Recommendation? Any large CPM Cru-wear Blades

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klarson

Joined
Apr 2, 2023
Messages
5
Hello,

I'm trying to get started in knife making and have been making plans and designs for about a year. I finally saved enough to get myself a 2x72 belt grinder and all my belts and also pulled the trigger on some steel. Given how expensive the grinder and belts were, I started small with just a single 3/16" by 2" by 36" bar of Cru-wear from NJSB.

I was always planning on using 3v, but they had none in stock, so I wanted to make do and make sure everything would be arriving at once to minimize downtime and just get started next weekend when everything would be here.

I'm kind of stressing now. I have been planning out my designs and I always kind of wanted my flagship to be a 12" OAL bowie with a 7" blade. Kind of a traditional mk2 combat knife with a full tang and walnut scales and brass pins. But I was thinking about it and realized as I've been planning this out and researching knife designs and what's out there, I've never seen a cru-wear knife with a longer than 5" blade.

I'm a graduate mechanical engineer, so I'm familiar with the technical aspects of the metallurgy and I have Larrin Thomas' book and am aware of the toughness difference between cru-wear and 3v, so I was wondering if anyone had any experience either making or owning a larger cru-wear knife. Is there a common knowledge of the size limitation of cru-wear when the lateral stresses start to be too much if you're wrenching on a 7" blade that I wouldn't know about?

Looking at the charts for Toughness-Hardness I know at its highest Cru-Wear can manage 20 ft-lbs whereas CPM-3V its at minimum 30+, but CPM Magnacut is at its highest at around 15 ft-lbs and Architect Knives recently put out a model with an 8" blade in Magnacut.

I have other designs ranging in length, the smallest being 9" OAL with a 4.5" spear tip. So, I could make 4 of those instead of 3 of my larger design.

I may be just overstressing but I would appreciate any input.

Thanks for taking the time to read this,

Keith Larson
 
A2 ($70), 80CRV2, 8670, 5160, 1084 ($45-$55 for 4' bars), etc., ie simple carbon steels that can take more abuse, would have been a better choice for your first knives that you are practicing on! You could have gotten 2 to 3 times the amount of steel for the same price and not have to worry about toughness. Much less expensive, plus it's easier to grind and very tough. That CruWear bar is pretty expensive!!

You can also have the hardness reduced to 60 HRC when they are heat treated; I have seen 6-7" blades in CruWear at that hardness versus the 62-64 it's usually run at; lower hardness usually means more toughness. I would put the CruWear bar aside for now, and pick up a cheaper steel for your first blades. Learn how the grinder works, how the belts cut, etc on some less expensive steel. How are you going to do the heat treating? Will you grind before or after heat treating?
 
Welcome Klarson. Fill out your profile so we know a bit about you and where you live. It helps with answers and maybe a nearby smith would offer some free steel he has laying around.

BTW, you could have bought a years' worth of steel for the price of that Quartermaster knife you just bought.
 
I don't think I need to explain or justify what I do with my own time and money, nor do I appreciate looking through my history and making snide comments about it.

I'd prefer to just have answers to my questions.

Thanks again,
 
Your original post was about saving up for the grinder and belts and then you spent $170 with shipping on your first bar of steel to get 3 or 4 knives out of. And they are your first knives ever.

I know what my first knives looked like and what most peoples early knives look like. I would not buy premium steel at first, but thats just me!

Have the blades hardened and tempered down to 60hrc and do a thicker convex grind and edge and they should be ok. The geometry of the blade itself and at the edge will change the toughness and the lower rockwell hardness will also help out too.
 
I appreciate the feedback. These aren't my first knives, I see that my wording may have suggested that. I should have said I'm trying to get started in knife making full time. I was in the blacksmithing club in college.

I have been out of school for about two years and have learned very fast that corporate careerism is not something I am capable of. So I have been saving and planning for about a year.

The reason I have been purchasing knives instead of saving for steel was that I was in an apartment with no way of building a shop environment. So instead I took the time to purchase a few select models with design characteristics I wanted to explore. It's one thing to read reviews and specs, but i figured having them physically in my hand to learn about their performance was a better use of my time.

I now have managed to find housing with a garage and so I am trying to get started quickly and efficiently.

Money is a concern for now because it has been an expensive month getting all of the equipment at once, but it's because I'm trying to minimize downtime on the weekends. The sooner I can get everything up and running the sooner I can see the viability of the transition.
 
Don't over analyze the impact toughness, you are making a knife out of 3/16 steel. Unless you are planning on stupid abuse your knife is going to be more burley than needed.

If you want a steel for glorified pry bar action I would look to 80CrV2 or a similar low alloy.
 
I'm somewhat of a new maker myself (amongst these guys I'll probably always say that) and therefore won't attempt to answer your questions but rather make a statement. I do not wish to discourage you at all, in fact quite the opposite. I read something here months back that stuck with me even though fulltime smith was never my intention. If you want to have a million dollars selling knives, start off with 2 million dollars.
 
Not a maker but a user / customer. Just to note that larger Cruwear blades do exist (bottom one below).

i-VWnzMTJ-X2.jpg


That being said, even though I’m a Cruwear fan, for a blade that size, I wouldn’t mind 3V, A8mod, A2, S7, etc., as long as there are a couple % chrome in it.
 
I'm sorry you took it that way .. it was not my intent. I was trying to be helpful. Knowing your location, I might have sent you a bar of 3-V or Cru-wear, or maybe some of both. I regularly help new smiths and new members that way.

As a moderator, your posting history is pretty much right there in front of me.
My comment on the recent knife purchase was to point out how much blade steel that would buy, not to chide you for buying it.
 
CPM Cruwear is plenty tough for your application. The impact toughness numbers do not always directly translate to reality and most steels are tough enough for normal applications. Steels like 1095 have been used and loved for years in large knives without issue. 1095 has a lower impact toughness (on paper) than freaking CPM 10V, yet its still well regarded as a "tough steel" among many knife enthusiasts.
 
Others have given you the best advice....you are probably overstating the value of the steel. The type of steel is much lower of importance with the quality of the knife.

I was the same way starting off. I still think about steel too much.

But your design will matter more.
Balance, handle design, sheathing, edge geometry, etc....

*you had some pretty great makers giving you good advice.

The gist of it is you just need to make Many more knives. So whatever it is to get you to make Many more knives will help you more. A lower cost steel will get more blanks to grind.

AEB-L is Way cheaper, and Way tougher than 3v, Magnacut, and Cruwear. It's great for kitchen knives, it's great for swords and large Beaters, it's great for edc.

Perfect your designs, perfect your build quality, build a fanbase.....
Then, worry about the "best" steels.


My opinion is the hardest thing about making a knife is..... "What's it going to be used for?". .(lots of questions need to be asked) once you Really know THAT, the rest just falls into place.


-Yes I have Cruwear blades over 5" in blade length.
 
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