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Challenges of low blade height

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This topic contains 6 replies, has 6 voices, and was last updated by  Lay 10/03/2019 at 5:13 am.

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  • #52252

    DaveG
    Participant
    • Topics: 4
    • Replies: 6

    First… the question… Will the LAA help in this scenario?

    I am helping a relative with sharpening his fillet knife. We are doing some experimenting with both the angle of sharpening as well as how sharp we get the edge for filleting a fish. ie: does the angle the blade is sharpened or the sharpness of the blade perform better when filleting a fish? Is a toothy sharpening at say 600 grit better than 1000 or 1500, or does an angle of 15dps perform better than say 20 or 22dps? Maybe a combination of both?? We shall see. (One quick comment on the angle for a fillet knife… In my research, there is no agreed perfect angle. I see manufacturers sharpening at 14 or 15dps up to 20 to 22dps.)

    Of course the challenge with a fillet knife is the very low height of the blade when mounted in the Gen 3 vise and then making contact with the clamp. With my current set up I have found sharpening this knife in two steps is best due to the very flexible blade. This still presents a problem for the front half as the stones can still contact the clamp. In my pictures you can see the postion I’ve set and in this case it does make contact on the rear corner of the clamp.

    I know that I can still raise the blade a little more and possibly get clearance or I can move the blade forward in the mount and that will also increase the height of the blade above the top of the clamp. The downside to moving forward being that the blade stiffness goes down. (This is my current solution and I just have to deal with a little more flex.)

    At this stage I am able to get the angle down to about 19.6dps and just clear the clamps. I’d really like to try some lower angles as I mentioned this is a learning experiment.

    So back to the question… would the LAA help in this scenario?

    Common sense says that at some point the stone will contact the clamp if the blade height is low enough. From pictures of the LAA I cannot tell how much thinner the clamp is vs. my Gen 3 stock clamp. Given fillet knives by design have a very low blade height that presents the obvious problem. Has anyone with an LAA done any testing to see what the minimum angle that is achievable given a certain blade height? In my example the height on the left of the clamp is 3/8″ while on the right only 1/4″.  At 19.6dps, 3/8’s works, 1/4 doesn’t. Thus moving the blade forward a little will allow me to sharpen at 19.6dps and not make contact. Again, I’d love to go lower but not sure the LAA will make a difference with such a low height blade.

    BTW, I do own the Tormek adaptor but with the blade being so flexible this just isn’t a workable solution.

    Any comments or thoughts are welcome and appreciated.

    Thanks,

    Dave

     

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    #52259

    airscapes
    Participant
    • Topics: 10
    • Replies: 192

    Do you happen to own the standard vise?  If so, swap it on to your base and get a shorter screw at the local hardware store for the top so your strops don’t hit it.  You will be able to get a lower angle with the STD vise than the gen 3 on a really short knife.  This is what I have been doing to get to 15 degrees on my fillet knife.   The draw back is the angle tilt of the knife in the std vise but that is not really too bad with thin knives.

     

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    #52260

    MarcH
    Moderator
    • Topics: 58
    • Replies: 1881

    First… the question… Will the LAA help in this scenario? I am helping a relative with sharpening his fillet knife. We are doing some experimenting with both the angle of sharpening as well as how sharp we get the edge for filleting a fish. ie: does the angle the blade is sharpened or the sharpness of the blade perform better when filleting a fish? Is a toothy sharpening at say 600 grit better than 1000 or 1500, or does an angle of 15dps perform better than say 20 or 22dps? Maybe a combination of both?? We shall see. (One quick comment on the angle for a fillet knife… In my research, there is no agreed perfect angle. I see manufacturers sharpening at 14 or 15dps up to 20 to 22dps.)  Thanks, Dave

    Here’s some reading to help you understand the science behind your question, (It’s a two part paper):

    https://knifesteelnerds.com/2018/08/06/sharpness-vs-cutting-ability/

    Any adapter, (L.A.A., Riser Block, or Tormek SKA), that will allow you to achieve a lower bevel angle setting will help, but each has their own challenges and difficulties.  I recommend the practical route.  Raise the narrow knife higher in the jaws while still allowing solid clamping.  Center the blade’s position trying to find the happy medium between flexing and sideways stability.  You still may need to hold a hand on the blade opposite the sharpening side to stabilize the knife from flexing too much.  Then I choose a bevel angle you can achieve with the knife clamped in this vise without having stone vise conflict.  I’m also, looking to the future being able to re-sharpen this knife the same method.

    In my experience a 19-20º bevel is a good balance between sharpness and durability for this style knife.  Remember the fish filleting knife is a often used as a combination knife: filleting, boning and skinning.  Those guys I sharpen filleting knives for are always happy with what I do.  I think the sharpening job is in reality more about technique and attention to detail, then about the numbers that describe the edge.  I take filet knifes to at least 1500 grit. The tip is often used to pierce the skin while cleaning fish.  I prefer a smooth cutting edge to cleanly cut and remove the fillets from the bones.

    Marc
    (MarcH's Rack-It)

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    #52262

    Richard
    Participant
    • Topics: 7
    • Replies: 108

    I agree with Marc, you can get a lot lower angle by simply moving the knife higher in the vice.  I sharpened a paring knife yesterday and had it clamped down about 1/4″ from the top, worked great.

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    #52266

    DaveG
    Participant
    • Topics: 4
    • Replies: 6

    Thank you all for the responses. This is a great forum with a weath of knowledge.

    Airscapes… I don’t have the standard vise so will have to make due with what I have.

    Marc… Thanks for the confirmation. At least I am headed in the right direction and can do a little more adjusting with my current setup. Sounds like the LAA probably won’t help much given the blade I am working with. I have seen that article before. (I’m sure it was from one of your posts) While I feel I need to head back to school while trying to digest it all, it does give a good basis for sharp not always being sharp. There are many variables at play and I appreciate your advice to stay in the 19 to 20dps range for the fillet knife.

    Again… Thanks ALL!

     

    #52267

    tcmeyer
    Participant
    • Topics: 33
    • Replies: 1851

    About two years ago, I sharpened a half-dozen filet knives for some friends that do a lot of fishing.  Not having a clue as to what angle would work best, I went with 17 dps main bevel with a 20 dps micro bevel at 1000 grit.  They reported that the knives worked beautifully.  I later watched a TV show which took a tour of the Martinii factory.  The owner said that they only use a 22 dps angle.  Sounds like anything in that range ought to work out fine.

    I use my LAA with my Gen 3 vises and clamp the blade much like in your photos, keeping the flexible tip as close to the vise as possible.  I sharpen one side at a time, so I can hold the handle with the opposite hand to avoid flexing, although I also have a RAM arm and clamp to hold the handle for me.  I also have my original vise with its own base, so I can do filet knives there without the LAA.

    Good Luck!!

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    #52269

    Lay
    Participant
    • Topics: 1
    • Replies: 14

    Victorinox filet knife sharpened to 18 dps at 1000 grit has served me well this summer. I tried my other filet knife (Marttiini sharpened to 22 dps) and did not like it so much. Small difference and probably down to preferences. With 18 dps I can still sharpen it without LAA. I have it (LAA) but don’t like to use if I can get a way without using it.

    My 5 year old son wanted to start fishing with me and we have been fishing and eating fish almost every week the whole summer. I don’t even like to eat fish that much but hey… quality time with my son.

    • This reply was modified 1 week, 3 days ago by  Lay.
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