A CPM 420V questions for the steel experts.

R

RASF

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Dec 14, 2004
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Hi,

I am new to knife making and I want to make some few prototype knives out of CPM 420V steel. I know the steel is hard to work with and it has both pro´s and con´s regarding edge holding and toughness and of course sharpenability.
What I am looking for is a knife that both can cut and chop woods. I am not after a super cutting knife or a super chopping machete but something in between these two worlds.

Here comes my project. I want to make a few 10" blade length camp / survival knives with saw teeth on the spine. Blade width is going to be 2" and it is going to be made out of 0.40" stock thickness - yes, that is right 0.40". The blade will get a flat grind from spine to the cutting edge. The blade will be heat treated to either Rockwell C 57 or if possible to 58.
The thickness is for getting enough overall strength and hopeful more toughness at the cutting edge into the knife and for making the knife heavy enough for easy chopping.
The saw teeth will be made so they work, so they will not be gimmicks. The 420V steel also gives the teeth good wear resistance so they won´t be worn out immediately. Plus the 420V steel will give you an overall knife that not can be worn out easily.

Now to the questions. Will this type of knife could both cut and chop ? Will chopping destroy the cutting edge badly, cos´it is CPM 420V steel harded to 57 or 58 ? Will this knife could break while chopping - too hard perhaps ? Should the blade get a cryo treatment to get the best out of the blade ?
Well, I know this is an insane steel to use for camp / survival knife but with the right dimensions and hardness of the steel could this steel not also be used for such a task ?

I have chosen this steel because I need a stainless steel knife. And I firmly believe that if stainless is going to see hard use they also have to made thicker that carbon steels have to be, maybe much thicker, right ? So that´s why the steel is so thick but with a flat grind I get a cutting edge I can use.
You may now say if I really want a stainless steel blade then why not go CPM S30V instead. It is tougher, I know but I can only get this type of steel in 1/4" thickness and I feel this still is undersized for a 10" flat grinded blade that is going to see hard use - a saber grind may be okay for 10" blade but I am not doing that.
Actually, I have only got two choices if I want a stainless knife in that thickness and it´s either 440C or CPM 420V. I will pick the CPM 420V because according to Crucible Steel the 420V has more toughness and much better wear resistance than 440C. But the negative sides are harder work of shaping the blade to finish and the worst part is to get the thing sharp again then it finally gets dull - I know.

So what is your comments on this project ? Totally out of track ? Madness ?

Regards,
RASF
 
I think there are better steels for your purpose, since you want both a cutter and chopper. CPM S30V for one seems to get a lot of praise for being an all around good steel. Its tough for a stainless, and holds an edge well. 420V on the other hand is kind of brittle if I remember right. I think CPM 3V is supposed to be very good in the role your wanting to fill but I don't think its stainless :confused:
There's a lot of good steels out there besides the CPM series as well.
 
It's CSM 420 which is not a CPM steel. It's stainless at 13.6 % Cr and .38 % C . At .040"x2" x10" you won't be doing much chopping ,it will be too light. Check the dimensions of camillus's BK 9 , that will be appropriate for chopping. For a saw to really work properly the teeth should have a set ,a properly made folding saw that a number of companies make would be a better way.
 
Mete
He said CPM 420V. Its now called S90V if I remember right, but that is what he's talking about.
 
I have only a limited amount of experience with CPM 420V (now called S90V) and a little more with S30V.

From what I've seen I think that 1/4" S30V would be as tough overall as the .40" S90V which tends to be rather brittle. At the cutting edge the S30V would be MUCH tougher than the S90V and would make a much more useful tool. 4/10" is getting pretty darned thick. JMHO.

Mike
 
Matt, thanks for the clarification.Numbers do mean something.S60V and S90V have very high carbon content therefore a bit brittle for impact use .S30V would work.My other comments hold.
 
Even stainless blades don't need to be that thick. I have a 9.5" blade in ats34 that has seen lots of abuse with no problems and it's only 3/16" thick.
A blade .400 thick is going to be too heavy to swing fast enough to cut light stuff and too thick to penetrate into anything more solid.
I would recomend 3/16 s30v for a stainless blade like that. You won't break that without a vise and a cheater bar.
 
Hi,

Thank you so far.

I know the CPM 420V (S90V) is not the ultimate choice for such a blade but I also see this project as opportunity to show that this kind of steel can be used for big blades and not just for folding knives and small fix blade knives because of it´s brittleness.

CPM S30V steel would probably be a very good choice if I could live with the 1/4" stock size on a saber grind blade. I still think that a 1/4" flat grind blade is too weak for really hard use - but that is my opinion, I could be wrong.

The heavy blade is also for less effort in chopping. Meaning that you will let the knife do the work for you - simply let it fall down (still with control) instead of swing it down. I also know because of the weight this knife will have it is not for everyone - the knife will need a strong owner to get the full potential out of this knife.
The thickness at the cutting edge of this knife may have a disadvantage in chopping but I own another stainless "survival knife" heavy made in 425Modified steel (Buck steel / but not a Buck made knife) and the bevel angle of this blade is alot wider than the knife I want to build. This knife chops rather well for such a thick blade and it penetrates deep enough for the work I want it to do. Just remember that I am not looking for super chopping knife nor a super cutting knife but something in between these two worlds.
Also I am looking for high strength blade that will not easy bend if the blade should be used as a small crowbar - actually, it most break and not permanently bend because you can´t use a bend knife for anything.

But if you all still are thinking that a CPM S30V 10" blade flat grinded in 1/4" stock thickness will do the work I will consider this information carefully and then make my choice of what way I will go. Thanks.

Regards,
RASF
 
mete said:
Matt, thanks for the clarification.Numbers do mean something.S60V and S90V have very high carbon content therefore a bit brittle for impact use .S30V would work.My other comments hold.
Click to expand...

No problem, you just know too many steels :D
 
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