined: Thu May 24, 2012 6:20 am
Posts: 1829
That's cool, just curious. What type of product are you observing material failure in?

FWIW, Murray Carter has specifically referenced the benefits I listed above as desirable characteristics of clad construction.

Because of the ubiquity of clad construction: a) I have learned to stop worrying and love the san-mai, I too had reservations in the past :); b) make sure you inquire about any knife before purchasing. Many knives are not obviously clad so you will want to confirm their construction before making a purchase.


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 Post subject: Re: Richmond HD 270
PostPosted: Mon Apr 14, 2014 7:14 pm 

Joined: Fri Apr 11, 2014 11:55 pm
Posts: 5
I work on failure analysis mostly of polymers and metals. While the failures are mechanical in nature, the causes can be either mechanical or chemical in nature. So I see potential flaws EVERYWHERE.... I am a bit overkill about it because I see so many failure, and in my head, I KNOW i am seeing a very small percentage of most parts, but it is still experience that is hard to overcome.

I know it is common, and have to keep that in mind. I think Damascus is beautiful. I might very well end up with one at some point when my comfort level allows. :)

Thanks for the tip on double checking knives to make sure they are monosteel!


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 Post subject: Re: PM Steel Traits, Sharpening...
PostPosted: Mon Apr 14, 2014 9:07 pm 

Joined: Tue May 29, 2012 12:29 am
Posts: 920
With your line of work you should know that a proper bond is the strongest point of the structure?

When it comes to PM steels I think there is a lot of smoke in the air here. Just because it's a "PM" steel does not mean it's harder or more brittle, it means it's been processed in a different way and is likely a alloy blend that does not smelt properly in a typical furnace. In some cases such as 154cm and CPM-154 it's simply for grain refinement and better alloy distribution. What does that mean to you or me? Absolutely nothing! With like examples you would never know the difference and would think they were the exact same steel.

It's all about alloy content and the percentage of each element. When you know what the elements do at given percentages you can anticipate the performance but just labeling it as "PM" doesn't give you any idea of performance.


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 Post subject: Re: PM Steel Traits, Sharpening...
PostPosted: Tue Apr 15, 2014 5:04 am 

Joined: Fri Apr 11, 2014 11:55 pm
Posts: 5
Good point about the PM.

As for the proper bond. That is, funny enough, the thing for me. I see almost exclusively improper bonds. Crevice corrosion walking up a join like we are talking about. An improper bond creating a torsional shear between one steel and the other. When the mfg gets it right, I don't see it! :) And the mfg does get it right most, no, the vast majority of the time. But my experience still jades me.


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 Post subject: Re: PM Steel Traits, Sharpening...
PostPosted: Tue Apr 15, 2014 11:46 am 

Joined: Wed Feb 20, 2013 2:22 am
Posts: 733
Sliders new knife will probably spend some time undergoing eddy current NDI.


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