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Professional knife sharpeners

Discussion in 'Non-Firearm Weapons' started by frogfurr, Jun 1, 2019.

  1. Taurus 617 CCW

    Taurus 617 CCW Member

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    I purchased the TS Prof sharpening system. It is very similar to the Edge Pro but has more versatility and is much beefier. It was fairly expensive with all the options but I sharpen professionally and it does a great job. I use Edge Pro stones and they last for quite a while. 1.5 years so far.
     
  2. JohnKSa

    JohnKSa Moderator Staff Member

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    The key is not being in a hurry. I see some people sharpening a knife and they're moving the blade at super speed as if they're going to get some kind of award for how fast they swipe it across the stone.

    If you want to maintain a constant angle, you can do it easily by moving the blade slowly over the stone. Do it slowly as long as you need to until it becomes second nature and then you can go faster. Even after years of sharpening, I still move my blade relatively slowly compared to some folks who seem to be almost slashing at the stone when they sharpen.

    If it takes too long to sharpen using this method, then you need a coarser stone to start with . Trying to sharpen a knife with a really fine stone takes a lot of patience. Unless your time is really cheap, you'll be better off getting a coarse stone and starting with it to get the bevels set and then only using the finer grits to polish/finish the process.
     
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  3. Slamfire

    Slamfire Member

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    I want to recommend a magnifying glass. I sharpen by hand, no fixtures. I use diamond stones, like JohnKSa mentioned. I could not get great edges on these modern steels till I used diamond stones.

    Older knives, like this 1976 Queen Stockman, 440A was a premium steel to find on a production knife, and was relatively hard compared to the competition. But, in today's world, it is not that hard and you can sharpen the blades and do a good job with a standard whetstone

    vy47yY4.jpg


    These 1970's Green River knives, they were 420 steel, they were good in their day, you can easily sharpen them with a carborundum stone, or an india stone, because they are fairly soft. They are soft enough that you can get aggressive material removal in a few strokes.

    DMDRSKe.jpg

    This is probably 1095 and it is ridiculously easy to sharpen with a standard whetstone.

    XLD60c1.jpg

    But, once knife makers started using really good steels, such as D2

    1oFiRwp.jpg

    NE1FT6C.jpg

    I found it impossible to set the bevel and keep it from getting rounded with the older stones. Diamond stones really made my edges shine with these modern hard steels. I use coarse diamond stones. I set the bevel with the coarse diamond stone, examining the edge and making corrections based on what I see in the magnifying glass. (I use the one on my SAK)

    qol8jFR.jpg

    With that magnifying lens I can clearly see if I am holding the angle or not.

    It is important to see that the edge is centered, you can see this in your magnifying lens. You can also see burrs. For highly curved knives, I break them up into sections. Something like this, I might break up into three sections, at least two. I am going to work on that belly and sweeping point separately and try to blend the contour with the straighter section. You cannot hold a consistent stone to blade angle with such a curve in one long motion.

    Tiu4Kqw.jpg

    To finish, I use a medium India stone, which is the red side of this stone. All I am doing is smoothing the burrs created by the diamond stone. I don't want to change the bevel, just smooth things out. And this might be two strokes per side.

    k4wxpl1.jpg

    I will bet Florindo DiPinto could put on a great edge!

    YhCZpN3.jpg

    It was pedal powered.

    Xw6t6iL.jpg


    Notice the drip can above the grind stone

    1VSls4C.jpg
     
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  4. JohnKSa

    JohnKSa Moderator Staff Member

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    Looking back at the title of this thread, I suppose I should clarify that I do not sharpen knives professionally. I do sharpen (and do some minor repairs on) other folk's knives, and I have had people offer to pay, but I have never accepted any payment.
     
  5. StrawHat

    StrawHat Member

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    sparky,

    Thank you.

    Like most anything, it requires the three P’s. Practice. Patience. Persistence.

    According to my father I received my first set of stones as a present for my sixth birthday. I still use whet stones but also a variety of other tools to accomplish a fine edge in the least amount of time. I still prefer to freehand the angle but the Wicked Edge and similar are useful at times.

    Kevin
     
  6. hso

    hso Moderator Staff Member

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    o_O

    44oA isn't generally considered to be a premium steel any longer and was pretty common on inexpensive import knives for many years. Kershaw and Camillus did a fine job heat treating it and got a lot out if it. It doesn't achieve as high a hardness as 440C, but it can be tougher and easier to sharpen and take a finer edge while being more corrosion resistant. It isn't as "cheap" a steel as many made it out to be, but it significantly was used for rust resistance and a fine finish as well as the cost savings in production and in avoiding warranty issues that a higher alloy might see.
    https://agrussell.com/chart
     

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  7. Slamfire

    Slamfire Member

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    I can understand why cheap Rough Ryder knives are 440A (or B) because the alloy is soft and easy to grind and stamp, but why didn't US companies, such as Queen, use 440C. Ditto for Randall, my Randall's are 440B steel. I used to visit Randall and they never let on that their 440 was B and not C.
     
  8. hso

    hso Moderator Staff Member

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    A and B are easier to grind, very rust resistant, took a razor edge, easy to sharpen (even if it didn't hold it long) . There's nothing exotic about 440 A or B, they just have properties and costs attractive to some manufactures. As to Randall Made's stainless knives, they use B because it gives them the corrosion resistance and better toughness that they're looking for. RMK doesn't push to get the hardness sat the upper range of what the steel will provide anyway so they get an even greater improvement in toughness and they're not as difficult to sharpen. You can get RMKs in 440C or they may simply make them when C is available at a good enough price.
     
    Last edited: Jun 30, 2019
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  9. Valkman

    Valkman Member

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    Those companies also buy a LOT of steel and I'm sure cost is a big factor in what steels get used.
     
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  10. Slamfire

    Slamfire Member

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    Rough Ryders knives are easy to sharpen, but they don't hold an edge. I am very disappointed in the brand, overall the knives are nicely fitted, but they dull too quickly. My older Japanese Parker Eagle brand knives were probably 420 steel, and they hold an edge better than the Rough Ryders.
     
  11. bubba in ca

    bubba in ca Member

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    I've used Arkansas stones and any number of jigs and even angle grinders over the years, so there!
    Now about 90% of my non-machete work is with a set of lansky ceramic rod jigs. The trick is knowing when you need a stone and when you can get it done starting with the diamond rod and then going--quickly--to the medium rod. The fine rod is often skipped for everyday tools.
    The jig sets the angle for you and takes all the brain work and skill out of it. I keep my kitchen knives tuned up with these rods, too.
     
  12. JohnKSa

    JohnKSa Moderator Staff Member

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    A good system that controls the edge angle is going to outperform even a really good free-hand sharpener. It's just not humanly possible to control the edge angle by hand and eye as well as it can be done by a mechanical jig.
     
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  13. hso

    hso Moderator Staff Member

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    For something other than a straight blade instead of swept, curved, or recurved I'd agree completely.

    OTOH, just about every custom maker I know of significant prowess is not using any of these systems. That's probably the difference between us mere mortals and these lords of the blade.
     
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  14. JohnKSa

    JohnKSa Moderator Staff Member

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    Good point. Probably the worst edge I've gotten recently on a factory blade was on one with a pronounced recurve.

    I tried sharpening on conventional stones but the recurve wouldn't allow it. I ended up having to set the bevel with a diamond rod and finish it with a ceramic rod.
     
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  15. hso

    hso Moderator Staff Member

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    I've done exactly that.
     
  16. joneb

    joneb Member

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    How consistent is the grind angle along the length of the blade? It seems like the rod holding the stone would change angles as it moves across the edge.
     
  17. JohnKSa

    JohnKSa Moderator Staff Member

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    This is actually pretty interesting. It is one of those problems where the solution seems intuitive but is wrong.

    It's actually pretty simple to show that the intuitive result is wrong but even then it can be hard to get your head around the results.

    I'll try an explanation, but then I'll provide a couple of videos in case my explanation isn't as clear as it could be.

    Look at the KME sharpener from the side and you will see a triangle formed by the stand, the extension from the stand that holds the blade and the guide rod holding the stone.

    It's important to look ONLY from the side (with the knife point aiming directly at you or directly away from you) so you get a 2D triangle to help visualize things. But why ONLY from the side? Because that's the only thing that matters. The angle of the edge bevel is ONLY important when viewed from the point of the knife so we need to limit ourselves to looking at the problem from that perspective.

    Note that (assuming a perfectly straight edge on the knife) this 2D triangle is the same no matter where the stone is placed on the blade as the stone moves back and forth across the edge.

    The distance from the stand to the knife edge (one side of the triangle) is constant. The distance from the extension that holds the knife upwards to the point where the guide rod goes into the stand (another side of the triangle) is constant.

    The angle formed by the stand and the extension can't change. It's always 90 degrees.

    If you look at the angle formed by the guide rod and the stand (viewed from the side) you can see that it doesn't change either as the stone moves across the edge. Remember we're assuming a perfectly straight edge on the knife--no curve.

    Per the rules of trigonometry, if you have a right triangle (one angle 90 degrees) that has 2 sides and one other angle that never change, then other angle doesn't change either. That's exactly what the 2D triangle is in the case of a knife with a straight edge.

    What it comes down to is that the curve of the blade will result in some tiny variation of angle as the stone moves across the blade edge, but the length of the blade won't change anything. And, as long as the blade is clamped into the fixture in the same position every time, the tiny variation due to the curve of the blade will be consistent. It will vary the same way every time.

    Here's a good video on the topic that may be easier to understand than my trig based explanation.



    Here's another one from a guy who initially thought the angle changed but then looked a little deeper.

     
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  18. joneb

    joneb Member

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    That's what I was wondering, that from the start of the belly to the tip the angle would be more obtuse than the straighter part of the blade.
    If the pivot was farther away from the blade would this decrease the variation?
     
  19. JohnKSa

    JohnKSa Moderator Staff Member

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    This starts to get more complicated to visualize when you start talking about edge curvature, but I can tell you this. If the blade edge made a perfect and complete circle around the guide pivot area, the edge angle would remain perfectly consistent all the way around.

    So let's think about curvature that doesn't form a perfect circle--in that case, yes, the farther the blade edge is from the guide pivot at the clamp point, the less edge curvature will affect the edge angle.

    But what it really comes down to is that the only situations that have any chances of creating any practical difference in the edge angle are pathological cases. It's really not something to worry about at all. I can get a blade very sharp freehanding it and I'm introducing TREMENDOUSLY more edge angle variation into the mix with a freehand technique than you're ever going to get with a properly designed guided system and any reasonable scenario.

    In other words, I probably wouldn't try to use a guided system to sharpen something like a long kris blade with lots of deep recurves. Other than pretty unusual scenarios like that, it's not worth considering.
     
  20. joneb

    joneb Member

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    AwMDAwL2F0dGFjaG1lbnQub3V0bG9vay5saXZlLm5ldEA4NGRmOWU3Zi1lOWY2LTQwYWYtYjQzNS1hYWFhYWFhYWFhYWEifQ.jpg
    Maybe only a bit OCD.
    I am in the process of making a guided blade sharpener prototype similar to the KME I am trying to understand the mechanics of this system. I am hoping to make this fixture from materials I already have. I have some 3/8" stainless round bar stock that is 24" in length I will the horizontal bar at this length and have the vertical bar 12". One challenge will be making a universal stone holder to attach to the horizontal rod along with a blade retention system. I thought magnets could be useful but I don't want debris stuck to the knife.
     
  21. 460Shooter

    460Shooter Member

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    This is an excellent info packed thread. My thanks to the knowledgeable folks for sharing their experience.

    I recently acquired several knives, one in 154CM, one in S35VN, and three in CPM20CV. All of them have different blade shapes. Sharpening is something I need to learn and practice at over the next few years before those tough steeled blades really need it.

    Fortunately I have older cheep knives to practice on, with whatever method I choose.
     
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