View Full Version : sharpening convex knives

05-06-2011, 03:34 PM
Mods, if this would be better in Woodpile, please go right ahead and move it
Good day all

Have seen a number of threads on sharpeners here, I know some love the Warthogs, some the APEX, and a host of others, but I have a unique situation to ask about.

Recently scored a new cleaver/knife. Unlike all my other knives, which are double or single bevel knives, this one has a convex blade. Most of what I've been able to glean about sharpening them seems to end up going back to sharpening on a somewhat slack belt sander belt. Others say a strop and compound will be enough.

Not planning on running out for a belt sander any time soon, and this is a pretty sturday blade, and currently is shaving sharp so I'm not overly concerned now. Just want to be sure I know how to protect and preserve my investment. With the vast combined knowledge of everyone out there, I'm thinking somebody knows a little something about them?

05-06-2011, 04:02 PM
Did a quick search on this page: http://forums.egullet.org/index.php?/topic/26036-knife-maintenance-and-sharpening/ which has everything you want to know about knife maintenance and found this info:

Sometimes known as hamaguri-ba, the convex edge arcs in a rounded curve down to the edge. Thus the final edge is the intersection of two arcs, creating a very sharp edge with more metal behind it than the standard V-edge. Convex edges are generally formed on a slack belt grinder, so they are difficult for the home sharpener to achieve. This can be remedied with the mousepad trick found later in the tutorial. See the Convex Grind FAQ (http://home.nycap.rr.com/sosak/convex.htm) for sharpening methods and a comparison of the convex edge with other edge types.

Convex Grind FAQ (Link was dead but found this)

The Mousepad Trick:
Can be found in the first link above on knife maintenance. Describes how to use sandpaper and a mousepad to sharpen a convex edge. The Convex Grind FAQ above also mentions this technique.

Personally I've never sharpened a convex edge, so I can't vouch for any of the methods above.

05-06-2011, 04:23 PM
Thanks Saiko,

I emailed Ben Dale of Edge-Pro, and he recommended giving up the convex edge and put on a flat edge. I think I will hold off for a while on that until I see how I like the performance of the convex edge. I did see the mousepad method online as well....but think I'd need a big mousepad. Total length of this is 16", blade is 11

05-06-2011, 04:51 PM
I emailed Ben Dale of Edge-Pro, and he recommended giving up the convex edge and put on a flat edge.

Always an option. Any new chef's knife I get I just grind a new 17 degree V-edge on it, no matter what the original edge was. Personally I use an Edge-Pro Apex.

05-06-2011, 05:00 PM
Thanks Saiko, The forum by Chad probably has all the information I'll ever need for sharpening. I usually have mine done professionally when I do have it done. I certainly do not want to mess up a perfectly good blade by using the wrong angle. My dad and grandad were masters but they were always sharpening so I guess it really comes down to a lot of practice and probably wasted blades unless youy know how to get one back to the original angle. Thanks for the informative post. :thumb:

05-07-2011, 01:49 AM
You don't have to use a mousepad, just something with a little bit of give to it. In fact, I've read where some people don't like them because they can be too soft and cause the edge to be rounded over. I personally use a cheapo HF 1 x 30 belt sander to sharpen convex blades along with axes, machetes, and other things as a convex edge can be put on just about any blade. I don't think I would go that route for only one knife though. The videos on this (http://www.knivesshipfree.com/pages.php?pID=4&CDpath=0) site give a good explanation of convex edges and how to sharpen them.

05-07-2011, 06:29 AM
You are correct about the mousepad being too soft and removing your edge if you use too much pressure. Thicker leather works better with the sandpaper as it is more forgiving for those with a heavy hand.

Oh, and how do you know if your angle is correct? use a sharpie and mark the bevel almost right on the edge and give it a couple strokes then you can see where in your stroke on the blade your angle was off. The goal is to remove the sharpie mark off the edge in an even manner.

05-07-2011, 07:32 AM
Smoke,use a leather belt and drag it several times each side and you should be good.
Hope this remedies you deliema,and