Question to Chris about Sebenza blade grind

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JohnW

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This is mainly for Chris, since he made the decision to do this (I'm assuming), but the opinion of others is always welcome.

I'm wondering about the convex edge on the Sebenza, in combination with the hollow grind that's used. Is it necessary to the overall strength of the blade?

I ask because I don't have the equipment to grind convex edges (such as a thick strop, or wheel). I only have a Sharpmaker, which after enough time is going to turn that beautiful convex edge into a plain double-bevel edge. (BTW- Check out the Sebenza's blade grind under a microscope if you can. It's very well done).

Would a double-bevel edge significantly weaken the blade? Is the BG42 strong enough to support a "straight" edge, rather than a convex one?

Now I know I can return it for sharpening, but I hate doing that unless necessary. Self-sufficiency has always been attractive to me, and if it's a matter of having the right equipment, that's what I'll do.

Thanks for your attention on this matter, Chris. You've yet another Sebenza lover in the ranks.
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Well, I'm not Chris, but I give it a try.

A convex edge on a hollow ground blade? That is actually new to me... My guess is if the edge is really convex that the final edge was done with a slack belt. A wheel would cause just the opposite effect, a concave edge.

My suggestion, don't worry about if the final bevel is convex or flat, there should be no difference in blade strength.
 
I also am not Chris, but I'll offer my two cents and a bit more change.

You can sharpen your blade to a convex edge using sand paper and a soft medium underneath (leather or styrofoam works, I have heard). It may be easiest to secure a strip of sand paper using a thin coat of some type of glue on styrofoam and proceed to sharpen using a "stropping" motion. Run through the grits of paper until the desired edge is formed!!

Perhaps Chris made that decision because the convex edge is a little stronger than a "normal" edge and with the high hollow grind he uses that may not be a bad idea. If you can get a hold of a copy of Wayne Goddard's new book you can see why a convex ground blade can be made to be extremely sharp so a convex ground edge is good in and of itself as well.

Your other option is to get a Bader BIII grinder!!! That is what I recommend!

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"Come What May..."
 
JohnW

I e-mailed CRK about the convex edge on the one piece range awhile back and got the following reply from Bridgett.

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I did get with Scott, our shop foreman, about your first question and this is what he explained to me.

The knives do have a very, very small convex edge on the cutting edge. We sharpen the knives with a contact wheel and them buff them with a hard felt wheel, which again puts a very small, small convex grind on the cutting edge.

We recommend for sharpening the Spyderco Tri-angle sharpener. This is what we touch all our knives up with and the angles are set up perfect with the angels we use.
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I've found the Sharpmaker perfect for my Sebe's and Umfaam.

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Frank Norman
Frank's Page
 
I'm not CHRIS but I play him on TV, and I find the sharpmaker to also keep the edge nice and sharp but I also use a leather strop with polishing compound for a final finish on the blade, razor sharp when said and done.

G2

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"The Road to Hell is Paved with Good Intentions!"
Take the time to read your Bible Now, don't be left behind...

G2 LeatherWorks
 
JohnW,

The convex edge is part of the whole edge retention quest. A convex edge will hold a better edge than flat bevels. A convex edge allows one to use a more acute cutting primary bevel and yet still have a rugged cutting edge. This is not a new idea or only one method of sharpening. I was one of the few who introduced this method to manufactured knives around 11 years ago. There are many companies out there that buff the cutting edge but there are none that do it quite like we do. I spent about 6 months perfecting this method and it works very well.

To maintain the edge on your Sebenza I recommend the Spyderco Sharpmaker, especially the one with the double angles. Sal Glasser really did a good job on this system. If you want our edge, you will need to send it back to us. Once every two years should be quite adequate.

Thanks for the great question and comments from everyone.
Chris
 
Gee, my Granpa used convex edges. He has been dead for over 11 yrs. I bet he would be surprised at this new fangled method.
 
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