Why BG-42 is better than 420V for Sebenzas

JoHnYKwSt · Nov 17, 1999

Here's my thoughts on the subject.

420V is more brittle than BG42. This is why 420V is hardened to a fairly low 57-59Rc. BG42 on the other hand at 61Rc is no more brittle than ATS34 at 59Rc.

Now if you have a real thin edge like on the sebenza, a softer edge will roll and dent easier than a harder edge. BG42 is perfect because the edge can be left hard, 59Rc, and it will still be tough enough to withstand chipping.

420V on the other hand is very abrasion resistant. If you want to sacrafice a thinner edge for a thicker one, then 420V might work better.

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Johnny
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ThomM · Nov 17, 1999

I'll accept that it is better because Chris Reeve says it is.
He has stated his reasons, and although I have had and used many knives over the last 40 years, and followed the subject of knives passionately in many books, magazines and papers, and many gun and knife shows, I will concede that he probably knows a heck of a lot more about his materials, his product, and design and build processes.
It is apparent to me that a lot of people, myself included, agree with his choice of blade materials.
I think that if he finds a better material for all aspects of his product that will benefit the consumer and his processes, he will change, just as he did from the world popular (for a very long time) ATS-34
My $0.02.

Humpty · Nov 18, 1999

Very true Thom, Chris knows what he's talking about and he would try and benefit his customers in all way possible

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-Humpty

"Humpty Dumpty sat on the wall. Humpty dumpty had a great fall.
Maybe Humpty should of had a knife."

JoHnYKwSt · Nov 18, 1999

The reason I posted is because Chris gives a lot of reasons as to why he will not use 420V, but never really gave reasons as to why 420V is not a good steel for the sebenzas. Some of Chris' reasons have been, it's too hard on the machinery, it is not that much better than BG42 to warrant a change, a change costs a lot of money (R&D), etc. His reasons however, still leave people thinking 420V is a superior steel, and that he cannot use it because he is not a custom maker anymore. I'm just trying to add to his reasons. I'm not questioning his choice in BG42 in any way, just reinforcing them.

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Johnny
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stjames · Nov 18, 1999

Johnny, thanks for the analysis, your points seem solid.

There is also a lot to be said for going with a makers strength, no matter what the product. The issue is results.

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James Segura
San Francisco, CA

Scarman · Nov 18, 1999

I have never used 420V so I can not comment from experience. I have read the 420V is a good steel, supposedly better then 440V but again that is all subjective.
I do like my Sebenza with the BG42 and am more comfortable with the blade of this knife than the ATS 34 blades of my 975 or my Nimravus.

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The bible is not such a book a man would write if he could, or could write if he would.

*Lewis S. Chafer

2 Tim 3:16

Larry in KY · Nov 18, 1999

I have a custom made from 420V and in my opinion it does not even compare to BG-42 and I'll tell you why. BG-42 is easy to sharpen, I have found that it is easier to sharpen than any other stainless steel I've used..and I've used most of them! I have the Edge Pro sharpener and it will sharpen any steel, some take longer than others to sharpen. IMHO 420V is much harder to sharpen than ATS-34 and both take a relatively long time in comparison to any other stainless/non-stainless steel. However, I do feel that 420V will hold it's edge longer than ATS-34.
And like the other posts, I have faith in CRK!!

JoHnYKwSt · Nov 19, 1999

BTW...BG42 at 61Rc is no more brittle than ATS34 at 59Rc. So if the hardness of BG42 is lowered to 59Rc, you get an edge that is just as hard but is much tougher at the same time. This increased toughness enables you to thin the edge more and not have chipping problems.

Sorry I forgot to mention this in my first post.

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Johnny
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Tom Carey · Nov 19, 1999

The only reason I feel 420V should not be used is because of the difficulty involved in Sharpening. I will tell you for a fact that it will not only hold an edge longer than BG42 but it will hold an edge for a heck of a lot longer than BG42. I really don't feel that the brittle issue is legit. How many of you are prying with a Sebenza honestly? I have used knives in 420V and done some prying with them. They have not had any problems. Of course I do avoid doing any serious prying with a knife. My preference at this point is either Stellite or Talonite. It is easier to sharpen both of these than ATS and they will hold an edge longer. Also they are way more resistant to corrosion. I would be interested in knowing if Chris has done any testing with either Talonite or Stellite and what his views are on both of those. I love the Sebenza and have owned two of them so far. The reason I sold them was because I am not satisfied with either ats 34 or BG42 when it comes to edge holding. If they were offered in something like Talonite I would buy another one and keep it.

Regards,

Tom Carey

[This message has been edited by Tom Carey (edited 19 November 1999).]

Donald · Nov 19, 1999

Tom,
Chris made several comments on Talonite in KnifeForums, of course that seems to be down for the count.

I do not know about 420V, is the corrosion resistance higher than 440V? I believe I saw a comment on this, but it might have been a toughness question. I like my 440V Spyderco Bladeforums Native, but when I cut some vines and did not clean it, I recall it showing some minor rust the next day...or now as memory fades, perhaps it was just the sap turning color. I also recall this being after Tuf-Cloth, now why isn't my experience the same as many others re Tuf-Cloth. Can they expire? Mine were bought new early this year.

I like 440V.

I also like BG-42 in my Sebenza and have been very happy with it. I can get it very sharp.

I usually cannot get ATS-34 as sharp as I would like, but that may just be my poor technique. I'll work on that when I have time.

Donald.

Cliff Stamp · Nov 19, 1999

Larry, I am pretty sure that the Edge Pro uses AO waterstones, these are too soft to cut into 420V well. I have blades in 420V and 10V and both sharpen easily on diamonds or SiC hones.

Regarding toughness, I have not seen any evidence to suggest BG-42 is tougher or stronger than 420V posted by Chris or anyone else. If someone wants to do some cutting with their BG-42 Sebenza to illustrate the kinds of tasks that would cause a 420V blade to have problems I will repeat it with mine.

-Cliff

Tom Carey · Nov 19, 1999

As far as staining and 440V goes I have owned two Spyderco's with the material and used them everyday for over a year. I never had any problems with corrosion or staining with either. This was after daily carry and use. For some background I am in the midwest and and work in a printing plant. In the summers time it gets very hot and worse yet very humid. Generally humidity is it about 100% here. The temp's in the factory generally stay rite up near 100 most of the day. So of course I sweat like crazy and the knives I carry are clipped inside my right jeans pocket unless they are fixed blades. So the potential for corrosion is certainly there. I only bother oiling either knife about 3 or 4 times in a year. If I had a knife with an ats 34 blade it would have nice lil freckles by the end of a 12 hour shift. Which is why I still find it hard to believe that 440V is actually slightly less corrosion resistant than ats. That is just one more reason why I prefer to do my own real world testing and not go by salt spray tests or magazine tests. To get back on track here I do think 420V is supposed to be more corrosion resistant than 440V. I only had a knife in that material for about a month. A buddy and I swapped for a short time just for fun. I would also like to see proof that BG 42 is tougher. Like Cliff I would like to see some real world testing. I would not be shocked if there is a difference but I believe it will be marginal. Also I have found that those paper wheel set up's that some of you may have seen being used or sold at gun and knife shows is the best way to sharpen steel's such as 420V and even ats 34. You would be surprised just how sharp you can get knives in such steels.

Regards,

Tom Carey

Longden · Nov 19, 1999

I haven't been to many gun/knife shows ... what's a paper wheel? Is that a disk sander of some sort?

JoHnYKwSt · Nov 19, 1999

OK, first we are forgetting a few things. Not all edges are created equal. Thinner edges cut better then thicker edges. Thinner edges after a certain point lose a significant amount of strength. The Sebenza has a very thin edge.

Tom,

I will tell you for a fact that it will not only hold an edge longer than BG42 but it will hold an edge for a heck of a lot longer than BG42.

I agree with you on this one. And so does almost everyone else. I never questioned 420V's edge holding.

I really don't feel that the brittle issue is legit. How many of you are prying with a Sebenza honestly?

When I said 420V is more brittle, I was not in any way reffering to brittle in regards to prying. The brittleness issue has to do with the edge, and chipping.

Talonite is very soft. To put a thin edge on talonite would be disastrous. Also, I'd be interested in how your talonite blades hold up to cutting hard materials, oh and steer clear of those staples. Don't get me wrong, Talonite is great, and works awsome for almost everything, but it does have it's shortcomings.

Cliff,

Regarding toughness, I have not seen any evidence to suggest BG-42 is tougher or stronger than 420V posted by Chris or anyone else.

You said in this thread, http://www.bladeforums.com/ubb/Forum32/HTML/000064.html

420V is directly superior to 440V. It has better wear resistance (twice), better toughness (a little like 25%) and better corrosion resistance (twice). The central point is the toughness. To be specific, to get the toughness of CPM-10V at 63 RC, CPM-420V needs to be left lower than 57 RC and 440V even more so. There is a huge difference in how a 63 RC steel blade will behave and a <57 RC one. As another example, at 59 RC D2 has a decent level of toughness. To reach that in CPM-420 you need to drop down to 55 RC.

That quote leads me to believe that 420V would best be left heat treated to 57-59Rc. Many say 420V is tougher than BG42. I am one of those people. But this toughness is at the rather low 57-59Rc. This is where I got the impression 420V is more brittle than than BG42 at the same hardness. If this is false someone please correct me.

If someone wants to do some cutting with their BG-42 Sebenza to illustrate the kinds of tasks that would cause a 420V blade to have problems I will repeat it with mine.

Unfortunately, I do not have any 420V blades. I sure would like to see a thin edged 420V bladed sebenza go up against one with a BG42 blade. That would be the only way we will ever know.

All of the following must be taken into account:

BG42 has optimum hardness around 61Rc.
420V has optimum hardness around 57-59Rc.
A harder edge will roll and dent less than a softer edge. Instead a harder edge will chip.
The tougher the steel the thinner the edge can be made before it becomes too brittle.
If BG42's hardness is lowered to 59Rc it will gain a lot of toughness and still be very hard. (Sebenza)
If 420V has its egde as thin as a sebenza it will roll and dent much more, because of it's low hardness.

420V would be perfect if it could be: (keep in mind this is with a thinner edge)

hardened to 59Rc, which would conteract the edge rolling and denting.
be tough enough at that hardness to not chip.

Unfortunately this is not the case. However, on "normal" thicker edged knives 420V is great. The sebenza does not have a normal edge.

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Johnny
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Cliff Stamp · Nov 22, 1999

John, it is quite possible that BG-42 is tougher impact wise than CPM-420V, I am not doubting that. However I have not seen any evidence of this fact but there is plenty of evidence to show CPM-420V is far more wear resistant and has high levels of corrosion resistance.

As for CPM's and thin blades, I have two CPM blades with thinner stock and bevels and more acute edges than how the Sebenzas are ground. As of yet I have not had any problems with them breaking up, although I have worked more with the 10V blade than the 420V.

My offer is still open, if somone wants to do something with their BG-42 Sebenza to illustrate the types of cutting that could be a problem with CPM-10V or CPM-420V (two very high Vanadium steels), I will duplicate it.

-Cliff

Longden · Nov 22, 1999

Now if you have a real thin edge like on the sebenza

So how thin is the Sebenza edge compared to others? Does anyone know the edge angle on a NIB Sebenza?

I know the FAQ recommends sharpening on the Spyderco (or any other stone) at 18-20 degrees (to get a 36-40 deg included angle), but Spyderco says the same about their knives even tho they ship them at 30 degrees included angle.

JoHnYKwSt · Nov 23, 1999

All the points that I have mentioned, is how it looks on paper. In theory, 420V should roll and dent more. And it should. How much it will roll or dent and if that even matters, only testing will tell.

As for someone doing tests with their BG42 sebenza, it would be easier if someone just sent you a sebenza to test. I am still thinking about whether or not to do this at the moment, as I started the topic.

Longden,

There's more to it than the angle that the Sebenza is sharpened at. You also have to consider how thin the base of the edge is.

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Johnny
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Cliff Stamp · Nov 23, 1999

Johnny, yes, exactly, it is the extent that is important. The Sebenza's BG-42 blade would have an advantage being slightly harder and quite possible still tougher, but the extreme amount of Vanadium carbides in the CPM-420 greatly enhance cutting ability. It would be interesting to see how they stacked up.

it would be easier if someone just sent you a sebenza to test

While I would of course appreciate that, there are things that need to be considered. Specific to the question at hand we are discussing limits (chipping, indenting and such) so the edges on both blades have to be stressed above the plastic deformation limit. It is possible that in doing this that a gross failure could happen. Not overly likely but I have seen it. Tests can sometimes produce results widely different from the expected.

-Cliff

Longden · Nov 23, 1999

There's more to it than the angle that the Sebenza is sharpened at. You also have to consider how thin the base of the edge is.

That's true in regards to cutting performance. A blade with a thin spine should slice thru light material better than one with a thick spine, assuming the edge bevels are the same, since the latter will have more shoulder.

However, your original statement refers to the Sebenza edge's ability to withstand dents, chips and rolling:

Now if you have a real thin edge like on the sebenza, a softer edge will roll and dent easier than a harder edge. BG42 is perfect because the edge can be left hard, 59Rc, and it will still be tough enough to withstand chipping.

Excuse me if I'm wrong, but it seems that if you have two blades of different spine thickness, but comparably thin edge angles (say 30 degrees), I would think that edge deformation is somewhat independent of the amount of material that far back from the cutting edge. A 1/8" blade sharpened to 30 degrees should have the same amount of metal behind it at 3/16" from the cutting edge as a 1/4" blade sharpened to the same degree (if my trig is correct). The latter blade will have had much more metal removed in order to achieve the same angle, so the leading 3/16" (or so) edge on both blades should be structurally similar and equally susceptible to edge deformation.

Widening the edge bevel changes this, since a wider angle brings the shoulder of the blade material closer to the edge.

Hence my question of what the angle is.

JoHnYKwSt · Nov 23, 1999

Longden,

According to Anne, Sebenzas are sharpened 18-20 degrees. I'm not sure if this is correct, as my sebenza's factory edge seemed to be closer to 15 degrees.

The base of the sebenza's edge is so thin because it is a hollow grind. Not just a normal hollow grind but a high hollow grind. Also, the sebenzas blade is wide, and when the grind gets down to the edge, it is very thin.

Though, the angle of the edge is more important in regards to edge chipping and denting.

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Johnny
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[This message has been edited by JoHnYKwSt (edited 24 November 1999).]

Why BG-42 is better than 420V for Sebenzas

Sebenzanista