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Recommendation? >20 degree knife - sharp maker - not getting burr

Discussion in 'Maintenance, Tinkering & Embellishment' started by Bo-dacious, May 9, 2018.

  1. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Hey guys, I've posted about the karambit on the sharpmaker before but I just discovered something new.

    I'm trying to sharpen a karambit on a sharpmaker. The knife is greater than 20 degrees so I have to try to lean the knife to make up for the angle. What I discovered is I'm not getting a burr when I do all the strokes on one side. I did 100 strokes and no burr (not even a tiny one, that I can feel) . I'm keeping the same angle and I'm lowering the handle to keep the alignment of the edge to the rods.

    I used a felt Marker and I'm removing the entire edge of steel with my strokes. I don't know what else I can say to decribe what I'm doing. Does anyone know what I could be doing wrong? Should I try it at a slightly steeper angle to hit that apex?

    Keep in mind I was trying a lot of things on this knife and I had the edge messed up. It was like a double bevel. Then I did 400 strokes per side on the cbn rods to even that angle out. Then I did it at an angle that removed all of the marker from the edge. Shouldn't that work?? I've noticed before on my work sharp that I've removed all the marker, but I didn't get a burr. So I tried a slightly higher angle and it worked. I don't want to ruin what I've done so I'm asking you guys first if I should try at a steeper angle to get a burr.

    Does anyone have any ideas?

    Thanks guys,

    Bo
     
  2. bgentry

    bgentry

    Aug 3, 2009
    Look at the edge for a reflection. I'm guessing it's still not apexed. I'm also guessing that it came with a stupid large angle. Like 25 to 30 degrees per side (50 to 60 degrees inclusive). Just guessing.

    Brian.
     
  3. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Ya it's some dumb big angle. I'm bad at seeing the reflection, I'm not sure if it's part of one side of the edge that I see or it's actually where the apex would be. If it's reflecting light, it's very little. So I must be close to getting it apexed, right?
    What do you think about my idea of increasing the angle slightly?

    Bo
     
  4. flatblackcapo

    flatblackcapo Part time maker, very very part time Knifemaker / Craftsman / Service Provider

    Mar 25, 2012
    I would recommend some form of direct bright light
    These are cheap and work.
    https://www.ikea.com/us/en/catalog/products/20386336/
    A jewelers loupe will help too.
    If you can see what is going on with your edge, it will help you figure out were you are with it.
     
  5. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Thanks flat, I do see a reflection from one side of the edge so I think I'm getting enough light, but I only have a 10x loupe. Maybe I should get a more powerful one as the 10x barely does anything.

    Bo
     
  6. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    But I'm pretty sure I haven't apexed the edge. What I need to know is what do I do about it...

    Bo
     
  7. flatblackcapo

    flatblackcapo Part time maker, very very part time Knifemaker / Craftsman / Service Provider

    Mar 25, 2012
    The only thing to do is hold your angle and keep sharpening until you apex.
    Or you can send it to one of the pro sharpeners on the forum.
     
  8. flatblackcapo

    flatblackcapo Part time maker, very very part time Knifemaker / Craftsman / Service Provider

    Mar 25, 2012
    You can also try wrapping good quality wet dry sand paper around some kind of tube ( paper towel tube, PVC pipe)
    Maybe start with 400 grit. Establish the edge then refine with your Sharpmaker.
     
    Gary W. Graley likes this.
  9. bucketstove

    bucketstove

    967
    Sep 23, 2014
    wipe blade first, use a flashlight , use a dark towel as background
    white walls reflect nicely from the sides while you're trying to get a look at the apex

    Do what is required, you know this
     
  10. Twindog

    Twindog Gold Member Gold Member

    Apr 6, 2004
    It's the burr that tells you whether you've reached the apex. Counting strokes does't tell you much at all, as you're finding.

    With a Sharpie and your 10X loupe, you should be able to see easily whether you're at the apex.

    If you're using the standard stones that come with the Sharpmaker, it can be a long, difficult process to reprofile the edge, especially if the stones are loaded. If you're using the flats, you're touching the blade at only two points, which makes for slow progress. If you're using the corner, you're contacting the edge at just one point, also making very slow progress.

    You might try wrapping a relatively coarse wet/dry sandpaper around a dowel or handle and giving it a go that way. It will be much faster. Just watch your angle.
     
  11. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Flatblack: I tried sandpaper around the rods but I didn't get good results.

    Twin: I'm using cbn rods and I'm on the corners of the stones.

    Thanks guys,

    Bo
     
  12. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    OK I just realized something. I kept sharpening at a steeper and steeper angle until I got a Butt but I noticed I was at such a steep angle that I could see the edge that I was sharpening. I then noticed how I was only removing material from the apex half of the edge, not the shoulder half.
    Guys, am I working on a convex edge and not even realizing it? Did I create it by changing angles? That's the only thing I can think of.

    If it is, what should I do? How should I fix this disaster?

    Bo
     
  13. bucketstove

    bucketstove

    967
    Sep 23, 2014
    Hi,
    post a picture?

    what do you think you should do?
     
  14. flatblackcapo

    flatblackcapo Part time maker, very very part time Knifemaker / Craftsman / Service Provider

    Mar 25, 2012
    You very well could have created a convex edge by not holding a steady angle.
    You can try clamping your knife to the edge of a table and use the rod like a file. with good lighting you might be able to see and hold your angle a little better.
     
  15. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Bucket: I'm trying putting a pen under the sharpmaker and continuing to sharpen until I remove metal from the entire edge. I've almost done that on one side. I'm going to keep sharpening until I get a burr. I can't take close up pics, my phone gets blurry close up.

    Flat: I'm not very good at getting an angle free hand. Although I'm getting better.

    Bo
     
  16. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    OK so I've done 800 strokes per side, alternating 100 per side. I'm still not getting a burr. Seriously. Can anyone tell me why??? I'm starting to get really frustrated. I was thinking of changing the angle by 1 or 2 degrees steeper to hit the apex. What do you guys think?

    Thanks,

    Bo
     
  17. bgentry

    bgentry

    Aug 3, 2009
    How blunt was the edge when you started? If it was extremely blunt, like say a 1/16" wide flat where the edge should be, it would take quite a lot of grinding to bring the bevels together and form a proper sharp edge. The sharpmaker isn't really well suited to removing lots of metal. Are you confident in your ability to detect a burr? If so, one of a very few things is going on:

    1. Extremely blunt edge requiring lots of metal removal.
    2. Very large angle on the edge and you're only grinding at the shoulder. Note that Sharpie can be misleading unless you re-apply it very often. The issue is that as your hand varies the stroke slightly, you might swipe off the sharpie on one part of the bevel, but really not be doing any grinding there. Reapplying sharpie every 10 strokes or so can be instructive to see where you are actually doing most of your grinding. Check the sharpie mark after every 2 or 3 strokes. The place where it disappears first and most strongly is probably where you are concentrating your grinding.
    3. (Unlikely) bad tempered steel or some oddball steel that forms almost no burr no matter what you do.

    As I think I might have suggested earlier, it would be much easier for you to start with a more conventional blade shape. A pure hawkbill like the karambit is difficult because it's a continuous reverse curve and requires a very narrow grinding surface (edge of a stone or similar). I've seen several that looked like they would not ever be able to easily slice media given their huge bevel angles. Some karambits (maybe yours, maybe not) are more of a showoff or fantasy knife, rather than one that is intended to be brought to a sharp edge and used to cut things.

    Brian.
     
  18. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Brian: it was pretty blunted, maybe a bit less than 1/16. I'm pretty confident in my ability to detect a burr.
    It removes most and first at the shoulder of the edge. A slim line of marker remains at the apex. That's why I'm doing so many strokes to slightly change that angle. Should I keep grinding until I start to remove marker from the apex?
    When I tried a different method, grinding at a really steep angle when I had a double bevel, I got a slight burr. So it does make burrs, just bit very big ones.
    I've sharpened regular knives on the sharpmaker just fine. I want to be able to sharpen all knives as I want to open a knife sharpening business.... Some day in the not too distant future.
    OK so your saying not many people care about getting a karambit razor sharp?
    This information has been very helpful.
    I think it was you that wrote 7 secrets of sharpening. I've read up to secret 3 so far. Very very helpful stuff. You are very smart.

    Thanks Brian,

    Bo
     
  19. Torrin

    Torrin

    57
    Jun 16, 2017
    Don't switch sides until you have apexed one side fully.
     
  20. Bo-dacious

    Bo-dacious

    374
    Aug 13, 2016
    Torrin: oh really? Howcome I just do one side? Someone else told me to alternate every 100 strokes. I'll try doing it your way.

    Thanks,

    Bo
     

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