Backyard tinker with CPM 3V 65mm fixed/paring blade

[BluntCut MetalWorks]

Lately I've tinkered around with steels in my backyard.

I want to find out more about CPM 3V knives without paying premium prices. Bought some 3v from Alpha Knife Supply. Divided a 8.8x1x0.46 into 4 equal pieces to make small paring knives. Repeat Austenited & quenched using a propane torch blew on a pile of charcoal until the hardness similar to my 52100 60rc blade. Didn't temper at all since I don't have a HT oven (need 1K+ F for tempering). (alright, go ahead to call this a hack/screwup/whatever ht).

Thanks for watching & comments...

[video=youtube_share;LRGztudIUyQ]http://youtu.be/LRGztudIUyQ [/video]

Stabbed & cut a can & tip dug into a piece of dry oak would seriously damage most knives. This little knife did quite well. Last time, I cut a can with my Spyderco CF Stretch in zdp-189, the blade lost almost 2mm (look like a saw) height. While a BM pardue fixed blade in D2 (at least 3mm thick) lost 1.2 mm height + lost 1mm tip when stabbed & pried.

More 3V steel bars are in the mail - perhaps, I will send out to HT new knives so I have a better comparison between back yard vs commercial/professional.

So far for backyard steels tinkering - cpm 3V is most impressive compared to s90v, elmax, 52100, 1095, 1080.

 

[BluntCut MetalWorks]

I straighten the bented blade & sharpened it. Lost about 0.5mm of blade height due to damages from can cutting tests. It's ready for more actions...

Today I finished a 115mm (~4.5") 1mm thick fixed blade. Olive wood handle (yep, a small curve branch I trimmed 18mos ago) with 2 coats of tung oil. Sharpened around 30* inclusive angle. It served kitchen choppery duty this evening. Hacked vegies and 2 game hens into 0.5" pieces through bones for a salty ginger dish. It stays sharp & no dings from bones. Took these pictures after dinner.



edit: my youtube reply on hardness testing
For RC guessing - 60 or so - I used three 52100 plates harden ~58, 60 and 62 as reference for scrapping & denting. I use a punch strike with a mallet at certain height, giving me good rc guess-timate.

 

[BluntCut MetalWorks]

My back yard $20 high temperature 2200+F / 1200+C forge/oven. Here is my new video to show a successful quench for simple to super steels.

Thanks for watching & comments.

[video=youtube_share;bpbgXAYqcwk]http://youtu.be/bpbgXAYqcwk[/video]

RichardJ - Thanks for advices/guidances emails!

These posts sort of in the gray area between this tinkering sub & shop-talk. Well, I am not a knife-maker so it's more comfy to be here (aaaah ignorance is bliss)

 

[sloth357]

1mm thick! lol that is awesome.. so it sounds like you are impressed with its performance?

I was hoping you'd put that mora through the same tests.. that would show more IMO, thanks though for the time and effort doing all this

 

[BluntCut MetalWorks]

1mm thick! lol that is awesome.. so it sounds like you are impressed with its performance?

I was hoping you'd put that mora through the same tests.. that would show more IMO, thanks though for the time and effort doing all this

Mora convex edge is quite thick-behind-the-edge, so damages was minimal as expected.


note: this 'can' is slightly thicker than the one tested with 3v knife. after re-watched the video, look like the Mora tip got blunted from hitting the vise.
[video=youtube_share;-VMsIlYkfMI]http://youtu.be/-VMsIlYkfMI[/video]

 

[ryxlyx]

Good stuff. Got a BR Liten Bror in 3V that's collecting dust, I'm gonna carry that tomorrow....

 

[BluntCut MetalWorks]

For hardness/RC-guessing: I was using a dental punch to indent the blade with a mallet and compare to punch marks on production knives with known hardness. Why not improve it. So, I made a couple carbide tip indenters, which can operate via press down or drop-down strike. Both Wc tip easily indented (zdp-189 at 66rc, a file, ..)

 

[BluntCut MetalWorks]

Instead of create another grey-topic/sub thread, I tinker-added this cpm-m4 blade.

My goal was to create a m4 blade with maximum hardness but avoid warpage, haha it's cracked. I didn't really see the crack after I tempered it on the cooking propane burner sandwiched between 2 thick 1080 bars. It's ridiculously hard, tungsten carbide tip barely some sort of scratches, all are very shallow. Something is goofy because the W tip has easier time scratch a Stretch CF zdp189 blade.

I heard the 'snap'/crack during quenching but I thought was hmm what was that . I decided to test this cracked blade anyway, hence to guide my subsequent blades.

Performance per bevel angle (inclusive).
14 - whittle -> edge rolled
21 - whittle -> stable. excessed 30lbs pressure whittle -> tiny edge rolled
40 - whittle -> rock solid. chop -> minor rolled

Sharpness: tree top (dmt ee + stropped on white compound leather).
Retention: didn't test.
Tip dig: passed.
Stab & cut can: will test with a non-cracked blade later (hopefull 'when' not 'if').



btw - scratches on the tang made from tungsten tip (indenter from previous post).

 

[Chris "Anagarika"]

It seems you're having good times there.

Time to become a knife maker (no more bliss )

 

[BluntCut MetalWorks]

It seems you're having good times there.

Time to become a knife maker (no more bliss )

That's right, gotta keep the 'good times', whose want work&worry of a knife maker anway

I baton the cracked m4 until it broke. Here is the 15x pic of the broken surface. Nice small uniform grain. Heheh see that surface layer of decarburization from excess hi-temp.


I re-quench the broken blade at a slower cooling rate, worked well. Of course - I made another blade, it's being temper right now. I didn't grind at all before ht, plus slow down the cooling rate, so it's straight & no crack.

 

[JayGoliath]

Your test results is convincing. I appreciate all the work and effort.
Thank you very much.

Are you going to try the rust resistance of 3V soon?

 

[BluntCut MetalWorks]

Your test results is convincing. I appreciate all the work and effort.
Thank you very much.

Are you going to try the rust resistance of 3V soon?

I wasn't going to test rust resistant. Please suggest some simple tests, if not complicated, I would gladly do it.

So far four 3v knives with regular usage, bevels are not as bright but no patina. Didn't rust from oily-sweat nor from sheathed a wet blade. My 2 friends use my gifted 3v knive almost daily at the beach (pinic benches, no salt water), a little dulled that's all. Comparatively my cpm-m4 blades are usually gradually darken as weeks go by. Carbon knives either get patina or rust quick.

I just put some pineapple juice on a 3v blade and sheathed it. I'll post the result tomorrow.

 

[BluntCut MetalWorks]

3V knife with pineapple juice on blade for 12hrs - no rust.
Another 3V knife with vinegar on blade for 12hrs - no rust nor patina.

3V has 7.5% of Chromium and remain as Cr (instead of CrC) after ht, so rust resistant should be good.

 

[sharpandsafe]

Hey Bluntcut,

3V has a reputation for pitting. Can you use your microscope to check for micro-pitting at the edge on the knives you used for the rust test? This is the only thing that is making me hesitate in buying a knife in 3V. So far, your tests have gotten me pretty excited about this steel!

EDIT:

You may also want to test a saltwater solution for rusting. Ocean salinity is about 3.5% by weight, or 35 grams of salt per liter.

 

[BluntCut MetalWorks]

Hey Bluntcut,

3V has a reputation for pitting. Can you use your microscope to check for micro-pitting at the edge on the knives you used for the rust test? This is the only thing that is making me hesitate in buying a knife in 3V. So far, your tests have gotten me pretty excited about this steel!

EDIT:

You may also want to test a saltwater solution for rusting. Ocean salinity is about 3.5% by weight, or 35 grams of salt per liter.

Salt water will rust any carbon based steels, Cr slows the rust rate down. Well, here is result for 3v in maximum salted water for 90 minutes

I didn't see any rust, patina, pits using 22x loupe.