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I got lots of chips and they ain't potatoes.

Recent Forums Main Forum Knife Specific Discussion I got lots of chips and they ain't potatoes.

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  • #45329
    tcmeyer
    Participant
    • Topics: 37
    • Replies: 1955

    A couple of weeks ago, when I sensed a drop-off in perceived sharpness, I decided to take my Aritsugu chef’s knife out of service for a routine touch-up on my WEPS.  I was shocked to see the amount of damage the edge had accumulated in the relatively light duty work it had been used for in the last years of so.  I’m guessing the edge was hardened, but not tempered. The chips look to be about .010 deep, but I’ll have to check the calibration to be sure.

    My sister’s knife (an exact twin) had delivered a year’s worth of normal use with only one chip near the heel. All other wear was as you’d expect for a knife with a very acute edge angle of about 6 dps.

    I think that if you watch the video, you’ll see that the edge between chips if still quite sharp. However, there ain’t a lot of that edge left. The chips run all the way from heel to tip.

    Has anybody here experienced chips created by cutting hard-crusted bread? Is it possible?

    See the video here.

    #45331
    Organic
    Participant
    • Topics: 17
    • Replies: 929

    This is the knife with the 6 degree per side bevel, right? Knives with high hardness steels and thin edge geometries are prone to chipping. I have chipped my gyuto by accidentally lightly tapping the edge against a plastic bowl. It is not inconceivable that cutting a really robust hunk of bread could do that to a delicate edge.

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    #45332
    tcmeyer
    Participant
    • Topics: 37
    • Replies: 1955

    This is the knife with the 6 degree per side bevel, right? Knives with high hardness steels and thin edge geometries are prone to chipping. I have chipped my gyuto by accidentally lightly tapping the edge against a plastic bowl. It is not inconceivable that cutting a really robust hunk of bread could do that to a delicate edge.

    Yup, I’m coming to that conclusion. I think it’s a combination of the hard crust and the hardness of the board.  The board is one of those thin sheets of a pressed hardboard, kind of like what we used to call masonite.  The problem is probably the amount of force I apply as I try to cut through the bottom crust.  Also, in making that final cut, the entire length of the blade is used.  I’m going to switch to a much softer cutting board, maybe an end-grain checkerboard pattern from maple and walnut.  I’ve got a drawer full of the black walnut pieces, given to me by someone I’d made a knife for long ago.

    In repairing the damage to the Aritsugu, I filed the edge flat, removing the deepest chip recesses.  I then changed the angle to 10.5 degrees and proceeded with the WEPS, starting at 200 and working my way up to 1500, then followed a progression of diamond films (6, 3, 1.5, 1.0 microns).  I ended the job with a new set of cow leather strops, loaded with 1.0 micron paste.  I’m sure that the 21 degree inclusive (10.5 dps) edge is somewhat less sharp than the original 12 degree inclusive (6 dps).  I checked on a piece of telephone book paper and it passed with flying colors.  Really, really, really sharp!  What was also remarkable is that even with the need to reestablish the bevels, it took less than 45 minutes.

    I worked the 200 grit only until the flat was quite narrow, maybe 0.25 mm.  After that, I took each grit in sequence, applying at least 60 strokes per grit.

    • This reply was modified 2 years, 7 months ago by tcmeyer.
    #45334
    MarcH
    Moderator
    • Topics: 61
    • Replies: 2169

    Hey Tom, in my experience, knives specified to cut bread have always been a serrated knife.  That knife is incredibly thin edged.  After a year of use that really didn’t appear unreasonable or an excessive amount of wear.  From what you wrote and I read I was expecting much more pronounced chips and rolling.  Under 50X it really wasn’t horrible.  I can’t tell from the video just how thin the knife blade is but it appears to be very thin, thinner than your average chef’s knife.  I’m sure you’ll be pleased with your wider angle.  I would designate that knife for soft foods like fish or raw boneless meat and not hard crusty bread.  I think that knife is mean to use as a drawing slice like a sushi knife not for push cutting hard foods. JMO

    Marc
    (MarcH's Rack-Its)

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    #45335
    Organic
    Participant
    • Topics: 17
    • Replies: 929

    I purchased this end grain cutting board made by Jones Cutting Boards LLC:

    I have noticed a big boost in edge retention on my knives as a result. I still use polycarbonate boards for poultry prep, but just about everything else is done on that end grain board now.

    4 users thanked author for this post.
    #45343
    tcmeyer
    Participant
    • Topics: 37
    • Replies: 1955

    That’s an absolutely beautiful cutting board.  Is it the sapele hardwood and African mahogany?  Whoowee!   I have a lot of rough-sawn maple laying around.  I was thinking about inlaying some bits of walnut to add a bit of character and contrast.

    #45344
    Readheads
    Participant
    • Topics: 27
    • Replies: 291

    Did you attempt to redo the edge on the entire (1/2 inch) primary bevel or just do a secondary bevel ?  I got an Aritsugu Deba last year and thought it would be nice to establish a WEPS profile on the entire primary but found it pretty much impossible without doing a massive amount of WEPS work. Finding a mount position to get close enough to the “human” made primary turned into a lesson in futility. Yet, these knives are are made to have a single 1/2 inch wide bevel all the way to the apex. I set the Deba aside for now, maybe I will revisit — WDYT ?

    #45345
    tcmeyer
    Participant
    • Topics: 37
    • Replies: 1955

    Thanks for the reply Read…  As you observed, trying to maintain the original bevel width would mean removing a lot of steel.  The wide bevel isn’t actually a true, flat bevel.  It’s more of a convex.  In any case, using the Low Angle Adapter would only get me down to about eight degrees, which is what I put on my sister’s knife.  I decided that the very low angle was too fragile for my purposes, so I went up to 10.5 dps.  When I posted my original video of the factory’s edge, one of the members here responded that the knife didn’t belong in a kitchen.  I had my doubts too, and had limited its use to tomatoes and such.  When it became clear that my sister was using hers regularly, I started using mine on bread as well.  Why?  Because it cut bread better than any knife (serrated or otherwise) I had ever used.

    Even a two-dps increase reduced the bevel width to no more than one millimeter.  I’ll try to take a couple of micro-photos showing bevel width.

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    #45346
    Organic
    Participant
    • Topics: 17
    • Replies: 929

    The board is made of cherry in the 18 x 12 x 1.5 size. I purchased it from an authorized third party retailer (www.houzz.com) because it was a great deal ($94) and it was made by a reputable shop in the US. I actually wanted a walnut board because I thought I preferred the way they look but was pleasantly surprised about how lovely the cherry board was when it arrived. I hope to get another one at some point down the line.

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    #45350
    sksharp
    Participant
    • Topics: 9
    • Replies: 397

    Hard steel chips and soft steel rolls. I’ve had a lot better luck sharpening the softer steels at more acute angles than I’ve had with the harder steels. I have had knife edges fall apart on me and by widening the angle it took care of the problem. My experience has been that the harder steels retain there edge better as long as they are not sharpened at to low of an angle, then they chip, break or just fall apart.

    If that knife you have didn’t get tempered it could explain the chipping with such light use I presume but that is a crazy angle even at 10.5 deg. per side. I’ve had a few carbon knives that would maybe hold an angle that acute but certainly would not hold up to much abuse.

    Thanks for the tip on the board Organic.

    #45376
    tcmeyer
    Participant
    • Topics: 37
    • Replies: 1955

    This discussion has accomplished – I think – what I set out to do, which was to find the cause or theorize around the chip damage.  I’ve come to conclude that I had simply applied too much force to the blade edge as it came in contact with the cutting board(s).  Even with such a sharp knife, cutting through the hard base crust of this bread took quite a bit of force.

    My professional work exposed me to two types of cutting: slicing and bursting.  Burst cutting is typical with thick substrates and is accomplished by displacing the material at the contact point.  The edge actually compresses the material at the cut point before it “bursts” through.  On disposable absorbents production machines, we cut the fibrous paper pulp and the compression provided by the cut operation served to “crimp” the material into discrete segments.  We typically used a tool steel blade which was rectangular in cross section – about 2.5mm thick by about 40mm wide.  The blade was clamped on a parent roll and allowed to flex as it when through the cutting part of its rotation.  To be clear, the long dimension of the blade is cross-ways, relative to the cut.  For thick materials like absorbent fluff, you’d actually hear the crack of the edge finally bursting through the material and hitting the anvil roll.

    In my case here, I was doing something similar by applying pressure to the blade to get it to break through the bottom crust of the bread loaf.  When it finally broke through, the edge would hit the board hard enough to fracture the very thin edge.

    Thanks, Guys…

    • This reply was modified 2 years, 7 months ago by tcmeyer.
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    #45393
    sksharp
    Participant
    • Topics: 9
    • Replies: 397

    Thanks TC, great explanation! This really brings “purpose sharpening” for knives into a clearer view. Not only from a sharpening aspect, but from the cutting side of it as well. It’s important to use knives that are sharpened for a “purpose” for that purpose. For those I sharpen for I do my best to explain what each knife was sharpened to be capable of and in the case of kitchen knives that have at least 3 or 4 knives there should be one capable for anything faced in the kitchen. Knowing which knife to use in which circumstance makes edge retention a lot less of an issue for most knives at least from my own experience.

     

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