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Blade Alignment (True Vertical)

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  • #38822
    Rich
    Participant
    • Topics: 10
    • Replies: 51

    I made a mistake and found it too late yesterday.  I sharpened my ZT450, obviously with the blade not perfectly vertical in the jaws.  Obvious outcome but part of the learning curve I guess (just wish I could have learned this on a different knife).

    Lesson learned, I went to sharpen a Wustof Classic 8″ chef’s knife and prior to anything else, I tried to ensure that the blade was in correct, true vertical.  I tightened the jaws and put the angle cube on either side of the blade.  The right side was 2.00 deg and the left 0.15 deg.  I loosened and re-tightened with relatively the same result.  I then put foam tape on the jaws and re-tightened.  Results were relatively the same.

    Shouldn’t the angle on either side of the blade, given correct orientation (truly vertical), be identical?  If this was not the case, the angle the blade is sharpened to would be different on from one side to the other.  Correct?

    #38823
    Rich
    Participant
    • Topics: 10
    • Replies: 51

    After posting, I tried the following:

    1. I installed my ZT450 back into the jaws and checked with the angle cube.  I checked the alignment of the knife when it was only tightened at the top screw. The handle was at zero degrees.  After tightening the bottom screw, the handle was at 0.85 degrees.
    2. I installed my 8″ Wustof chefs knife i mentioned earlier, top screw tight only.  Right 1.30 degrees, Left 1.50 degrees. After tightening the bottom screw, Right 2.35 degrees, Left 0.55 degrees.  I then decided to remove and re-install this knife.  After tightening top and bottom this time, Right 2.75 degrees, Left 0.00 degrees.  Holy Crap!  To have the same bevel on either side of the blade, wouldn’t I have to make an adjustment of Right+2.75 deg and Left -2.75 deg.

    What I have figured out is that when the bottom screw is tightened, the blade rotates to the left.  The taller the blade, the worse this problem becomes.  What is the point to making sure your angles are correct with an angle cube?  Yes, the stones are at the angle you specify but the bevel on your blade is not!  This is VERY frustrating to me!  The level of detail I thought I was getting is false.  This explains why my ZT450 looked so off!!

    Has anyone else seen this problem?  Solution? 🙁

    #38824
    MarcH
    Moderator
    • Topics: 67
    • Replies: 2625

    Rich, You are exactly correct in your observation. This is the clamping tilt or cant caused when clamping a Full Flat Ground (FFG) blades in the old style clamp. As you determined, one side of the clamp is fixed, the other side moves out as you tighten the screw. There are various posts in this Forum on correcting this error caused by clamping. In essence you split the summation of the total error between the sides and correct each arm angle individually to correct for it. So 1 arm you add to the desired bevel angle and one arm you subtract from the desired bevel angle. You can attempt to use a shim of sorts to make a physical correction for the clamping error. This is hard to do repeatedly and predictably.

    This clamping error was the impetus for WE designing the Gen 3 Self Centering Clamp. Which is what I wrote about in your other thread where I asked you which model WE you used. There are also some YouTube videos on this subject, “Correcting for Clamping Error on Wicked Edge”. On a good note, I found, the clamping error is consistently the same each time you clamp the same knife in the same position. So I recorded this error in my sharpening log for future reference to set up the knife for future sharpening. The error will still be there whether or not the spine is clamped parallel to the WE.

    Marc
    (MarcH's Rack-Its)

    2 users thanked author for this post.
    #38825
    sksharp
    Participant
    • Topics: 9
    • Replies: 397

    Hey Rich,

    What WEPS do you have? I have heard and I know from using a lansky that when you clamp the knife that the jaws need to be as close to even top and bottom as possible. If the bottom of the clamp is out to much(gaped) it leaves room at the bottom and can allow the back of the blade to move, so the trick is to try to be sure that the top and bottom of the clamp are touching the blade with even pressure. If the knife is clamped evenly then it could be the grind of the knife is uneven or the alignment of the vice is off. Some flat ground knives are not symmetrical on both sides. These are just some things that I can think of.  Also if the bottom of the clamp is narrower than the top it will allow the knife edge to move. Is this the only knife you have had this problem with? You said the wusthof lined up ok? .1 or even .2 deg. isn’t as big of a deal as 2.5 deg. Let us know please.

    #38826
    sksharp
    Participant
    • Topics: 9
    • Replies: 397

    Thanks Marc, I have heard of a clamping problem with the other vice but didn’t under stand the specifics as I to have the gen 3 vice. The lansky had the same type of issue but I never heard a solution. Thanks for clarifying the problem.

    #38827
    Rich
    Participant
    • Topics: 10
    • Replies: 51

    I believe the cant will happen with any blade, FFG or otherwise.  I wish I would have known before my recent purchase, I would have given much consideration to the Gen 3!

    #38833
    MarcH
    Moderator
    • Topics: 67
    • Replies: 2625

    I believe the cant will happen with any blade, FFG or otherwise.

    Yes, I believe you’re correct.

    Marc
    (MarcH's Rack-Its)

    #38836
    wickededge
    Keymaster
    • Topics: 123
    • Replies: 2936

    I believe the cant will happen with any blade, FFG or otherwise. I wish I would have known before my recent purchase, I would have given much consideration to the Gen 3!

    Rich,

    You might try adding more tape/foam to the insides of the jaws. With large tapers to the blade, you need a little more foam. I get the best results from Moleskin. Another trick is to adjust the space of the jaws, top and bottom so they’re parallel, to the thickness of the spine. Then lightly snug the top and then tighten the bottom. With enough tape/foam/moleskin in place, you should be able to get the jaws vertical. It sounds complicated to do, but once you’re used to it, it’s actually pretty easy.

    -Clay

    1 user thanked author for this post.
    #38844
    tcmeyer
    Participant
    • Topics: 38
    • Replies: 2078

    Rich:  I went another direction and decided to take the angles into account with a fixed setting.  I laid the left face of the blade against the vertical face of the left jaw, then cranked the lower screw to rotate the right jaw until it laid flat against the right side of the blade.  If you’ve measured the angular displacement between the two faces of the blade, you can adjust for it with your angle.  For example, my Delica 4 has about 3.5 degrees between its two faces.  Knowing that the left face is held vertical, we know that the blade is leaning 1.75 degrees to the left, so I deduct 1.75 degrees from the left rod and add 1.75 to the right.  It may be more than you want to deal with, but it works.

    2 users thanked author for this post.
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