Can't get Sebenzas sharp with Sharpmaker

sailfish

sailfish

Joined
Jan 1, 2019
Messages
1,756
I've had Sebenzas for around six years and have been sharpening them on a Spyderco Triangle Sharpmaker just as long. The problem is, I seem to only be able to get them decently sharp about 10% of the time. When that one good time does come around, I think I finally figured it out only to fail again the next time. I've done every possible think I can think of; brown rod, white rod, rod flat side, rod corner side, 40 degree, 30 degree, alternating blade edge sides per swipe , one edge side at a time, stropping every few swipes, you name it. I've done the Sharpie marker on the edge and I'll sharpen until it's all gone and the knife is still dull as a butter knife. When I sharpen one of my Spydercos on it however, a few swipes will have it sharp as razor. I just don't get it. It's gotten so aggrevating that it's pushed me to the brink of selling off all my CRKs more than a few times.

What on earth could I possibly be doing wrong?
 
Interesting problem with a number of possible answers.

Blues is correct that leaving a burr is by far the most common problem that people have with getting an edge sharp. So I'd check for that first. Run a fingertip along the side of the blade, from spine to edge. Do this on both sides, trying to feel for the presence of a burr on one side. If you feel it, there's your answer.

The other possibility is that you are not consistently reaching the apex. Put the knife on a surface, spine down. Shine a strong light on the edge. Do you see any reflections on the apex? If so, you don't have a proper apex. One could imagine removing all the Sharpie without completing sharpening by mostly sharpening above the apex, and occasionally dipping down to reach the apex. Try putting on the Sharpie and just doing one stroke on each side, just the way you do when sharpening. Does the removal of Sharpie extend all the way to the edge on both sides? If not, it's possible that you're mostly sharpening in the wrong place.
 
Then I don't know...if you're certain that you're apexing and not rounding it off. Someone smarter than me will come along shortly.

BTW, what steels are your CRKs?
 
UncleBoots said:
The other possibility is that you are not consistently reaching the apex. Put the knife on a surface, spine down. Shine a strong light on the edge. Do you see any reflections on the apex? If so, you don't have a proper apex. One could imagine removing all the Sharpie without completing sharpening by mostly sharpening above the apex, and occasionally dipping down to reach the apex. Try putting on the Sharpie and just doing one stroke on each side, just the way you do when sharpening. Does the removal of Sharpie extend all the way to the edge on both sides? If not, it's possible that you're mostly sharpening in the wrong place.
Click to expand...
It would appear this is probably my issue. Could I assume this is because of the "convex edge" CRKs come with from the factory, and why I don't seem to have this problem with my other knives? This would also explain why I seem to have had better luck when I would hold the knife to the rod at a slightly broader angle than plumb.

xcuIZrI.jpg
 
The Sharpmaker has a set angle. If the edge angle on the blade in question does not match, you need to work it until it does. Also, make certain that the Sharpmaker is on an absolutely horizontal surface. Use a level to check the horizontalness of the surface upon which you are setting the Sharpmaker. Half a bubble off plumb is enough to throw it off.

If the surface is horizontal, use the Sharpie trick.
Sharpie trick:
Blacken the blade bevel with a Sharpie. Take a few strokes on the Sharpmaker. If you can still see black on the bevel at the edge, the Sharpmaker is not sharpening the cutting edge.
 
The problem with systems like the sharpmaker is they assume you're working with a perfect V edge, and most of the time you're not. From what I can see in the picture you posted you just need to grind off the convex. Keep going at it, eventually you'll get there. This is an "issue" you'll have with many if not all production knives
 
Yeah, it "looks" thick behind the edge?
Are these thicker knives?
From the picture, id want a shallower sharpening angle. Although I like less than 15 degrees secondary.
 
Based on your picture you are not getting to the Apex.

Are you using the 40 degree slots so it would be a 20 bevel? That is what I use not the 30 for 15. You could get some CBN rods as that would be quicker to profile the edge, but at this point maybe you don't want to invest more in sharpening the CRKs.

I have used the sharpmaker at 40 setting and had good results. Try cutting phone book paper before you start and check the knife between changing rods to see if you are improving the edge.

Do you follow the instructions of starting on the edge of rod and then go to the flats for 20 strokes for each alternating rods?

Clean your rods with Ajax or Bar Keepers Friend to make sure they are clean. This would speed up your sharpening progress.

Your knife is a tanto blade so the grind is straight and you don't have a belly to contend with. That should make your sharpening easier.

Watch the videos in this post:

P

Thread 'Factory edge or sharpen?'

Just curious how many crk owners keep your factory edge as long as you can then send it out to factory for a sharpen ?
How many just say F it and sharpen themselves ?

I have a few CRK’s now I’m on the fence about sharpening. I use my wicked edge on all my other knives with great results but something about touching my reeve edges makes me cringe
 
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Sebenza's are known to have edge angles that can be all over the place, and also not necessary falling into the range that can be easily maintained with a Spyderco Sharpmaker.
Also: Sebenza edges can change quite a bit in angle along the length of the edge.
 
kwackster said:
Sebenza's are known to have edge angles that can be all over the place, and also not necessary falling into the range that can be easily maintained with a Spyderco Sharpmaker.
Also: Sebenza edges can change quite a bit in angle along the length of the edge.
Click to expand...
This is what I’ve found too. I had a heck of a time sharpening my CRKs and ended up reprofiling.
 
I'll echo the other comments about the 'convex' nature of the factory edge grind on Sebenzas, and how it tends to make contact on the rods behind the apex. I noticed the same thing with mine in S30V years ago, when trying to touch up the edge on the SM. I eventually reprofiled on a diamond hone to a slightly more acute V-grind, at or slightly below 30° inclusive. Since then, it's been stupid simple to keep the apex on my Sebenza tuned up. BTW, the narrower edge angle also dramatically improved how it cuts. So, there's potentially much to be gained in what might be a relatively minor reprofile.
 
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Reprofiling is indeed the best option to come to a better performing edge angle that can also be easily maintained with a Sharpmaker or comparable, but as Sebenza's can also have varying "behind the edge thicknesses"or BTE along their edges, you have no choice but to take this into account as well when you start reprofiling.

What i've found to work best is to first measure both the edge angle and the BTE all along the entire blade length, and then decide how to proceed.
Just reprofiling the edge into one continuous edge angle (of let's say 30 degrees inclusive) can lead to an unwanted visual appearance (with often much wider edge bevels appoaching the tip of the blade)
Such an edge will of course cut well, but many owners don't want the appearance that comes with such edge angles
What i do in cases like these is to use the BTE numbers as a guide to determine how much i can safely lower the edge angles in those areas without changing the visual appearance of the blade too drastically.
This may sound rather involved, but i think it's definitely worth it, especially for knives in this price range.

I often sharpen & reprofile Sebenza's and other higher quality knives for people who just bought one brand new and aren't satisfied with either the sharpness, the cutting ability, or both.
Several examples of Sebenza's i did (with before & after pictures) can be found in the sticky Paper Wheel thread here in the MTE subforum.
 
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Not going to help you figyre out your sharpmaker, but I had the same problem about 20 years ago with my Sebenza and the sharpmaker. I was told by spyderco at that time the white or brown stones were not going to be good with sharpening premium steels, just touching up. To sharpen I needed to buy their diamond rods.

Went with the advice of a knifemaker and bought a cheap 1x30 harbor freight belt sander, a 15 micron belt, a leather belt, stropping compound, and never looked back. From butter knife to hair popping sharp in 5-10 minutes.
 
sailfish said:
It would appear this is probably my issue. Could I assume this is because of the "convex edge" CRKs come with from the factory, and why I don't seem to have this problem with my other knives? This would also explain why I seem to have had better luck when I would hold the knife to the rod at a slightly broader angle than plumb.

xcuIZrI.jpg
Click to expand...

Yeah definitely not hitting the apex based on that photo, looks much closer to the shoulder. So it would make sense if the factory edge is pretty high on that particular CRK especially if you were using the 40 degree (inclusive) slots on the Sharpmaker in that photo. Spyderco's folding knives generally have a ~17dps edge so would work fine with the 40 inclusive (20dps) slots and why you don't have issue sharpening those.

You got a few options. First would be reprofiling the CRK to a lower angle with the diamond or CBN rods. Having done this in the past before I learned to freehand, this will take awhile on the Sharpmaker. You could get a different sharpening system that can accommodate the CRK sharpening angle. Or if you know someone with a 3D printer, there's printable blocks out there with many different angles for the Sharpmaker rods way beyond the standard 15/20dps.
 
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