Destroyer in CPM-M4 hard use test

Derek Bergstrom

Derek Bergstrom

Joined
Mar 5, 2014
Messages
140
Hey all, i have my prototype here i did some abusive work with today and thought it share.
Steel is CPM-M4
Blade length is 7 inches, 5/16ths thick 2 inches wide full flat grind and bead blasted
here i can shave some leather into very thin pieces.
Here is an overhead picture of the knife
I did some deconstructing today and used all of my strength to pry nailed boards apart with my knife
i chopped through 3 2x4s before my friend saws alled his way through 2

I used a 3lb mallet to split a brick in half with two knives, one cheaper stainless one that yes it may be a lot thinner but i just wanted some kind of comparrison
here is my edge after the brick
closeup of the stainless knife after the brick

I know that axes are for chopping and prybars are for prying and razor blades can cut leather into small pieces but i was intrigued and wanted to do some testing of my knifes performance and i think it held up well. I am a new knifemaker and have some cosmetic blemishes im working on, but for a start of a career i am doing my best and thought id share.
 
Cypress, this man just demonstrated that the quote in your sig can be applied to CPM-M4 steel, too. :D

If it can handle splitting bricks that well, I think you have designed a blade that would give a Busse a run for it's money.
 
Im not asking quite as much for mine as well, but they have a long lasting rep and im the little guy so im not prancing around saying im the best like they do, at a gun show or in person ive heard from collectors they basically say to your face if you dont own one of your knives, youre not *blank* but that could have just been a misinterpritation of the individual so dont quote me on that one, im just saying "here is my knife i hope it serves you well, and for all of those companies who say they make the best knife and use mid grade stainless, well, youre guilty of not doing your best of protecting them in an emergency. and yes i plan to duracoat them in the future. thank you guys for your kind words, this lifts the heart and helps a young smith keep at the grinder
 



so after the brick i used it to clear some brush it did a lot of one hit wacks. also the board its sticking out of is anchored in the cement and i wedged the knife in and my friend who weighs 230 lbs can stand on it without blade failure



FOUR!

here is a steel wasp killer can i stabbed repeadedly and then batoned in half
 
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Grease said:
Cypress, this man just demonstrated that the quote in your sig can be applied to CPM-M4 steel, too. :D

If it can handle splitting bricks that well, I think you have designed a blade that would give a Busse a run for it's money.
Click to expand...

With a knife that has that edge and blade geometry it's not really all that difficult... ;)

There are a number of stainless steels that can repeat that no problem given the same specs, M4 isn't exactly the toughest steel around. That's not even getting into steels like S7 and 3V that aren't stainless.

Although the knife does seem to be pretty nice and designed towards more extreme type of use.
 
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Derek Bergstrom said:
Hey all, i have my prototype here i did some abusive work with today and thought it share.
Steel is CPM-M4
Blade length is 7 inches, 5/16ths thick 2 inches wide full flat grind and bead blasted

I used a 3lb mallet to split a brick in half with two knives, one cheaper stainless one that yes it may be a lot thinner but i just wanted some kind of comparrison
here is my edge after the brick
closeup of the stainless knife after the brick

I know that axes are for chopping and prybars are for prying and razor blades can cut leather into small pieces but i was intrigued and wanted to do some testing of my knifes performance and i think it held up well. I am a new knifemaker and have some cosmetic blemishes im working on, but for a start of a career i am doing my best and thought id share.
Click to expand...

That stainless knife is a lot thinner and either hollow or Sabre ground, what your knife is twice as thick behind the edge and has almost twice the spine thickness, what knife it was doesn't even matter.. Don't know what knife it was and don't care....

Just thought I would mention it.... I would recommend if you are going to do a comparison at least use a knife that has close to the same specs.... Just a thought....

That knife does look like a tank. :)
 
Ankerson said:
That stainless knife is a lot thinner and either hollow or Sabre ground, what your knife is twice as thick behind the edge and has almost twice the spine thickness, what knife it was doesn't even matter.. Don't know what knife it was and don't care....

Just thought I would mention it.... I would recommend if you are going to do a comparison at least use a knife that has close to the same specs.... Just a thought....

That knife does look like a tank. :)
Click to expand...
Hi there Jim, ive always enjoyed your videos and reviews and understand the practicality of your response but here is where i stand at the moment.

i did say "yes this knife is much thinner but i just wanted a comparrison".
i never said anywhere this is the best knife ever made ever everyone else is junk. every knife has a purpose and a value.
if you would like to supply me with a knife of similar specs ill go ahead and do it at your request. ive done this with two other 5/16ths thick knives that failed miserably but they are some of my favorites that got me hooked on the thickness and id rather not put down other companies.
im please with M4s edge holding, edge stabilty, and overall toughness.
if you want a knife that will just and only do well at beaing beaten in a vice in the tang with a hammer then sure theres better steels for that. if you want something more abrasion resistant im sure tungsten carbide will hold longer.
i personally think this is a good outdoor use knife, and im not going to say anything negative about any other company or product because as everything in the knife world is a compromise, your preferances could very well be met better by something else but this is perfect for me. as ive originally wanted this knife to be a chopper ill probably thin the edge down quite a bit as ive discovered how stable M4 is.
as for the thickness? i like it and thats why i did it and i and every one else is allowed to have an opinion and a preferance. i dont know how tough M4 is since ive never taken it to a breaking point. But i was hoping to contribute to the knife world a little bit here and dont know of anyone who has hard use tested M4 in a knife form and i did it with something i made and hope to gain some appreciation. im very pleased with its performance.
If there is another steel that can do this good, well cool, good to know if someone needs it in an emergency i dont have the only thing that could have saved their live
 
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Ankerson said:
With a knife that has that edge and blade geometry it's not really all that difficult... ;)

There are a number of stainless steels that can repeat that no problem given the same specs, M4 isn't exactly the toughest steel around. That's not even getting into steels like S7 and 3V that aren't stainless.

Although the knife does seem to be pretty nice and designed towards more extreme type of use.
Click to expand...

I wanted a knife that will hold an edge. i called Gayle bradley and we talked for a while so i went M4. My friend bought me a contego and in 3 months my ocd has not made me sharpen it yet after cutting boxes every day, digging up plants out of dirt, and cutting sheet metal, just stropping it every time i use it has left it with a shaves kinda ok edge which is plenty useful for boxes and such and thats why i like it. im doing more edc friendly sized knives with much thinner edges in the near future.
The complex alloy intrigues me. tough yet very hard, yet easy to sharpen. for me, it is the perfect edged tool material. i cant think of anything that M4 wouldnt be good at... hammer, pry bar, ax, chisel, wear plate, razor blade, knife ect. I may be a little behind in knife testing like you do, i dont own M390 yet or cru wear or elmax or infi, someday, but i had to put my hobby aside for my family and now im focusing on making knives and i think M4 is a good place to start for a premium material. 1095 works, i have nothing against it. so does 440C. This is just my thing.
 
It looks like you gave it a very nice edge :thumbup:

Out of curiosity, why 5/16" thick with only a 7" blade? It could have a lot more chopping power with more length and still be able to pry laterally with such thickness... How much does it weigh?
Why so thick and CPM-M4? Is it inspired by a Bladesports competition knife? Why the enormous ricasso?

Thank you for this contribution to the forums, please keep it up :thumbup:
 
Derek Bergstrom said:
Hi there Jim, ive always enjoyed your videos and reviews and understand the practicality of your response but here is where i stand at the moment.

i did say "yes this knife is much thinner but i just wanted a comparrison".
i never said anywhere this is the best knife ever made ever everyone else is junk. every knife has a purpose and a value.
if you would like to supply me with a knife of similar specs ill go ahead and do it at your request. ive done this with two other 5/16ths thick knives that failed miserably but they are some of my favorites that got me hooked on the thickness and id rather not put down other companies.
im please with M4s edge holding, edge stabilty, and overall toughness.
if you want a knife that will just and only do well at beaing beaten in a vice in the tang with a hammer then sure theres better steels for that. if you want something more abrasion resistant im sure tungsten carbide will hold longer.
i personally think this is a good outdoor use knife, and im not going to say anything negative about any other company or product because as everything in the knife world is a compromise, your preferances could very well be met better by something else but this is perfect for me. as ive originally wanted this knife to be a chopper ill probably thin the edge down quite a bit as ive discovered how stable M4 is.
as for the thickness? i like it and thats why i did it and i and every one else is allowed to have an opinion and a preferance. i dont know how tough M4 is since ive never taken it to a breaking point. But i was hoping to contribute to the knife world a little bit here and dont know of anyone who has hard use tested M4 in a knife form and i did it with something i made and hope to gain some appreciation. im very pleased with its performance.
If there is another steel that can do this good, well cool, good to know if someone needs it in an emergency i dont have the only thing that could have saved their live
Click to expand...

I don't own any big heavy beaters anymore, sold them all off in the past 2 years. ;)

Other than the HI stuff I have, but that will be going up also....

The only reason I commented was the difference between the two knives, rather large difference....

I think you will contribute just fine to the knife world, just keep doing what you are doing and testing different geometries and steels with different HT and tempering protocols. :)
 
Derek Bergstrom said:
I wanted a knife that will hold an edge. i called Gayle bradley and we talked for a while so i went M4. My friend bought me a contego and in 3 months my ocd has not made me sharpen it yet after cutting boxes every day, digging up plants out of dirt, and cutting sheet metal, just stropping it every time i use it has left it with a shaves kinda ok edge which is plenty useful for boxes and such and thats why i like it. im doing more edc friendly sized knives with much thinner edges in the near future.
The complex alloy intrigues me. tough yet very hard, yet easy to sharpen. for me, it is the perfect edged tool material. i cant think of anything that M4 wouldnt be good at... hammer, pry bar, ax, chisel, wear plate, razor blade, knife ect. I may be a little behind in knife testing like you do, i dont own M390 yet or cru wear or elmax or infi, someday, but i had to put my hobby aside for my family and now im focusing on making knives and i think M4 is a good place to start for a premium material. 1095 works, i have nothing against it. so does 440C. This is just my thing.
Click to expand...

M4 isn't a bad place to start.

I guess over time it will broaden with testing and requests so who knows what the future may bring.
 
Ankerson said:
I don't own any big heavy beaters anymore, sold them all off in the past 2 years. ;)

Other than the HI stuff I have, but that will be going up also....

The only reason I commented was the difference between the two knives, rather large difference....

I think you will contribute just fine to the knife world, just keep doing what you are doing and testing different geometries and steels with different HT and tempering protocols. :)
Click to expand...
No dont sell the kukris :( !

Jim, tested it against a 440 imitation trailmaster style knife. here is the edge after a penny, my knife is on the left


the 440 knife seemed to roll rather than chip, which would of course imply a softer steel, and realistically for a big knife is tougher and perhaps better suited. mine is at 62, perhaps 60 would be better for the big knife.



lastly i hammered the spine of my knife and forced the edges to do some unfriendly cuddling. yeah 62 is seeming to be a bit hard and it chipped a little at a time, but a wack edge to edge, my knife was undamaged compared to the stainless one. the stainless knife is 1/4 thick. in the picture the shiny one behind the beat up ugly thing is the stainless one
 
Derek Bergstrom said:
No dont sell the kukris :( !

Jim, tested it against a 440 imitation trailmaster style knife. here is the edge after a penny, my knife is on the left


the 440 knife seemed to roll rather than chip, which would of course imply a softer steel, and realistically for a big knife is tougher and perhaps better suited. mine is at 62, perhaps 60 would be better for the big knife.



lastly i hammered the spine of my knife and forced the edges to do some unfriendly cuddling. yeah 62 is seeming to be a bit hard and it chipped a little at a time, but a wack edge to edge, my knife was undamaged compared to the stainless one. the stainless knife is 1/4 thick. in the picture the shiny one behind the beat up ugly thing is the stainless one
Click to expand...


Yeah I think 60 might be the ticket unless you want to do thinner knives and need more edge retention then you could bump it up into the 63-64 range, hunters etc.
 
Ankerson said:
Yeah I think 60 might be the ticket unless you want to do thinner knives and need more edge retention then you could bump it up into the 63-64 range, hunters etc.
Click to expand...

thats the general consensus. random trivia, out of hardening M4 is at 66 found that interesting.
So for my smaller edc blades harder than 62 may be good then? i have chip o phobia but M4 is so stable for just whittling and edc stuff i suppose realistically it would be fine. the GB is at 64 i believe and my friends has done great, after having 3 large steaks cut on ceramic plates it was a little dull at the tip but not really damaged or anything
 
Derek Bergstrom said:
thats the general consensus. random trivia, out of hardening M4 is at 66 found that interesting.
So for my smaller edc blades harder than 62 may be good then? i have chip o phobia but M4 is so stable for just whittling and edc stuff i suppose realistically it would be fine. the GB is at 64 i believe and my friends has done great, after having 3 large steaks cut on ceramic plates it was a little dull at the tip but not really damaged or anything
Click to expand...

Yeah you could do some nice thin Skinners at 64 - 66 as long as the people know that's what they are for.

I would think 62 - 63 would be fine for an edc blade. :)
 
trey999 said:
Great knife, Derek. And it's awesome that you show your tests on the internet.
Click to expand...

Thanks for the compliment, i hope to have 3 more for sale at the end of the month as well as a few other knives with variations i hope people like. its hard to put myself out there but i hope the risk pays off :)
 
Brumby53 said:
Thanks - you sure gave it a workout! Interesting discussion
Click to expand...

originally i just wanted a knife that could chop well and hold an edge for a long time so this one i think i may thin down a lot for better bite into the wood. ill carry it and use it and post more stories over time
 
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