no belt grinder how to convex?

Discussion in 'Knife Maker Shop Talk' started by graveyard, Jul 7, 2013.

  1. graveyard

    graveyard Well-Known Member

    i use a side grinder & files so on how can i convex a grind by hand?
     
  2. rhinoknives

    rhinoknives Well-Known Member

    You can file the top third of the knife at 10-20 degrees depending on how tall of a blade, and then the bottom third of the knife at a corresponding degree then round the middle with a file to match.

    For finishing, I used corrugated cardboard with sandpaper and rolled the knife. It a lot of hand work but you can achieve a smooth symmetrical grind and finish with patience and a large can of elbow grease.

    I hope this helps, I am sure there are other ways to do this without a grinder?

    Laurence

    www.rhinoknives.com
     
  3. LiamLynch

    LiamLynch Well-Known Member

    I filed the edge like I would to get a flat grind by draw filing. I used a sanding block to finish the flats to 120 then a soft sanding block to sand the rest of the blade, I started from the flat and progressed to the beveled area and it made it curved. I got quite a nice Appleseed grind.
     
  4. rhinoknives

    rhinoknives Well-Known Member

    Liam's method sound easier than what I did years ago. The cross section of a apple seed is what we are after here.

    Laurence

    www.rhinoknives.com
     
  5. LiamLynch

    LiamLynch Well-Known Member

    You don't even have to try, it happened by accident when I did it but I wasn't complaining. You can use the handle of the file to keep the angle roughly the same. Part of the reason it goes convex is the irregularity in filing though. I guess if you used precision equipment it would be slightly flat in areas but you can barely notice, it feels like a smooth curve.
     
  6. Geoffrey

    Geoffrey Active Member

    I use an automotive sanding disc, I have used this on axes and on knives. I convexed an RTAK for a friend with nothing more than a drill and the automotive sanding disc attachment.

    [video=youtube;fgsy2SusaO4]https://www.youtube.com/watch?v=fgsy2SusaO4[/video]
     

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