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Cant keep a knife sharp?

Discussion in 'Non-Firearm Weapons' started by Axis II, Mar 13, 2018.

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  1. ugaarguy

    ugaarguy Moderator Staff Member

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    It depends on the steel. Steels like 12C27, AEB-L / 13C26, 14C28N, VG-10, and similar steels seem to perform best with a finely polished edge. Other steels like S30V, S35VN, M390 / 20CV / 204P, and similar have been shown to keep a working edge longer with left a more toothy edge stopping at 600 grit media.
    Even with sub-optimal sharpening that seems very likely to me as well.
     
  2. Axis II

    Axis II Member

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    When i use the lansky i start with course if its really dull and go 25 strokes against the edge or towards the clamp/away from me and then flip it and do another 25 and flip it again and do say 23 strokes and flip it and the same on the other side until i get to about 15 strokes and then i will do the same on each side until down to 1 stroke on each side. I do this for each stone. When i run the stone over the knife i push it towards the tip of the knife if that's what you mean about moving it toward the edge. So if the handle of the knife is to my left i will run the stone left to right.
     
  3. Danoobie

    Danoobie Member

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    This is all fine input. I would also consider getting some sort of serrated blade (takes a tapered round end hone to sharpen) for thick stuff, like cardboard,
    then the straight edge for the finer stuff. Two blades will divide the work, putting less stress on the one blade.
     
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  4. ugaarguy

    ugaarguy Moderator Staff Member

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    There's really no need for that. Properly heat treated VG-10 or higher grade steel will cut cardboard all day and stay sharp. Step up to M390 or better and you can cut cardboard for a week or more without even needing a touch up. I've done it with my CTS 204P blade ZT. From experience I'd rather have a good plain edge than a serrated edge too.
     
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  5. WrongHanded
    • Contributing Member

    WrongHanded Contributing Member

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    I'm later to the party but....

    I've had good results with the credit card sized DMT "plate" sharpeners. I run a coarse sharpener along the length of the blade on both sides to reprofile a little if needed. Then use the same one by pulling from edge to spine as I run it down the blade, alternating sides. I watch the angle to make sure the sharpener only just pivots onto the edge of the blade. Then I repeat that with a fine plate. After that I strop it on the inside face of a leather belt (sometimes the belt I was just wearing). Never used any compound on the belt, but the blades all pop hairs off my arm when I'm done.
     
  6. GLOOB

    GLOOB Member

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    It sounds to me like you have successfully used the "microbevel" or "high pass" method.

    But FYI, if you repeatedly sharpen at only this new steeper angle, you will in all likelihood start to develop a bur, again. I say this as a sharpening junky of the highest order and with the understanding of your paticular sharpening system and likely condition of your stones (pretty darn flat with minimal to no slurry). So don't fall into the trap of thinking that the absolute angle is what changed anything. Changing pressure might have helped a little. But the most significant thing you did by taking the already sharp knife and steepening the angle is that you are lifting the bevel that had been established and you are putting just the edge of the knife against the stone, so the stone is working a much smaller area of steel - this is what allows the stone to efficiently cut away the bur rather than just make more bur. BUT you are very quickly establishing a new bevel. Once you sharpen the knife a few times, perhaps, you will have largely erased the old bevel and the new 30 degree bevel will be almost as big in surface area as the old bevel. And this is where the bur will likely return in your future sharpening endeavors, even if you get a finer stone like a sapphire (which is quite hard-wearing and non-slurrying, as are most of these small, guided-system fine stones). If you are not aware of this effect, and you continue to sharpen at this new "good" angle of 30 degrees, the edge you make will gradually degrade, the bur getting bigger and bigger each time you sharpen, and you will probably shrug it off as nothing, at first. Until one day you realize your edge is definitely subpar, and you may start to wonder what phase the moon has to be in, in order to get a good edge. This kind of experience is what drives a lot of people to conclude that a specific tool/method, such as loaded strop or a specific brand of stone, is the only way to get consistent results. But if you understand what is happening, you can employ a wide variety of mediums and methods and get exactly the results you expect with no inconsistency or chance or luck and be able to maximize the results of any given tools/stone.

    So the gist of this is... the sure way to repeatably achieve the particular result you just achieved is to essentially repeat how you got here. E.g. sharpening at 25 degrees and finishing at 30 with just the finest stone. But again, this is only one of many ways to leave the edge with a minimal bur.
     
    Last edited: Mar 22, 2018
  7. jmr40

    jmr40 Member

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    I've been using one of these for a while. Pretty simple and easy to use. Not too expensive and with a built in 20 degree angle guide.
    https://www.amazon.com/Work-Sharp-S...0213&sr=8-4&keywords=workshop+knife+sharpener

    You don't have to spend 3 figures for a quality knife, but I do think you'll be better off with something a little better quality than what you have. Cheap knives require a lot of time honing your honing skills.
     
  8. Axis II

    Axis II Member

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    Well guys i think we fixed my issue. I had to cut several pieces of half inch thick poly rop yesterday and both sides of the knife still have that sharp feeling. In the past if i did this i wouldn't be able to feel anything on the edge so i think you guys helped me fix my issue and i thank you very much but only time will tell.
     
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  9. Mauser lover

    Mauser lover Member

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    Late to the party, but...

    I use a Lansky. Five stone set, with the 1000 grit yellow stone is my finest. You don't really need that one even, but it makes it nice and shiny!

    I do a convex thingy with my Lansky. I sharpen until "good enough" with my coarser grits, and then finally finish with one notch more obtuse blade angle with the 1000 grit stone. That way it narrows down the blade slightly behind the edge so it is easier to sharpen next time, as well as me not having to pay such minute attention to EVERY stroke. Saves me some time and aggravation. I usually start at the 20 notch, and finish at the 25 notch.

    One trick is to use a Sharpie (or other non-branded equivalent marker) on the edge, and when you grind off the ink on the very edge you are finished!
     
  10. Axis II

    Axis II Member

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    Well gents I've put this little Gerber para frame mini to the test since we last talked. Apples, poly ropes, boxes, plastics packages and sitting here now I ran it on my arm and it took hair off! It took about 5 swipes but it popped hair.

    I think the key was start at a 25 and ended at 30 degrees. I'm going to touch it up with the extra fine tomorrow.
     
  11. ugaarguy

    ugaarguy Moderator Staff Member

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    It sounds like you put a micro bevel on it which gave you better edge stability.
     
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  12. JohnKSa

    JohnKSa Moderator Staff Member

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    Yup. Going back with the steeper bevel right at the end made sure you didn't end up with a burr on the final edge. So sharpen as normal with the 25 degrees and then you only need to do a few passes at 30 degrees when the 25 degree edge is in place.
     
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  13. Axis II

    Axis II Member

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    I'm very pleased with the outcome. Before if I cut that rope and a box it was dull as a butter knife. This edge I can feel the sharpness on both sides when I rub my finger on it.
     
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