what do you think of cpm440v ?

Cliff Stamp · Dec 17, 2003

Buzzbait :

I changed over to the S30V version of the Military a couple of months ago. I wouldn't even consider going back to the 440V version at this point. Spyderco's heat treatment of S30V is absolutely superb. I have experienced none of the sharpening problems on my S30V model that I had with the 440V version, and haven't noticed any drawbacks to the change in steel.

The most obvious difference here isn't any inherent property of the steels but the large change in HRC between the two. S60V at 55 HRC has the worst combination of properties for sharpening, high wear resistance in a soft steel. S30V has similar, or probably better wear resistance and thus low machinability, but is much harder and thus not nearly as prone to burr formation.

As to being difficult to sharpen in general, especially in reference to S90V and so on, this is more to due with steel suitability for the type of knife and optimal grind or lack thereof. If the steel is suitable for the type of work being performed and the blade ground correctly (minimal edge presentation), sharpening is just a matter of a few passes on a stone, if it is 1095 or CPM-10V it will still sharpen in less than 10 seconds (unless it is heavily damaged which is a case of unsuitable steel and/or geometry or accidental impact which happens rarely and thus isn't overly significant).

-Cliff

rev_jch · Dec 17, 2003

I have an old kershaw avalanche in cpm440v and a newer one in s30v. As far as the cpm440v I like it, it is very similar to s30v. I use a strop to maintain the edges on edges on my avalanches.

thombrogan · Dec 17, 2003

Originally posted by Buzzbait
The S30V Military is the most functional tactical folder I've had the pleasure of using.

Buzzbait,

Did you convex-edge the S30V Military, too?

Buzzbait · Dec 17, 2003

Originally posted by thombrogan
Did you convex-edge the S30V Military, too?

Nope. I didn't bother. The new Military is easy enough to sharpen at it is, and the cutting efficiency is very good "out of the box". It's just too good to mess with.

thombrogan · Dec 17, 2003

Cool. Thanks.

wire eddge · Dec 17, 2003

Without all the fancy talk, I have two blades with the same edge angle,blade thickness,blade grind same hardness(almost) one is made out of 154CM,the other S90V, if both are dulled to the same level(not able to shave hair of my arm anymore)when sharpened with the same 2 diamond stones with the same technique, the S90V blade will take as much as 3 times the amount of time to sharpen as the 154 CM blade which does prove the S90V blades wear resistance properties are superior to the 154CM blade.

What I ment to say was that S30V,S60V and BG-42 are just about perfect, they hold a edge long and are fast enough to sharpen, S90V is almost too much of a good thing!

Cliff Stamp · Dec 18, 2003

wire eddge :

... the S90V blade will take as much as 3 times the amount of time to sharpen as the 154 CM blade which does prove the S90V blades wear resistance properties are superior to the 154CM blade.

It shows the machinability is significantly lower this doesn't always mean the wear resistance is higher. You can get lower machinabilities without gaining wear resistance. Specifically the CPM steels in general have a higher machinability (will sharpen faster) than non-CPM steels of similar alloy content due to higher carbide dispersion, yet they don't lack wear resistance.

Back to S90V, yes the machinability is lower than ATS-34 class steels, S60V has the same problem though not to as great an extent. However as for sharpening in general this is of little consequence because the main factors are suitability of steel and optomiztion of geometry.

With the steel picked correctly for the task and the blade ground suitable, sharpening is a matter of a few passes on a rod or stone, so if it takes S90V three times longer than ATS-34 it is still less than a minute anyway so what difference does it make. You spend far more time setting up the hones.

Sharpening only takes a long time if you are reshaping the edge (because it was not ground right in the first place), cleaning up damage (wrong steel or grind), or the edge is far too wide (again ground wrong).

-Cliff

The General · Dec 18, 2003

I own 4 Militaries

1. a 1999 model in CPM 440V,plain edge, no problems, but hard to sharpen of course
2. Formite Military in CPM 440V plain edge, tip broke...
3. S30V plain edge
4. Soon to arrive S30V fully serrated

and one CPM 440V Native

The Fragility of CPM 440V was brought home with my Formite Military and the delicate Military needle sharp point. Its a pain to sharpen to a shaving edge but cuts for ever!

I prefer S30V myself.

wire eddge · Dec 18, 2003

I agree Cliff, it takes more effort to sharpen some of the higher alloy steels like S90V 10V ect. and its not a problem for me but I feel the average joe would be better served by steels like 154CM,VG-10 ect. And some knife uses are better served with softer,faster sharpening steels like 440C,1095 ect where speed of sharpening is of more importance than edge holding. Some examples that I prefer a faster sharpening knife are knives that I use at work as they get abused and dull fast and in hunting knives,skinning knives.

Cliff Stamp · Dec 19, 2003

wire eddge :

Some examples that I prefer a faster sharpening knife are knives that I use at work as they get abused and dull fast...

Yeah, the CPM stainless steels are not tough and will chip fairly readily, as will the CPM's in general as most are high alloy, with some exceptions like CPM-3V. If the knife is going to get damaged, then you do well to chose a steel which minimizes it like L6 and is easy to repair. On any knife for wood working or outdoor use in general for example I would never chose S90V (or any stainless steel for that matter).

The biggest problem in this regard is steels being hyped as "quality" or "superior" made in wide sweeping statements which promotes the idea that they are good choices regardless of the type of knife. This is complete nonsense because any steel will make a very poor choice for some knives and a very good choice for others. You have to be able to pick the steel to suit the performance damands of the user.

-Cliff

wire eddge · Dec 19, 2003

Cliff, you say that you wouldent want any stainless knife for a outdoor or hunting knife?

Please explain your position,this isnt turning into a "Stainless verses Carbon steel" debate is it?

I assume you are refering to all outdoor and hunting blades and not just large choppers,camp knives.

My small fixed blades(4-5 inches) in ATS-34,Bg-42 ect. have been great and I assume S30V would also do wellin this type of knife as long as they arent used in place of hatchets and saws,which even a blade of A2 wouldent look new at the end of the day.

Cliff Stamp · Dec 22, 2003

Yes, any outdoor knife. If left exposed to the elements that class of steels (ATS-34) will pit readily. The only benefit is you can subject it to minor corrosive action without seeing ill effects. This to me is of no significant benefit and certainly not worth the trade off of lower machinability and far lower toughness and ductility.

Outdoor knives tend in general to cut dirty materials and thus have a higher requirement for toughness and ductility than regular EDC knives used for utility and food prep in and around the house, plus they can occasionally be called in for heavier cutting such as baton work. In general the non-stainless steels are thus much more capable of both resisting damage as well as being much easier to repair when that piece of wood had a stone or nail which was struck, or that length of rope had a decent sized rock inbetween the strands.

For a folding knife however, there can be benefits as they are much more difficult to clean, especially around the piviot and unless you either take them apart or heat them with a blower, there is going to be some water remaining and then you get crevice corrosion around the pivot. This is why I would not really want the Military for example in CPM-10V, but I would rather have that than S30V if the Military was a fixed blade version of the same knife.

Now in the kitchen I see value in stainless blades as it makes for less rinsing and wiping, especially when cutting a lot of acidic fruits and vegetables. Similar for a salt water fillet knife, a decent stainless blade can allow you to lay the knife down without having to keep rinsing it.

This is of course justone aspect of performance, there are lots of knives I would chose for outdoor work even though they are stainless over other carbon steel blades because the difference in geometry was more significant.

-Cliff

Steve-O · Dec 26, 2003

Possibly the easiest to read comment that I have seen Cliff to make (above), and of course, it is hard to disagree.

Because I cook, poeple ask similar questions...non-stick vs regular, anodised vs stainless, the questions are endless, the answer is the same..depends on what you cook.

And even though pan makers switch materials as often as knife makers do, I can always recommend a middle of the road/works for everyone/compromise.

You should see my pans! S30V/CPM420V!

Steve-O