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Thread: convex edge sharpening?

  1. #1
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    convex edge sharpening?


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    How do you guys sharppen a convex edge?

  2. #2
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    I use a strop, currently loaded with diamond paste. Check out YouTube, they have videos on how to strop and even establishing a convex edge using sandpaper.

  3. #3
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    After seeing all those knife sharpens at the store I was thinking of something like a couple of nail files rubber banded together. What do you think about that? Ones with the padding in between them.

  4. #4
    If you're looking for a do-it-yourself solution you're better of with wet/dry sand paper and a mouse pad. Nail files stuck together are probably not going to be abrasive enough. Also a good strop is not expensive. You can get a knives plus strop block for finishing for around $20, or a double sided hd compact from stropman with 2 compounds for about the same.

  5. #5
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    I've used the good old sandpaper-on-a-mousepad technique to pretty good effect, like mkjellgren mentioned.

    The sandpaper, mousepad, and strop are cheap as free. The strop isn't even absolutely necessary - a few sheets of newspaper a la Murray Carter will serve to finish off the edge.

    I'd recommend getting sandpaper in the following grits: 220, 1000, 1500, and 2000. Work through those and then use a few sheets of newspaper at the end and you should have an extremely serviceable edge.

  6. #6
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    Have you watched these videos yet? http://www.knivesshipfree.com/pages.php?pID=4&CDpath=0

  7. #7
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    I use a pocketstone from Fällkniven, a DC4 diamond /ceramic stone and a leatherstrop loaded with Autosol chromepolish.
    Here shown with a custom Fällkniven KoltKnife + firesteel and JRE sheath.

    IMGP4758.jpg

    Regards

    Mikael

  8. #8
    Wet&dry sandpaper on a mousepad backing is always a great way to go, then either buy yourself a nice strop or make one (really not hard at all, get some leather, a bit of wood and some glue) and some strop compound. Black compound for more aggressive removal of steel and get some white compound for making that edge really fine. Green compound is actually redundant if you can get some white compound.

    Also, if you want to sorta convex other knives which aren't (like folders) and by that I mean making the cutting edge convex then I like to use diamond plates to reduce the thickness of just the shoulders of the edge (not the cutting edge itself) and then progressing to sharpen on wet&dry and finally strop the edge. This way you can keep the strength of the edge but because the shoulders have been thinned down and rounded, your new edge will have a lot less friction when cutting through things because the tangential pressure to the cutting edge is spread over a wider surface area. Maybe this helps as a useful tip, maybe not but it's what I like to do to my folders (Y)

  9. #9
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    I use a well worn 220 grit J-Flex belt on my grinder.

    God, grant me the serenity to accept the knives I cannot buy, the budget to buy ones I can and the wisdom to know the difference.
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  10. #10
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    I use fat toad or DLT double strops with BRKT black and white compounds then KSF strop with CrOx

  11. #11
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    Quote Originally Posted by FoxholeAtheist View Post
    Cool! Thanks for sharing that.

  12. #12
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    I've used all 3 of the common methods to convex blades successfully, those methods being 1) wet/dry sandpaper over a forgiving surface such as a mousepad, 2) compound loaded strops and 3) slack belt sander/grinder. All of these methods are proven to work, but if it your first time convexing I would recommend the wet/dry sandpaper method as it is cheap, effective and hard to screw up. The downside of wet/dry sandpaper sharpening to me is that it is just not as fun as the other methods.

    Strops and compounds are as easy to work with as wet/dry sandpaper but I find them more rewarding to use as well as more expensive. Experimenting with different compounds and substrates and how they effect the blade edge can make this sharpening method a complete sub-hobby for knife aficionados. I find this activity a great stress reliever.

    Belt sanders/grinders are the quickest but also the most expensive and easiest to screw up a blade, most commonly being the rounding of the tip. Expensive Hobby Warning: sanders/grinders are fun to play with and the next thing you know you are upgrading and/or collecting equipment and will have to explain to your significant other why you are receiving Christmas cards from places like Super Grit and Micro-Mesh. An excellent entry into slack belt sander sharpening that is easy to master and reasonably priced is the Work Sharp sharpener. I recommend searching and reading forum discussions, watching videos on the subject and practicing with beater blades before working up to convexing any quality knives with power equipment.

  13. #13
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    To me the nicest thing about these methods is they get you into sharpening knives freehand. I now convex all my knives, setting the edge bevel to what I think suits the knife, steel type and use. You'll learn so much more this way than using something like a Sharpmaker (which reminds me I must sell mine)

    Enjoy the journey.

    Sam

  14. #14
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    I also use sandpaper mode to thin wall on a rubberized surface (mousepad)

  15. #15
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    Jun 2007
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    Agreed.

    Convex edges are the Squirrel's Nuts!

    I have used sandpaper over the mouse pad with fantastic results. It is cheap and easy. Now, I have a heavy, dense rubber base pad (from Tandy Leather, deisgned to go under a bit heavy stone for pounding leather). The dense rubber pad allows me to use more force without dulling the edge. It lets me remove metal faster if I am re-profiling.

    I have a home made strop bat, and I use #6 metal polish from Harbor Freight. The stuff was like $3, and I am still only 1/2 way through the stick after longer than 6 years?

    I keep meaning to buy or make a better strop, but the old one is still making my edges hair whittling sharp, so I have not bothered.

    I also have a 1x30 belt sander disk grinder combo from Harbor Freight. I use it on bigger knives (or when re-profiling D2 steel, or other big jobs).

    The belt sander makes big jobs so much faster. 20 minutes instead of days!

    I was showing Scouts how to sharpen, and I took a full blunt, dented throwing knife to hair jumping sharp in about 3 minutes for them.

    But, you can screw a knife up in an instant with power tools. So care and practice on cheap knives is helpful.

  16. #16
    Honestly, after you've convexed it in the first place you can pretty much just freehand sharpen it like a normal knife. The natural slight variation in your strokes will maintain the convex and the main advantage comes from having blended the geometry of the shoulder transition, so it's not gonna' hurt anything. As long as you aren't using jigs or clamps or what have you pretty much every knife out there ends up convexed over time. Don't sweat it too much.


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