Blade chipping

[The Aflac Duck]

I recently had my Manix2 in s30v chip terribly in 2 spots along the edge. I was pull cutting fairly thick boat rope. I believe it to be a brittle edge from the factory sharpening as I had not yet sharpened it, is this normal for Cpm s30v? I have read that it's more likely to roll along the edge rather than chip.

S30V is a chippy steel IMO. S35VN was designed to be tougher and less chippy than S30V.

 

[bodog]

I recently had my Manix2 in s30v chip terribly in 2 spots along the edge. I was pull cutting fairly thick boat rope. I believe it to be a brittle edge from the factory sharpening as I had not yet sharpened it, is this normal for Cpm s30v? I have read that it's more likely to roll along the edge rather than chip.

Doesn't sound terribly surprising. Look for a tougher, harder steel, look for a softer S30V, or increase your edge angle until it doesn't chip anymore. I've personally not been all that impressed with S30V myself. But then again I've not really been impressed with any steel that has charpy numbers in the high teens/ low twenties.

 

[Sulaco]

Bohler created M390 to hold up to corrosive environments and excel at wear resistance at high hardness levels. It isn't designed to be tough like CPM-3V for example. If you need something to stab bottle caps, I suggest a thick fixed blade with a good tool steel like A2.

As for the S30V comment, I also have found it to be a bit chippy, but not in the same way that VG-10 or similar steels are. The "chips" are more like micro-serrations and to me, are what makes S30V seem to keep a usable cutting edge for such a long time, where other steels like 154CM begin to roll and stop cutting sooner.

Just my two cents.

 

[M1GarandGuy]

I have several knives in m390 as well as its American counterparts and find that its the best preforming steel out there. The knives that I have with it do not chip at all but still have insane edge retention!
As far as toughness is concerned I own a bradford in m390 (61 HRC) and have found it to be very tough considering its high rockwell. Ive used it to baton wood with great results.

 

[NoviceNorth]

Okay, this is very interesting. Anyways, bradford will surely take care of you if you contact him.

But basically, what ya'll are saying is that the cpm-3v would be better? Because I currently have a Bradford Guardian 3 in CPM-3V, and I was considering returning it for the 390V version because I read that it would most likely be a better steel for this size of blade. I absolutely love the ergo and size of this blade, so I think I definitely want to keep it. Would the 3V be worth keeping? I will just make sure I keep the blade oiled?

 

[bodog]

Okay, this is very interesting. Anyways, bradford will surely take care of you if you contact him.

But basically, what ya'll are saying is that the cpm-3v would be better? Because I currently have a Bradford Guardian 3 in CPM-3V, and I was considering returning it for the 390V version because I read that it would most likely be a better steel for this size of blade. I absolutely love the ergo and size of this blade, so I think I definitely want to keep it. Would the 3V be worth keeping? I will just make sure I keep the blade oiled?

Depends on what you need from the knife. Both 3V and M390 are good steels. If you don't foresee doing very rough work then M390 seems to be favored by a lot of people.

There are a lot of factors to consider but generally speaking if both steels are heat treated to about 59 RC with a good heat treatment process then M390 will chip out easier than 3V. That's not saying it's easy to chip M390, though. 3V will blunt through abrasive material faster than M390. That's not saying 3V blunts quickly. M390 has better corrosion resistance, though 3V isn't bad. 3V can handle sudden impacts better, like being dropped or hitting against something, like roughly cutting open a box and hitting against the rim of a ceramic bowl, but M390 likely won't crumble apart in the same type of work.

Neither of them are indestructible and they've not figured out how to make a steel that never needs resharpening. Figure out what you want the knife to be capable of and then pick the proper tool. In general: rough use-3V, abrasive, corrosive use-M390.

 

[Bill1170]

I recently had my Manix2 in s30v chip terribly in 2 spots along the edge. I was pull cutting fairly thick boat rope. I believe it to be a brittle edge from the factory sharpening as I had not yet sharpened it, is this normal for Cpm s30v? I have read that it's more likely to roll along the edge rather than chip.

Was the boat rope clean or dirty? Large rope can conceal within itself some very destructive particulates (such as sand) that will damage your blade.

 

[shqxk]

M390/204P is not a tough steel by any mean... you need more obtuse/higher degree edge to solve the issue.

 

[ma tumba]

Got my Spyderco mule in 4V and put it to the "beer cap test". It chipped *exactly* in the same places where chipped my Bradford. The defects in the Mule are roughly two times smaller in size compared to those in the Bradford. I have no idea if the difference is caused by the difference in the edge geometry of in the steel.

Hell, those beer caps are tough little guys. Looks like I may order my next blade forged out of them, for extreme toughness!

 

[The Aflac Duck]

I don't know what to tell ya...

Maybe try cutting thing with your knife, rather than subjecting them to some "backyard test".

 

[bodog]

I don't know what to tell ya...

Maybe try cutting thing with your knife, rather than subjecting them to some "backyard test".

He's making a fair comparison for tasks he wants his knife to perform. Nothing wrong with that. Just like not everyone sees value in being able to cut beer bottle caps, not everyone sees the need to cut rope for hours on end. He's being honest with what he wants and is reporting what he finds. That's cool.

:thumbup:

There's a certain maker who sells a lot of knives because he can pound knives through solid concrete. Most people don't need knives like that but they like for them to be capable of it. The only way to see if they can do it is to do it...

 

[The Aflac Duck]

He's making a fair comparison for tasks he wants his knife to perform. Nothing wrong with that. Just like not everyone sees value in being able to cut beer bottle caps, not everyone sees the need to cut rope for hours on end. He's being honest with what he wants and is reporting what he finds. That's cool.

:thumbup:

There's a certain maker who sells a lot of knives because he can pound knives through solid concrete. Most people don't need knives like that but they like for them to be capable of it. The only way to see if they can do it is to do it...

Who needs to stab beer caps? Come on... And nobody mentioned anything about cutting rope for hours, so don't put words in my mouth.

Bottom line, if you want to punch a hole in bottle caps, then buy a punch or an ice pick. Nathan's knives have nothing to do with this, and aren't part of the original subject so you're posing arguments that are moot points.

I'm starting to question what people think a knife is even supposed to be used for...

 

[bodog]

Who needs to stab beer caps? Come on... And nobody mentioned anything about cutting rope for hours, so don't put words in my mouth.

Bottom line, if you want to punch a hole in bottle caps, then buy a punch or an ice pick. Nathan's knives have nothing to do with this, and aren't part of the original subject so you're posing arguments that are moot points.

I'm starting to question what people think a knife is even supposed to be used for...

People need tools for different reasons. Some people use hammers to hammer wood. Some people use hammers to hammer metal. Each hammer is made just a little differently but accomplish the same basic task of smashing something into or onto something else, plus another function or two if the maker can squeeze it in, like a roofing hammer, for instance. Who needs to use a hammer to cut something? Roofers.

Maybe the dude finds that punching bottle caps replicates his use? Maybe no one really needs to stab bottle caps but maybe they like to see that a steel won't chip badly in rough use and they have a supply of bottle caps ready to go?

Personally I don't need to stab bottle caps for any reason, but I do do things with knives that a lot of others don't so my tests try to replicate what I do plus some so I can feel my knife will do what it's supposed to do for me and my intended use.

I don't fillet a lot of fish. I don't cut a lot of vegetables in my kitchen. I don't field dress wild animals. But I use my knives pretty much daily. And it's possible I use them in ways you wouldn't approve, but they're my knives and I want them to perform at a level I find acceptable.

 

[Cobalt]

Hard brittle steel will chip if it lacks toughness. Tough steel will roll if used under too much stress or deform if it lacks abrasive resistance (aka wear resistance).

Regarding M390, look at this chart to see how it stacks up to other steels (CPM-20CV is Americas answer to M390). Please note, that this is when hardening 20CV to 58 hrc. When at a higher hardness, toughness will decrease.

What a retarded chart from CPM. Totally worthless when you look at each steels Rc. You cannot compare steels with different Rc's. This is so typical of CPM.

Back to OP's knife. To begin with, you cannot blame just a steel on the damage incurred. You can't just blame the edge angle either. You also have the overall blade geometry and how much metal supports the actual edge grind. More metal behind the edge gives the edge stability when you cut objects at different angles. Since no one ever cuts at a perfect 90 degree angle to the surface, the lateral loads imparted to the edge cause a shear and torque on the edge. Very easy to chip out a thinner blades edge than the same steel that has a thicker blade down to the edge. This may be the case with that knife. To many factors. I can grind an 18dps angle on a thicker knife and it will hold up better than the same angle on a thinner knife. I have done it. 18dps is a great angle for cutting. Not sure on a stainless steel I would use it for hard use. Increase the angle to 20-23dps and see what happens.

 

[ma tumba]

He's making a fair comparison for tasks he wants his knife to perform. Nothing wrong with that. Just like not everyone sees value in being able to cut beer bottle caps, not everyone sees the need to cut rope for hours on end. He's being honest with what he wants and is reporting what he finds. That's cool.

Thanks for your support, buddy!

I'm starting to question what people think a knife is even supposed to be used for...

:thumbup:

 

[ma tumba]

Ok, here I am again with my beer cap test on another fine knife.

Today I got this knife: http://www.bladeforums.com/forums/showthread.php/1353940-3V-quot-Dashi-quot-with-Bog-Oak-*SOLD*. This is a great little knife which I decided to buy for its great piercing ability.

Of course the geometry of this blade implies that the tip should be much weaker than that of the Guardian3 or the Spyderco mule, but this turned not to be the case.

I happy to report that the tip did not bend at all and there was no chipping whatsoever. The was some edge rolling but I was able to remove it by a few strokes along a smooth spine of another knife. And this 3V is at 61 hardness, so I expect some edge retention, too.

Great job rcetroy!