BCMW's ht chopping impact tests

[chiral.grolim]

It didn't.


Just something to look at.

What an awesome photo :thumbup::thumbup::thumbup:


I watched every video, am subscribed to the channel. The videos were quite long, showing the hardness tested to confirm actual hardness prior to impact-testing. The stone image presents some of the aftermath of how the blade was used in the video, and all that happened was dulling of the edge. The blade did NOT shatter. Only problem experienced was torquing the skinny tang, THAT snapped - good evidence for tempering the tang

It is often asserted that as hardness goes up, toughness goes down. While this is true in specific context it is not necessarily the case when comparing non-like materials. A blade HT'd one way can behave VERY differently from a blade HT'd another way, even one of the same steel, because the two are structurally distinct as a result of the HT process.

Luong is moving toward a steel that is closer and closer to the edge-stability of sintered hard-metals like W-Co (ceramic) while retaining the toughness of much softer steel.
This is not unlike Jerry Busse's efforts to develop INFI steel and also SR101 (52100mod) - it's not just the steel but also the HT process they use to try to generate a blade that can be 60+ Rc and yet sustain only minimal damage in high-energy impact scenarios using normal (thin) knife cutting-geometries (e.g. 20-dps, 0.020").
Nathan the Machinist is doing this same thing with CPM-3V - tweaking the HT process to squeeze more hardness AND more toughness into the matrix.

Luong is "jumping the shark" - squeezing the MAXIMUM hardness into the blade and looking for that same level of toughness. To do this, it behooves him to test with the actual maximum hardness, i.e. no temper, as a CONTROL.

Again, AWESOME pic

 

[BluntCut MetalWorks]

Thanks:thumbup: - Chris, bodog & Chiral!

Chiral - the 67.25rc blade tang didn't shattered because it was torched (by a mini torch, while the blade in water) beyond spring-tempered. Video ended when the wood handle cracks in 3 sides.

After 2 additional round of testings - the handle was too broken(after fixes with CA & expoxy) to continue. So I dug/split the handle to examine what inside look like...

 

[BluntCut MetalWorks]

52100 0.175" thick jest bolo: aimed for 65rc, would like 66rc, got 65.75rc

Multiple-chops 2x4 in less than 10 (mostly around 8) hits. Very deep penetration into seasoned oak. Small olive branch seems to explode on impact (several times) - Twice, I thought the edge was a goner. A best one among JB bunch - thinness reigns!

 

[BluntCut MetalWorks]

OK now, it's too thin...

when too soft = rippled & rolled
when too brittle = cascade failure or a very large chip

No roll nor chip, just rippled.

 

[Chris "Anagarika"]

Luong,

I have had Henckel cleaver rippled when chopping coconut. I don't think sharpen to more obtuse apex will help, because the ripple in my case went up higher than the sharpebed edge bevel, which made me think it seems the structural strength is not enough. I can't think of how to fix the Henckel though, except not to use it that hard.

Now such jobs has bee relegated to BCMW 52100 SU :thumbup:

In your 52100 JB, perhaps you'll make a thicker one?

 

[HeavyHanded]

I would have been absolutely amazed had it continued to have zero damage at those dimensions - still impressive that it didn't fail more dramatically or chip out. You certainly are perfecting the pattern in the meantime.

 

[BluntCut MetalWorks]

Thanks, Chris!

I still remember how fun it was chopping fresh fallen pine tree a near lake in the NW. Glad you didn't throw away the SU (slicer utility) 52100 I made in early stage of my ht journey.

Luong,

I have had Henckel cleaver rippled when chopping coconut. I don't think sharpen to more obtuse apex will help, because the ripple in my case went up higher than the sharpebed edge bevel, which made me think it seems the structural strength is not enough. I can't think of how to fix the Henckel though, except not to use it that hard.

Now such jobs has bee relegated to BCMW 52100 SU :thumbup:

In your 52100 JB, perhaps you'll make a thicker one?

I view - edges (variable thin cross section) are the extreme tests for crystal lattices.

I would have been absolutely amazed had it continued to have zero damage at those dimensions - still impressive that it didn't fail more dramatically or chip out. You certainly are perfecting the pattern in the meantime.

In the process of hardening the 2nd 0.325" thick JB. 66-66.5rc is the target working/in-use hardness. Will full zero grind this chopper, then reprofile to ~0.01" BET, 12/15dps (12 bevel, 15dps micro w/ face length ~0.002").

Why BET(behind edge thickness) is so thin in light of my rippled edge above? After some analysis & thoughts (didn't test yet, just brain) - micro steering lead to macro deformation. So 15dps or 20dps (if need be) could stop an initiation of micro steering. I think, 2" FFG with edge geometry 0.01" BET at 65+rc has enough backing to support hard wood chopping activities. Just don't hack rocks.

edit: tested against knotty 2x4 and oak: 0.175" thick 52100, 0.01" BET, 12dps/15dps-micro. Passed.

 

[bodog]

"tested against knotty 2x4 and oak: 0.175" thick 52100, 0.01" BET, 12dps/15dps-micro. Passed."

I don't see many other makers testing to the same extremety.

 

[BluntCut MetalWorks]

Limits / Destruction chopping tests.

0.175" thick 65.75rc 52100 JB, 12dps/15dps-micro, 0.042" thick at 0.25" up from apex.

Against knotty 2x4 & oak: 0.008" BET. Passed.

Against knotty 2x4 & oak: 0.007" BET. Passed.

Against African Blackwood: 0.007" BET. Major chips, then quickly destructed. v-notched/chips toughness is below my expectation. From breakage surface, I have a pretty good idea what is/are not optimal.

Time to work on the newly hardened 0.325" thick W2 jb. Heading toward destruction, I guess.

 

[BluntCut MetalWorks]

0.325" thick W2 JB, 66rc, FFG (decided not zero full grind)
0.02" BET, 15dps (no micro)

Chop tests:

2x4 - passed.
oak - passed.
olive - passed.
African Blackwood - passed (20 chops) with a small chip.
Sand stone - passed (1 chop split).
Granite rock - 1 chip (2 chops); pic below

Next - thin BET to 0.01" and sort of repeat tests above.

 

[Chris "Anagarika"]

The progress is exciting!

 

[BluntCut MetalWorks]

Thanks, Chris!

I shouldn't folded/skipped a tiny process with that 52100 JB - *hopefully, won't forget or too over confidence *

The progress is exciting!

 

[BluntCut MetalWorks]

Strength is the key for cutting; chopping; bulletic impact; etc interactions. Toughness is really just about minimizing - distance & volume - the damage/loss when the exerting force exceed TS (and or UTS). Fabric structure is ideal, unfortunately steel matrix default formation is in a lattice form, unless your ht can knits

 

[Chris "Anagarika"]

.... default formation is in a lattice form, unless your ht can knits

The skipped/folded process knitting loose?

 

[HeavyHanded]

0.325" thick W2 JB, 66rc, FFG (decided not zero full grind)
0.02" BET, 15dps (no micro)

Chop tests:

2x4 - passed.
oak - passed.
olive - passed.
African Blackwood - passed (20 chops) with a small chip.
Sand stone - passed (1 chop split).
Granite rock - 1 chip (2 chops); pic below

Next - thin BET to 0.01" and sort of repeat tests above.

This also has not been tempered?!

I look forward to knitted lattice.

 

[BluntCut MetalWorks]

ND. The tang and a small section on spine are torched. Drill bit has a fine grain lattice.

Thoughts on proof/verification
x rockwell hardness - no need
x nanographs - nah
x charpy xyz - nah
x ...

Perhaps, existence is a simple and scientific proof? A hard working chopper blade: 0.01" BET, less than 0.05" thick at 0.25" from-cutting-edge, 15dps edge bevel. Acceptance comfort/assuring: Hand-on witnesses sort/could of provide that.

Your thoughts?

This also has not been tempered?!

I look forward to knitted lattice.

 

[BluntCut MetalWorks]

BluntCut MetalWorks 20160307
W2 chopper
sub 0.01" edge thick; 15 dps sharpening bevel

Make a few chops to a 2x4 and seasoned red-oak.

Thanks for watching 5 minutes video and comment.
https://youtu.be/HcJVWaCoQuA

 

[HeavyHanded]

ND. The tang and a small section on spine are torched. Drill bit has a fine grain lattice.

Thoughts on proof/verification
x rockwell hardness - no need
x nanographs - nah
x charpy xyz - nah
x ...

Perhaps, existence is a simple and scientific proof? A hard working chopper blade: 0.01" BET, less than 0.05" thick at 0.25" from-cutting-edge, 15dps edge bevel. Acceptance comfort/assuring: Hand-on witnesses sort/could of provide that.

Your thoughts?

Good is as good does. Most (including me) do not really care about the numbers anyway as long as it works - hands on is all that matters. That said, I am very surprised by the results you are getting on this battery of tests.

Aside from impact have you considered doing any lateral load testing. Maybe edge down on red oak and scrape like a steering wheel? While being a somewhat mild test compared to some, is murder on many a good blade in my experience once the edge has been thinned out.

 

[Chris "Anagarika"]

I agree with Martin. At this development stage, you don't have to proof to anyone buy yourself.
All the sharing & nice photos are welcome though, I do enjoy it

Perhaps later when BCMW launches, you might want to make some kind of 'Proof!' Videos for the prospective buyers. Not to that CS level but at least the concept/thinking that set BCMW apart.
:thumbup:

 

[BluntCut MetalWorks]

Martin, thanks the advice. Scraping to oak and much harder wood like olive don't do much to this edge. Micro-chip occurred when scraping African Blackwood, Katalox, Lignum Vitea Argentine - however the edge continue to works well because of sharp 90* (micro-chipped) scraping edge. A ductile edge rolled would forms a smooth radius, become like scraping with a small rod, edge is dead.

Good is as good does. Most (including me) do not really care about the numbers anyway as long as it works - hands on is all that matters. That said, I am very surprised by the results you are getting on this battery of tests.

Aside from impact have you considered doing any lateral load testing. Maybe edge down on red oak and scrape like a steering wheel? While being a somewhat mild test compared to some, is murder on many a good blade in my experience once the edge has been thinned out.

You are right and at the same time - external extra eyes & brains could spot a few things I might be blind/unbeknown/etc.

By skipped over a tiny process in my hardening - W2 68, 67.25, 66 2nd JB and 65.75rc 52100 JB - I've learned, a tiny off here ain't tiny when arriving/missing Mars!

2nd W2 JB - ht landed on Mars but in wrong hemisphere .

I agree with Martin. At this development stage, you don't have to proof to anyone buy yourself.
All the sharing & nice photos are welcome though, I do enjoy it

Perhaps later when BCMW launches, you might want to make some kind of 'Proof!' Videos for the prospective buyers. Not to that CS level but at least the concept/thinking that set BCMW apart.
:thumbup:

1st 52100 JB; small W2 67.5rc; 1st 0.325" W2 JB will be harshly tested next. Once done with these 3, I plan to conduct another round of testing with 1 or 2 thin jb and smaller blades in W2/52100/CruforgeV/O1. Mondo JBs are too exhausting & expensive to tinker with.