Small Sebenza : S30V

[Cliff Stamp]

I attempted to fully sharpen this at 20 degrees and was rewarded by the frustration of why I switched to microbevels years ago. Forget that, I recut the edge with a 220 x-coarse waterstone. I intended to go 10/15, but after a half an hour of hand honing had it about 17 on one side and 14 on the other, so there was still a lot of work to do.

The edge was also burring heavily, one of the worst I have seen. Under mag a huge black bent burr was evident, up to 0.3 mm wide, it could be even be seen by eye. When I applied the 20 degree micro-bevel on the medium rods, the cracking of the burr could be felt as it was really rough on the first few passes. However after refining the edge on the white rods it got very sharp.

A few test passes on my arm showed a very high shaving smoothness, some CrO work later and the thread performance had jumped to 71 +/- 4 g, a 77% improvement over the initial finish, and one of the best results I have seen to date. Some test cuts on rope showed the edge was free of a wire edge as it cut cleanly and achieved push cuts with 14 +/- 1 lbs with a 61% improvement over the NIB finish.

I'll be using it for a while with this profile before taking it down to 10/15 with the next few serious sharpenings.

-Cliff

 

[Gary W. Graley]

...Yes, it is the hell of being cut to pieces...
-Cliff

Big Trouble in Little China, great movie

See this page
G2

 

[Cliff Stamp]

That is really an excellent movie, there is a script for a sequel to "Buckaroo Bonzi" which has Jack Burton in it, doubt it will ever see film, but still makes a decent read.

I used the small Sebenza with the new profile and the difference is many to one over the 20/25 micro-bevel. It is moving up to towards one of the better small cutting knives I have seen.

Interesting how much experience/perspective makes a difference. I was at a friends before supper and of course was giving them at hand, because if there is any knife work to do I am there.

So we are peeling potatoes and I had them the 20/25 Sebenza and ask them how for their impressions, they note it doesn't cut very well at all. One of my other friends comes over (not a knife guy), makes a few cuts and thinks its great.

The first guy has a small opinel that I tuned for him, and he handles a lot of my knives which are highly optomized, the other guy was comparing it to what he normally uses which are really cheap imports.

-Cliff

 

[Jerry Hossom]

...In the above I was talking about the transition from the primary to edge grind, on some knives this is buffed and thus it can't be easily pin pointed, Hossom is one maker who does it.

It isn't even relevant to the question Dave asked as to the nature of the primary/edge grind. Hossom has even done sabre flat grinds on some of his knives and I assume he still buffs the transition line..-Cliff

It sometimes stuns me hearing what I do from someone who doesn't know.

I DO NOT buff the transition of primary bevels to edge, nor have I ever done a saber grind except one that will never be a knife or leave my shop.

 

[Cliff Stamp]

I DO NOT buff the transition of primary bevels to edge ...

When we discussed sharpening many years ago you noted that after creating the edge bevel you blended the apex so that there was a smooth flow between the bevels not an abrupt transition point.

Of course if you want to say now you didn't say that, and you never have done that and I must have misread you, no problem. So you leave crisp distinct and sharp transition points on your bevels. Ok.

Most people who do the blending, and there are many, will argue for a drag/friction advantage, and there are also cosmetic issues, it isn't in any way a bad thing.

...nor have I ever done a saber grind except one that will never be a knife or leave my shop.

Not only did you make one, you even named it, you called it sabre-reflex. It was a knife with a hollow grind that went into a sabre grind, this is of course the same grind found on hardwood axes.

The reason I mentioned this was simply that the point I made with Dave had to do with a transtion of primary to edge bevels, irregardless of the nature of the grind curvatures.

Simply put, if you are quoting an "edge thickness" on a knife with no distinct secondary edge bevel due to it either being buffed/blended (or simply full flowing), you have to state a distance, as in "the edge is 0.025" thick at 1/8" back from the edge".

-Cliff

 

[Jerry Hossom]

Cliff, what I did, what I do, and how I did it and do it is not/never was a buffing process. I use belts on a rotary platen to shape my edges. We did indeed discuss convex edges many years ago, which at the time you found to be without merit. Our email exchange was my attempt to explain to you the advantages.


What I call a "Saber reflex grind" is far removed from what anyone would call a "saber grind". I think your problem stems from never having seen one. They are entirely unique.

 

[Cliff Stamp]

Cliff, what I did, what I do, and how I did it and do it is not/never was a buffing process.

So do do you have a sharp ridge line across the top of your edge bevel or do you buff/blend the bevels together?

......you found to be without merit.

I was using and discussing convex grinds on the internet before you were ever a part of the forums Jerry. One of the first customs I bought had a convex edge and after discussing it with Mel Sorg I had an exchange with Joe to add to the FAQ how to sharpen convex grinds with sandpaper and a soft media that they didn't need belt sanders, and later still after talking to a traditional maker I discussed how to do it with regular benchstones.This was back before Bladeforums existed, over on Knifeforums.

I think your problem stems from never having seen one.

This is your description :

"It begins at the top with a hollow grind to remove weight, but transitions into a saber grind near the edge ..."

This is exactly a hard wood axe profile, and note the "transitions into a saber grind" part.

-Cliff

 

[Jerry Hossom]

Cliff, having a dialog with you is an exercise in frustration. I do so only when you misstate material facts about me, misquote me, quote me out of context, or generally bring me into the conversation against my wishes, all of which you've done in this thread. Your participation in convex edges and mouse pads substantially postdated our email exchanges. Regardless, these matters would never arise if you'd just pretend you don't know anything about what I think or how I make my knives, which in fact you don't.

End of conversation...

 

[Cliff Stamp]

Your participation in convex edges and mouse pads substantially postdated our email exchanges.

Check your dates Jerry, I was discussing this with Mel Sorg before your first post on Bladeforums, let alone emails we exchanged.

To be specific, on 10-26-1999 you posted on Bladeforums you were starting to experiment with convex edges, as up until then you shipped your knives with a "utility edge" because high sharpness edges were fragile. I was discussing convex edges with Mel Sorg long before that.

Yes I can understand it would be frustrating to have facts pointed out to you which show you contraditing yourself like your adamant stance on you never having done a sabre grind and then stating clearly on your webpage that you have.

So no clarification on your edge apex grinds, it is a pretty simple matter, you either leave them sharp or you blend them.

-Cliff

 

[SteelDriver]

Yes I can understand it would be frustrating to have facts pointed out to you which show you contraditing yourself like your adamant stance on you never having done a sabre grind and then stating clearly on your webpage that you have.

Read again what Jerry said.

What I call a "Saber reflex grind" is far removed from what anyone would call a "saber grind".

So no clarification on your edge apex grinds, it is a pretty simple matter, you either leave them sharp or you blend them.

-Cliff

It's not always so simple. I had a custom knife by Jerry and the primary grind-edge line appeared crisp and distinct, yet the transition point is not sharp nor can be felt other than the change in finish. Jerry does not buff the transition yet has no problem achieving a smooth flow from edge to primary grind.

Now, can we end this off-topic semantics game and get back to the Sebenza?

 

[Cliff Stamp]

Read again what Jerry said.

Read his webpage description which I quoted where he says clearly : "transitions into a sabre grind".

Now compare that to what I said and see if you can find reason to contend it.

It's not always so simple.

Yes it is, you either have a distinct edge bevel or you don't. If you don't, then as I noted to Dave you have to be clear about what height you are using when you quote an edge thickness, if you do have one you don't because the top of the bevel is obvious. The difference can be seen in the following (crappy) picture :

http://www.physics.mun.ca/~sstamp/images/al_bolo_bm_pab_ak_side.jpg

There are distinct edge bevels on three of the knives, the custom bolo in the middle however has a secondary edge bevel which is far more obtuse than the primary grind, however it is fully blended back into it so you can't see it. Thus you can't give it an "edge thickness" without being specific about where you are measuring.

As for ridge lines, they are never actually sharp enough to stand out under your thumb like a spike, I almost never blend edges for several reasons and the bevel is distinct and clear and forms a sharp apex where the primary grind of about 3 degrees hits the bevel grind of about 10, however you would have to have a really sensitive thumb to feel it, it isn't like you can use it as a scraper.

So apparently Hossom doesn't blend the edges on his knives, thanks for the details, lots of people do though on lots of knives, so again you just have to be a little specific about what you are measuring, same as if you want to note the angle of a convex edge.

-Cliff

 

[Cliff Stamp]

With the new edge, the small Sebenza has one of the better cutting profiles seen on a small folder, on shallow cuts anyway, it is still problematic on deeper cuts, more to follow.

On carving hardwoods, the cutting ability has improved significantly over the NIB profile, it now pointed the section of Birch in 2.6 +/- 0.3 slices. The 20 degree micro bevel easily had enough durability to retain a shaving sharpness after several points.

In the kitchen it now has the feel of an optimal paring knife, this is when it will float through potatoes with no appreciable force, you can pull rather than push the knife when peeling. To be specific if you put a small white potato (size of two fingers in thickness), the Sebenza will cut right through it without showing any force on a normal bathroom scale, the dial won't move.

In contrast, for reference this takes ~4 lbs on a Kershaw Vapor which has quite a decent cutting profile of its own. However on thicker potatoes the wedging action of the hollow grind starts to become noticed and both knives will take about the same force, ~ 5 lbs on medium / large white potatoes (three fingers in thickness).

They act quite differently though, the Sebenza goes in quite readily, with no force apparent, then sticks at the top of the grind and the force jumps up to maximal almost immediately. In contrast the Vapor sees a steady rise in force through the cut.

In regards to durability with the reduced profile, the small Sebenza was used to cut the fins off a 3.5 lbs Salmon, cutting right through the bones. It was then used to cut the fish in two pieces, going right through the backbone. After the cutting it was still shaving sharp.

-Cliff

 

[BladeGoblin]

Cliff, just an observation here, you have WAY too much time on your hands. Go out for a walk and get some fresh air.

 

[TedV]

I also meant to note that the lock engagement is way over half way, I like this as the whole "break in" arguement I find insensible.

-Cliff

If you take it apart and put it back together again, it will very likeley get back to the 'factory default', which is about 40% lock cover IIRC but YMMV.
After using mine for 2 years, I still goes back to the same position as where I got it in. (and I've used, and re-assembled it a lot!)

Ted

 

[Cliff Stamp]

Which is one of the problems in some of the lower grade integrals as they can be very solid at first but wear really fast which can effect the locup.

I finished a few rounds of cardboard cutting with the Sebenza and a Manix, both had the same primary and secondary edge profiles, 10/20, and were finished on the fine Spyderco rods.

I used a once inch section of edge to do the cutting which was on a push at about 45 degrees, well actually more of a slice as the cuts would draw through the one inch through a foot section of cardboard.

The cutting ability was similar, the Manix's full grip worked better in the long term, as in total about a 150 cuts were made with with each knife for each run so 600 were made in total.

After ~42 m of 1/8" ridged cardboard cut against the ridges, both blades were bunted down to about 35% of initial sharpness. The Manix was consistently sharper through the four measured points of comparison, but the difference was small, ~10%.

As a side note about sharpening and reports of low edge retention and chipping, with S30V, as it has a very high wear resistance, and rather low hardness in comparison, it is easy when using rods to form the edge into near ideal sharpness through alignment but all the metal on the edge is left stressed.

After each round of honing I would reset the edge with a 220 grit SiC hone to prevent this problem. If I instead just used the Sharpmaker to rework the micro bevel, in just a few passes the blade would be back to shaving sharp, but heavily burred and very weak with the edge retention just a fraction of optimal.

This is one of the steels where reading some of Jeff Clark's comments about how to deal with burrs would be very informative. Even after resetting the edge I had to be very careful how I formed it or it would not reach optimal sharpness nor have quality edge retention.

In particular after the edge was formed on the medium rods I would check for shaving ability on both sides of the blade and do a quick check under mag to eliminate burrs, if this isn't done and you proceed to the fine rods with a burr left it can be prone to persisting and frustration.

I am definately going to have Phil reharden at least one and probably more of the S30V blades and see if it improves this aspect along with the edge retention.

-Cliff

 

[DaveH]

OK just so I'm clear on this, would the sebbie blade be made harder, softer, or just an entirely new heat treating cycle?

 

[Cliff Stamp]

I have not decided which ones are getting worked yet, but they will be made much harder. I may just get all of them done and then check different hardness levels up to 62 HRC.

-Cliff

 

[TedV]

Which is one of the problems in some of the lower grade integrals as they can be very solid at first but wear really fast which can effect the locup.

Cliff, is this a comment my post about the lock-up? Can you explain your comment a bit more because you can't be serious about comparing the Sebenza to a lower-grade integral?
Also, I doubt the change of lock-up position is due to wear. If that were so, it would be the same after re-assembly as it was before, which is not the case on the Sebenza. There is no wear on my 2 year old EDC Sebenza...

 

[Cliff Stamp]

Can you explain your comment a bit more ...

While I have seen very inexpensive knives with a lockup just as stable, or probably more so than the Sebenza, because I have done things with them that get cries of abuse with a Sebenza, the liners then to move to the right fast which I assumed was wear because the handle materials are cheaper and wear faster, or maybe they don't have the resilence of the Ti grips on the Sebenza.

Also, I doubt the change of lock-up position is due to wear. If that were so, it would be the same after re-assembly as it was before ...

I assumed it was wear on the Vapor as it is moving to the right pretty fast. I'll take it apart and check and see if it makes a difference.

-Cliff

 

[allenC]

Thanks for the great thread!
There are tons of interesting information to be learned.

Seal flippers and tin cans?
Truely a unique review.

Good luck,
Allen.