A new edge for a Sebenza 25

  • The owner of this Sebenza 25 bought the knife brand new through an official dealer in the Netherlands, but although he was and is still very pleased with the knife itself, he soon found that the factory edge didn't cut too well.
    He tried to improve things with the help of a Spyderco Sharpmaker and a leather strop loaded with some green compound, but to no avail.
    So he sent the knife to me, and the first thing i did was to measure the edge angle.
    According to my Tormek Angle Gauge it measured 50 degrees inclusive on the straight part of the edge, going up to 55 degrees inclusive from the belly to the point.(!)
    This is how the knife looked before sharpening:





    First i removed the apex of the old edge by cutting a few times directly into an old silicon carbide stone, after which i reprofiled it freehand on my Tormek SB-250 Blackstone to an even 30 degrees inclusive.
    This was followed by a Paper Wheel with 220 grit SiC to smoothen the grindlines made by the Tormek, then refined with a second Paper Wheel coated with 15 micron diamond compound, and finally removed the burr with a third Paper Wheel coated with 0.25 diamond compound. (this leaves the 15 micron scratch pattern intact as much as possible to preserve bite)
    The resulting edge treetops the hair on the back of my hand, can slice single-ply toilet paper, and survives a few cuts into my laminated testblock without any visible damage (checked under bright light with the loupe in my Victorinox SwissChamp)
    This is how the knife looks after sharpening:






  • Great work ! Is it possible to send my Sebenza 21 to you too for resharpening ? I have the same problem with the "famous Reeve-sharpness". How much would such a resharpening be from you ?

    Jörg

    2 Mal editiert, zuletzt von JAG ()

  • A few days ago i sent the owner of the knife a message asking him how the edge was holding up in his use, and today i received this reply (translated from Dutch)


    "During our week & a half holiday in Normandy, France i've used the Sebenza 25 lightly, but daily for opening packages, cutting string, and cutting bread (not on a board)
    Afterwards when i pulled the edge over my thumbnail i could feel a few ever so slight irregularities, but these disappeared with just a few passes over my strop.
    I would still consider the knife to be very sharp: it won't treetop the hair on my arm anymore, but it still shaves it effortlessly on skin level."


    This was my answer:


    "To me the higher degrees of sharpness (hairwhittling & treetopping) are in fact only useful to find out how sharp exactly a certain steel will get with a certain sharpening method.
    In daily use however these sharpness levels will vanish quickly as soon as the knife is used for more than just mowing hair from your arm.


    If at this moment the edge is still able to shave the hair on your arm on skin level i would consider that a good result, and actually even a bit above my expectations considering the lower hardness of earlier Sebenza blades in S30V and S35VN (based on previous Sebenza's i've sharpened as well as user feedback)
    My guess is that the hardness in the Sebenza 25 model is ramped up a bit compared to earlier versions, something i consider to be a good thing.


    Those slight irregularities you feel with your thumbnail could also very well be sticky debris clinging to your edge instead of damage.
    Something even slightly sticky can hang on to your edge tenaciously making it many times thicker and more irregular, thereby making it only seem like there is edge damage while in fact there is none.
    My advice would be to only do the thumbnail test after you've cleaned the edge well (i use a soft piece of cotton with some acetone for this) to make sure it's really clean.
    If after this you still feel irregularities then it's truly damage and it maybe time for the strop.
    BTW: using any strop before cleaning the edge of a knife will very quickly lessen the effectivity of the strop by fouling it.


    I would recommend to use the Sharpmaker when the edge is no longer able to shave armhair, as it is way easier to keep your edge sharp with it than it is to make it sharp.
    Also because a strop is no magic wand: when you let your edge degenerate too far a strop won't help you out, no matter how long you keep stropping.( it will even work counterproductive)
    I only use a strop on already very sharp edges to keep them at a certain level (not to get them there), and only sparingly: just a few stroppings per side should do the trick.
    My advice would also be to get yourself a diamond loaded strop as this will work more efficiently on the hard (vanadium) carbides in the S35VN steel compared to your current one with chromium oxide."

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