All about burrs…

Discussion in 'Sharpening Station' started by Michi, May 3, 2019.

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  1. May 3, 2019 #1

    Michi

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    DisconnectedAG likes this.
  2. May 3, 2019 #2

    KingShapton

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    Thank you for sharing.
     
  3. May 3, 2019 #3

    SeattleBen

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    Like! Thank you.
     
  4. May 3, 2019 #4

    Carl Kotte

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    Super!
     
  5. May 3, 2019 #5

    Nemo

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    This is very interesting. Thanks Michi.

    Then again, now my head hurts...
     
    Last edited: May 3, 2019
  6. May 3, 2019 #6

    Knife2meatu

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    So good! Thanks so much @Michi. Cheers!
     
  7. May 3, 2019 #7

    refcast

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    Thanks a lot.
     
  8. May 3, 2019 #8

    McMan

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    Good find, Michi!
     
  9. May 3, 2019 #9

    hititlong

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    Wow. this is gold
     
  10. May 3, 2019 #10

    Midsummer

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    Interesting..diamonds and CBN. And Larrins research was referenced.
     
  11. May 3, 2019 #11

    Grunt173

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    That's some good stuff.Thanks.
     
  12. May 3, 2019 #12

    Nemo

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    On further reflection about this, I'm interested to know what expert sharpeners think about the ieda that steels with a high carbide volume require diamomds to cut the carbides in order to get them propperly and durably sharp.
     
  13. May 3, 2019 #13

    chinacats

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    I'm no expert but have never owned a knife (any steel) that couldn't be sharpened using waterstones. In fact after watching mc sharpen using a cinderblock and cardboard I'm not convinced there are any real rules.

    Nice link overall very good stuff.
     
  14. May 3, 2019 #14

    ian

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    Nice read. Not sure exactly what the takeaway is for someone freehand sharpening typical carbon steels that one discusses on this forum.

    Mostly what I learned is that I shouldn’t deburr on a cork. However, I’m a little confused about whether to deburr with edge trailing or leading strokes, or what. (It was interesting to read about the benefits of edge leading strokes, but many of the experiments mentioned clearly require more control than one can hope to have when freehand sharpening.) Probably I’ll just keep on using both with progressively lighter pressure, and then switch to edge trailing at a slightly higher angle on a loaded strop.
     
  15. May 4, 2019 #15

    Dave Martell

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    On the issue of de-burring by pulling through a cork/wood, etc.....

    This paper states that this is a negative thing to do and shows us why. I would agree that leaving an edge as is after the de-burr pull off makes for a messy less sharp and weak edge, however, I would suggest that there can be a positive from doing this type of burr removal. I say this because I find that I can't get an edge as sharp, or to last as long, if I don't de-burr by pulling the wire edge off.

    I find that not de-burring sufficiently, before final stropping or further high grit edge refinement on stones, does not allow the subsequent abrasives access to the (root) of the burr thus leaving a weak edge. For this reason I remove the wire burr before final stropping or further high grit edge refinement on strops and/or stones.

    I believe that the strong lasting edge exists at the root of the burr being removed and that this is THE key factor in getting an edge to last longer more than any one thing.
     
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  16. May 4, 2019 #16

    ian

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    Interesting---that does make sense. Thanks for the perspective.
     
  17. May 4, 2019 #17

    Nemo

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    Dave, your knives have arrived as sharp as I have ever experienced and the edge retention on these edges is prolonged (for thise who don't have one of Dave's knives, the cardboard knife sheath says "caution sharp knife" and this is not a marketing ploy, the knife is super scarily sharp). I'm therefore curious about your deburring technique.

    IIRC, you said that for maximum sharpness, you find it important to deburr fully after each stone in your progression? Does that include the cork/ felt block treatment after each stone? What is your deburring process after each stone?

    After your final stone, do you strop on felt loaded with diamond?

    Is your process any different beteeen carhon and CPM knives?
     
  18. May 4, 2019 #18

    MrHiggins

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    From what I know from trial and error, I'm in total accord with Mr. Martell. Deburr, then lightly finish your process.
     
  19. May 4, 2019 #19

    Dave Martell

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    I've gone through a gazillion methods over the years but some of the early surprises that had me scratching my head have kept coming up over and over in different ways that I couldn't ignore them. One of the things that I stumbled upon was how much sharper I could make a knife if I double sharpened it. OK I didn't exactly do a complete double sharpening session but I would re-do the finer stones, say 5k on up, after de-burring. Later on I was to find that when I tested for edge longevity doing this same thing helped a great deal to make an edge last longer at a higher level of sharpness than could otherwise be achieved.

    So at some point I started to follow Murray Carter and many other's advice in pulling the edge through wood and this helped. This led me to corks and everything else I could find to try. Then I was sent a sample of a compressed hunk of rock hard felt (block) and I had found the perfect tool for the job. At this time I was using the block in between every stone and was getting the best results ever. Those who have taken a class with me in the last 7-8 yrs have likely been shown to do this and that's because I know it works and will do so for them. These days I only pull through the block after all stones (or belts) but before stropping. I skip using the block between stones now just because I've got better at stone sharpening and minimum burr formation so there simply isn't the need but I still teach to de-burr by pull through after each stone.

    For final finish, I use diamond spray on a leather belt (it's just faster than using a felt pad) for double bevels but for single bevels I use diamond on felt for the front (bevel) side and a finishing stone for the back (to keep it dead flat).

    No differences for me regarding steel type in what I do, however, there can be extra work required for some steels/heat treatments/makers/etc.

    Thanks for the kind words on my work Phil. :)
     
    Last edited: May 4, 2019
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  20. May 4, 2019 #20

    Nemo

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    Thanks Dave. I'm going to try the double sharpening, I think.

    To me, it makes sense if you think of it almost like a prolonged cleanup of the edge.

    I'm still hoping to get over to PA one day for a sharpening lesson.
     
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  21. May 4, 2019 #21

    Dave Martell

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    What's taking you so long to get here? It's not like you live on the other side of the world. :D
     
  22. May 4, 2019 #22

    Huntdad

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    Thanks for sharing Michi! Thanks to the others for sharing their thoughts.
     
  23. May 4, 2019 #23

    Nemo

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    I'll get there one day...
     
  24. May 5, 2019 #24

    Benuser

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    Not sure I do understand correctly all of @Michi 's attachment, but I have noticed the following.
    Often a burr appears before the very edge has been reached, according to the marker trick. Very clear burr, I can feel, and see with a 8x loupe. I only raise a burr once, with a medium-coarse (Chosera 400), no huge pressure. Not specially looking for raising a burr on the finer stones, as once the bevels have met, they appear within a few strokes. With both carbons and stainless, more with the last, but even with very finely grained ones as 12C27. As if some rearrangement is taking place.
     
  25. May 8, 2019 #25

    Sailor

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    Very enlightening thank you so much fir posting that.
     
  26. May 8, 2019 #26

    Knife2meatu

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    I wouldn't think this possible; assuming we're talking about a burr observed on the side of the blade opposite the abrasive. Although after re-reading your post, perhaps I don't understand "the very edge [being] reached" as you do.

    Based on the great diagrams in the OP's document, it seems to me that the interaction of the abrasive and base metal at the edge is by definition what results in both positive and negative burrs. So I can't imagine how a burr could form without the chip reaching some kind of edge.
     
  27. May 20, 2019 #27

    captaincaed

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    I'm a bit late to the party, @Nemo just referred me here. If one Wanted to try felt and diamond spray, where would they go looking? There are a couple sellers I know of, but they don't seem well liked here...
     
  28. May 20, 2019 #28

    Dave Martell

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    Well, when I'm selling something it comes off as sort of crappy to say Buy Here but I can help if you can't find it anywhere else. ;)
     
  29. May 20, 2019 #29

    Nemo

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    Probably easiest to get them off Dave Martell. He sells the stuff that he uses. PM him for details.
     
  30. May 20, 2019 #30

    psfred

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    A burr forms from the apex bending away from the abrasive. With coarse abrasives, it's possible to deflect the bulk of the edge upwards before it is actually contacting the grains of the abrasive, one reason it's best to finish each stone in a progression with light pressure. Stainless steels are worse about this than carbon steels -- I've managed to produce a very large "fin edge" learning to sharpen yanagibas (or not learning, as I'm not positive I've actually mastered them yet). Minor bend in a cheap knife resulted in a fin edge about 1/16" wide when it finally started to break off without me ever realizing I was near the edge.
     

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