Young Franken CPM 10V 68rc

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Many times before I've mentioned about edge steering - here is cpm m4 67rc edge damage from chopping dried cooked beef rib bone at 45 degrees angle and luckily I saw the evident:
sc8tP5M.jpg


Edge of a lower hardness (same steel volume) blade would rippled or rolled but the magnitude of damage probably be smaller than fractured (as shown above) from higher hardness blade.

Two ways (and combination thereof) to minimize/mitigate this problem: 1st - more steel volume. 2nd - less sharpness/keenness apex.
 
Luong,

I don't understand percussion point ... :o

About making it thicker or less sharp, you're saying making it blunter but still cut (Bluntcut) ? ;)
 
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https://en.wikipedia.org/wiki/Center_of_percussion
For the whole moving system (arm + knife), where all kinetic converted to impact with least torque/waste. For this chopper, COP is about 2" in front of handle when at impact the handle is below the edge (on the chopping block).

Wider apex to retards steering as long as entry psi is beyond material fracture/separation force. Imagine put sharp wings on an air plane (not even a super sonic) = wing chips :p

Latest CWF HT
10V: more/less same result as before
M4: Much better blade toughness. More room for improvement with some tuning
3V: Not grind & test yet but expect to attained near peak gain using this ht params

M4 - high sabre grind, edge geometry: 15dps and 0.03" thick 1/8" up from apex. I didn't thin it because that will mess up my pre-ht condition. This blade survived whatever chop & baton (pine,oak) I can mustered.
dUy2V75.jpg


Chris "Anagarika";16689804 said:
Luong,

I don't understand percussion point ... :o

About making it thicker or less sharp, you're saying making it blunter but still cut (Bluntcut) ? ;)
Click to expand...

Update: new cwf ht for 3V blade is spot on ~65+rc core. Blade is a lot tougher with extended elastic+plastic ranges.
 
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When you say center of percussion point I think that's the "sweet spot." Like the sweet spot of a baseball bat.

Anyway. I'd love to test some of what you're putting out. If I could take a 65 RC 3V chopper and hack up some ironwood and then turn around and bend that chopper over 45 degrees and it returns to true AND the edge is stable through both hard non-abrasive media and soft abrasive media, then I believe you'd have a real winner.

I'm excited for you and what you're doing, Luong.
 
COP != SP == zero rotation/pivot vs dampen vibration/shock-wave == impulse (fast stop) vs dynamic impact. So, if you bat (with SP) into a rigid object, you would feel a huge shock in hand/arm. OK, well at least this is how I think, heheh I could be way off.
 
Well, I plan to make new CPM M4 & 10V heavier choppers (new steels should arrive tomorrow). From projection, 10V probably won't get much improvement because it has way too much carbon - so C distribution gradient vector won't be meaningful unless a bar is 6+mm thick. I can get M4 to works for 3-5mm thick range. PD#1/cruwear/zwear/etc (~1.05%C) and lower carbon would work really well. HT tuning takes a few times to optimize.

'Gradient' & 'core' + M4 pic are hints of what I am doing for blade toughness - mostly a crude work around. I don't have equipment & gut to conduct a (maybe the) most crazy sophisticated ht step yet. Save that for mid 2017. For bigger knives/choppers, due to large size I skip 1 of 2 steps (involve equipment/instrument).

With well-tuned ht params - a 65rc 3V chopper should able to elastically bend more than 45 degrees. Edge should very stable but probably need 20dps bevel to chop into a block of ironwood/blackwood.

btw - metallurgy, sans voodoo/caca

bodog said:
When you say center of percussion point I think that's the "sweet spot." Like the sweet spot of a baseball bat.

Anyway. I'd love to test some of what you're putting out. If I could take a 65 RC 3V chopper and hack up some ironwood and then turn around and bend that chopper over 45 degrees and it returns to true AND the edge is stable through both hard non-abrasive media and soft abrasive media, then I believe you'd have a real winner.

I'm excited for you and what you're doing, Luong.
Click to expand...
 
bluntcut said:
btw - metallurgy, sans voodoo/caca
Click to expand...

Lol, if only some of these knife manufacturers could do what you and guys like dan keffeler, phil wilson, and nathan carothers are doing. Esee and buck aren't. If some of these guys tried your 1095 they wouldn't be saying esee (or whoever) has a world class heat treatment anymore. And if they knew enough about what big production companies are capable of they'd realize that there's no way they can do what guys like you can do. There's no way a company like buck can do multiple tempers with specialized brine quenching and tweaking the austenization temperatures a few degrees here and there and everything you guys do to really bring out the best in a steel. If someone thinks buck is bringing the best out of a steel like 420HC or esee is bringing the best out of a steel like 1095, they really need to check out what a real knifemaker and metallurgical student can bring to the table. What you're doing is exciting for our hobby.

The fact that you can make a relatively thin 10V chopper at 68 RC that can stand up to pretty much whatever is thrown at it is incredible. That flies in the face of what is conventionally known about knife steels. I just wish these guys would get a glimpse of what it takes to bring the best out of a steel and know that buck or esee or whoever is not and probably cannot do it.
 
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I agree* and thanks for your good words of support!

*
In economic perspective, probably 95th(reality maybe closer to 99th) percentile of edges in service out in the world, where apex is wider than 15um. Hence, users can't tell the edge retention difference between Great/awesome ht vs Average ht for blade with dull edge. For simplicity, says edge retention diff between G & A is linear from 1um wide apex is 100%, gradually drop toward zero when apex is 10+um. It would be foolish to pump investment into irrelevant ht improvement in current market, where you get higher return for adding ninja features.

If somehow a ht change the 95th percentile to 5um due to awesome stable working edge around this thickness. Aah, now competition forces companies/makers to match this new level of performance.

I've stated a few times about CWF HT - thinner apex is intrinsic of higher strength edge, when stability is given. Is this CWF HT close to 5um working apex? IDK & TBD. For my own R&D goals, I postulate that beyond cwf, there is/are not much room(low hanging fruits) to improve ht via thermomechanical transformation. In searching for ET, I need instrument (spaceship :D).

bodog said:
Lol, if only some of these knife manufacturers could do what you and guys like dan keffeler, phil wilson, and nathan carothers are doing. Esee and buck aren't. If some of these guys tried your 1095 they wouldn't be saying esee (or whoever) has a world class heat treatment anymore. And if they knew enough about what big production companies are capable of they'd realize that there's no way they can do what guys like you can do. There's no way a company like buck can do multiple tempers with specialized brine quenching and tweaking the austenization temperatures a few degrees here and there and everything you guys do to really bring out the best in a steel. If someone thinks buck is bringing the best out of a steel like 420HC or esee is bringing the best out of a steel like 1095, they really need to check out what a real knifemaker and metallurgical student can bring to the table. What you're doing is exciting for our hobby.

The fact that you can make a relatively thin 10V chopper at 68 RC that can stand up to pretty much whatever is thrown at it is incredible. That flies in the face of what is conventionally known about knife steels. I just wish these guys would get a glimpse of what it takes to bring the best out of a steel and know that buck or esee or whoever is not and probably cannot do it.
Click to expand...
 
Sharing Performance Ratio = community benefit/detrimental. Perhaps, my SPR could use some padding (by leveraging authority) ;)

[video=youtube;MIZrZ6YNGJg]http://www.youtube.com/watch?v=MIZrZ6YNGJg[/video]

If ^ that well worth, there are 11 more lectures from the same Prof.

To give your eyes a break from looking at small things - http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html
 
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