Sharpening question

Discussion in 'Maintenance, Tinkering & Embellishment' started by ironbike, Apr 12, 2020.

  1. ironbike

    ironbike

    14
    Nov 12, 2014
    Hey
    Been a while since I've posted. Just have a couple questions. I have a few blades that need some sharpening. Assembly so I can seem to get a super clean razor edge on where I can push cut paper other blades I just can't seem to get that kind of cutting edge on them. For instance my tops knives CAT & Baja 3.0. tomorrow night work on them They just will not cut cleanly through paper. Is this user error or is it edge geometry? I know these blades are designed for everyday utilitarian style work. I have a blunt force blade that is about 8 in long very heavy but cuts paper with ease and will shave my arm no problem. Any tips or info would be greatly appreciated.
     
  2. How are you sharpening? Freehand,
    fixed-angle system, or something else?
     
  3. ironbike

    ironbike

    14
    Nov 12, 2014
    Freehand on a strop
     
  4. A strop is for refining a sharp edge, not sharpening a dull one. It isn’t going to make a knife that’s not already sharp any better. If it’s not already cleanly apexed and pretty clean, the strop is just polishing a dull edge.
     
    Night Rider likes this.
  5. ironbike

    ironbike

    14
    Nov 12, 2014
    Well it is certainly polished lol. It's like a freaking mirror but can't slice paper. Guess I'll have to start back over with a stone
     
  6. willc

    willc Gold Member Gold Member

    Aug 13, 2013
    Since your edge is nice and shiny this can help you out.
    Now go with a low grit stone and go nice and slow and inspect your angle every couple passes to make sure you are using the right angle.

    I call this see sawing and by going from a very high grit to a low grit helps me see what exactly is going on with the edge and how I need to proceed from there.

    Good lighting and magnification help a lot.
    I shoot for popping hair and push cutting paper off my lowest grit stone.
    Then as I proceed with the next stone I make sure I am on angle and the scratch pattern goes all the way to edge.

    It is very easy to make the knife more dull going to a higher grit stone if I get sloppy.
     
    Night Rider likes this.
  7. ironbike

    ironbike

    14
    Nov 12, 2014
    That's very interesting. I'll give that a try. So just to be clear. I have a couple blades that are easily slicing and push cutting paper, those blades I can hit on the strop a couple times to keep that edge refined?
     
  8. Night Rider

    Night Rider Gold Member Gold Member

    Apr 16, 2018
    willc That is an awesome tip! Thanks for that :thumbsup:
     
    willc likes this.
  9. Yes, if it’s sharp, the strop will help keep the edge that way as long as you do it before the edge is too far gone. But once you’ve lost the apex of the blade, you need something more abrasive than a strop to get it back. The defined apex is what makes the blade sharp; if the bevels don’t meet at a distinct angle, you’re never going to be really sharp.
     
  10. ironbike

    ironbike

    14
    Nov 12, 2014
    Cool. I have multiple blades that cut super clean & shave hair. I'll just keep them going on the strop every so often. Do you recommend green or white compound?

    As for the dull blades they feel like they have an edge but obviously once I hit them with paper they basically just tear the paper. I'll work backwards with a rough stone & back up to the strop.

    How long or how many passes do you think it will take? I'm sure that's a loaded question but figured I ask
     
  11. I normally use white, but not sure if there’d be a noticeable difference. How many passes really depends on how bad the angles are. Sometimes it’s a couple to get a burr, sometimes a lot more.
     
  12. ironbike

    ironbike

    14
    Nov 12, 2014
    Ok thanks. I did the technique where I went down to a low-grade stone and work my way back up. I got the blade from not being able to cut paper at all to slicing it decently. Still not a super sharp edge where I can push cut but it is much better
     
  13. Ourorboros

    Ourorboros

    566
    Jan 23, 2017
    Don't just go up your progression of stones. Your blade should be sharp with your coarsest stone. While you can apex an edge with any grit stone, it will be far faster and easier on your coarse stone.
    Everything after that is just refining the edge. So form your burr on that coarse stone. Remove it. Check it on paper. It should cut paper cleanly, though you may feel the coarseness of your edge.
    Until you are happy with the sharpness - though not keeness - of that coarse edge, do not go up your progression.
     
    000Robert likes this.
  14. HeavyHanded

    HeavyHanded

    Jun 4, 2010
    My TOPS CAT knife came with such a heavily built edge it cut less effectively than any of my hatchets. Pretty sure its made for opening 55 gallon drums, not cutting anything.

    Thinned the tar out of it and now cuts very well, their 1095 has pretty good HT, though again it seems more for toughness than edge retention.
     
  15. ironbike

    ironbike

    14
    Nov 12, 2014
    Ok. Great advice. I left out that I was hitting it on the course stone until it could cut paper. Then I went up from there. Before the course stone it couldn't even cut paper it would just rip.
     
  16. ironbike

    ironbike

    14
    Nov 12, 2014
    That's the only thing I have found with a couple of their knives. I also have their mil spec which is like a razor blade though
     
  17. Papilio

    Papilio

    55
    Sep 6, 2019
    I think that the color is not standardized.
     
  18. HeavyHanded

    HeavyHanded

    Jun 4, 2010
    Don't underestimate geometry when it comes to cutting efficiency. When I first got my CAT even if it was sharp enough to shave arm hair it couldn't slice an apple without it exploding like a log being hit with a wedge.

    Is a totally different animal now, love that little knife.
    [​IMG]
     
    willc likes this.
  19. Ourorboros

    Ourorboros

    566
    Jan 23, 2017
    Well cutting paper doesn't really mean the edge has been apexed. It means the edge is close enough to apexed that it cuts paper.
    You can use anything with loose fibers - like fuzzy felt, old flannel, a cotton ball - to check for a burr if you can't feel it. Just (safely) run it from the spine side to edge and see if fibers catch anything.
    A way to guestimate is when you cut paper. A sharper edge will cut more quietly (as will a keener edge). This assumes same type of paper, not rumpled up, roughly the same speed. A really sharp edge can ride the same point through yards of newspaper without any horizontal movement, with only a whisper.
     

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