BCMW's ht chopping impact tests

[Camber]

THe adapted handle really does look secure, and for whatever reason it really goes well with the aesthetic of the blade.

And one day when you're taking orders, we'll have to talk about a JEST bolo. It looks great.

 

[BluntCut MetalWorks]

Thanks.

50 lbs of steels arrived today. The 5/16" bar is actually 0.370" thick - yep, almost 3/8" (0.375"). 1/4" bar measured 0.275" thick - normal. I will use the profile of 52100 jest bolo above for 0.370" thick W2. Hopefully, its final weight will be between 20-22 oz. Probably late next week before I start this W2 jest bolo + maybe 5/32" 52100 jest bolo at the same time.

Tomorrow, I will try to setup a station for low-hit-count chopping dried 2x4 douglas fir. For the current 52100(16.7 oz) jest bolo 10 hits would be great. Nifty aggressive goal for me, since for Nathan 3V light chopper (17oz), it tooks Dan Keffeler 8 hits to chopped through a 2x4 https://www.youtube.com/watch?v=TvUsh5FijcY

THe adapted handle really does look secure, and for whatever reason it really goes well with the aesthetic of the blade.

And one day when you're taking orders, we'll have to talk about a JEST bolo. It looks great.

 

[Camber]

WIth it being that thick, I bet you it will hold up at least a little better just because of that at the geometries you are going for.

 

[Spyder59]

Thanks.

50 lbs of steels arrived today. The 5/16" bar is actually 0.370" thick - yep, almost 3/8" (0.375"). 1/4" bar measured 0.275" thick - normal. I will use the profile of 52100 jest bolo above for 0.370" thick W2. Hopefully, its final weight will be between 20-22 oz. Probably late next week before I start this W2 jest bolo + maybe 5/32" 52100 jest bolo at the same time.

Tomorrow, I will try to setup a station for low-hit-count chopping dried 2x4 douglas fir. For the current 52100(16.7 oz) jest bolo 10 hits would be great. Nifty aggressive goal for me, since for Nathan 3V light chopper (17oz), it tooks Dan Keffeler 8 hits to chopped through a 2x4 https://www.youtube.com/watch?v=TvUsh5FijcY

Yeah baby!!

 

[BluntCut MetalWorks]

I cut a 0.156" thick 52100 jest bolo blank (cut from a 2" wide bar) weighted right around 20 oz. Probably it will sports a high sabre grind, maybe some tang skeletonize holes, iffy taper tang and use super light handle material. I think, completed weight around 13-14 oz would be fun to use. However...

dogrunner & others - what should be a good weight for this 0.156" thick chopper?

After cutting 2x 0.37" thick W2 jest bolo blanks (40 oz each), my bandsaw seems ungracefully aged :grumpy:

As for 2x4 low hit count chop test with 1/4" 52100 chopper. Made a couple setup with wood sawhorse with 2x4 and 2x6 backing - no go because the base gives too much. With left hand hold the 2x4 at an angle to a wood stump, chop with right arm, chop count (10, 8, 12, 10, 10, 9).

Just noted the specs on the 52100 you are planning. I like that steel and am looking forward to what spyderco does with it in the mili sprint. And I'm very interested in the performance you will get with your ht and that stock thickness. I like my choppers fast and light (relatively speaking). Heavy wears me out and my elbow tendinitis flares up. The .156 has my attention!

 

[BluntCut MetalWorks]

0.325" thick W2 jest bolo #1. Well, its near edge hardness is estimated about ~ 1point higher than my target rc. Yeah, on flat spot near spine, I targeted for 64rc. I light chopped some seasoned pine log, edge is fine. However, I need to harden a few small W2 test knives using same ht params as this W2 JB1. Rather zero-in hrc using small knives than break a large chopper.

Target completed weight ~24 oz (1.5 lbs)

W2 JB#2 has FFG. 52100 JB has high sabre grind. Both prepared but not harden yet.

 

[RX-79G]

Bluntcut,

I make knives, but not enough too speak from a deep well of experience. I do read about heat treating voraciously, so please forgive my skepticism:

52100 is a thoroughly hypereutectoid steel, so it forms a fair amount of carbides, which is good for strength, but not necessarily grain for toughness. 52100 also seems to have a reputation for being difficult to HT with retained austenite, due to all that extra carbon.
Given that this is a hard steel to heat treat, you are making a chopper, 52100 isn't thought of a "shock steel" like L6, doesn't get as fine a grain as something like 1084 or 80CR, why are you setting the hardness in the range of Japanese kitchen knives? Japanese cutlery isn't for butchering steer.


I'm asking to learn, not to criticize. You seem to be doing this with open eyes, but no one else appears to be making choppers of this kind high carbon, low alloy steel at the absolute peak hardness you can squeeze out of tempered steel in this class. Roselli manages to get up to 64 Rc with their 2% carbon blades, and Lauri gets their double quenched edges. But they only offer such blades in pretty short lengths. Is anyone else making chopping blade this hard?

 

[Camber]

Looking forward to the testing with the W2 when you get to it.

 

[dogrunner]

I cut a 0.156" thick 52100 jest bolo blank (cut from a 2" wide bar) weighted right around 20 oz. Probably it will sports a high sabre grind, maybe some tang skeletonize holes, iffy taper tang and use super light handle material. I think, completed weight around 13-14 oz would be fun to use. However...

dogrunner & others - what should be a good weight for this 0.156" thick chopper?

...).

You look like you are going to hit a good weight. I like about 16-17 oz for a light weight chopper and if you can make one in that range that is effective, I'd be pretty happy with it. Above that weight - up to 21 -22 oz, a well-balanced blade will still feel agile / controllable to me, but one that is a little heavier or balance is off will make my elbow sore pretty quickly. I am not a big strong guy though, so the big (or young and undamaged ) folks may laugh at my limits. But 16-17 oz is not too heavy to pack or use. Watching with interest!

 

[BluntCut MetalWorks]

After hardened (aim for 64-65rc) and cleaned up, it probably be 0.16" thick; 12.5oz. Completed weight could be 14-16oz depend on handle material used. Currently, without handle balance point is 3" forward from plunge line. I think a 15oz final weight would be a mighty powerful light chopper - ~chop 2x4 by 12 hits. ht warp could be a party-crasher...

You look like you are going to hit a good weight. I like about 16-17 oz for a light weight chopper and if you can make one in that range that is effective, I'd be pretty happy with it. Above that weight - up to 21 -22 oz, a well-balanced blade will still feel agile / controllable to me, but one that is a little heavier or balance is off will make my elbow sore pretty quickly. I am not a big strong guy though, so the big (or young and undamaged ) folks may laugh at my limits. But 16-17 oz is not too heavy to pack or use. Watching with interest!

 

[BluntCut MetalWorks]

I appreciate your open-minded question and remark, since open minded allows possibilities... At the same time we need at least 3 level of filters: Skeptical -> Critical -> Analytical.

* I ramble a little bit - dialogs for all readers *

Skeptical
A 65rc chopper? Hahaha, right Because there isn't a functioning 1km high sky-scrapper. So, either filter-out this or maybe these is a small chance of possibility?

Critical
Re-read post #17 above and http://www.bladeforums.com/forums/s...-Why-Use-Carbon-Steel?p=15797966#post15797966, are these scientifically sound or fantasy? Simple, just work through all parts and see which is/are false. Once, a part found as flawed, deductively other parts could also be flaw.

Analytical
Best to focus on the 2 big iffy/radical/suspected items: a1. SuperQuench high carbon steels; a2. 64+rc martensite hard-working matrix, than compare to common ht.

a1) SQ 52100/CruforgeV/etc - is this possible? Well, there are many of my posts about it and SQ knives in other people hands. Beside evidences from me, there aren't any 3rd metallurgical scrutinies to confirm or reject whether these knives are actually Super Quenched. I make SQ possible because aust solution is highly tailored/structured/prepared, so quench shock is not applicable nor liable for crack/ping hardened steel. Bottom line - use your critical filter.

a2) Strength of a chain = weakest link. Similarly to combinatorial Max Flow Min Cut. So if there are flaws in the matrix that initiate and then propagate failure. Impact is an impulse force, so strength and absorption load/capacity must be higher or diffusive to minimize damage. Friability of common carbides are much higher than matrix crystal and grain boundaries, except for odd shape(finger/fern) cementites - which are brittle. Plate martensite is weaker than lath martensite. Basically 2 long plates/twin lattices, where cementites easily precipitate. Plate interface is more easily sheer/crack and or directional force propagator (you want high directional changes/diffusion - i.e. can handle bigger load).

Industry invented/designed low carbon matrix steels. Done either with actual low mass % of Carbon or via affective cocktail of elements. If choosing between RA & plate martensite, RA is tougher - thus 3V/pd1/cruwear/etc.. Infi/S7/etc chose the lower C% route. Elements cocktail steers results toward certain desirable zone.

Using SEM/BSED/XrayDiff/etc... may bring to view that 64+rc matrix is strong & tough but too fuzzy to prove much.

Bottom line - actual products are shown here, however real/fake to be assess by 3rd parties.

Bluntcut,

I make knives, but not enough too speak from a deep well of experience. I do read about heat treating voraciously, so please forgive my skepticism:

52100 is a thoroughly hypereutectoid steel, so it forms a fair amount of carbides, which is good for strength, but not necessarily grain for toughness. 52100 also seems to have a reputation for being difficult to HT with retained austenite, due to all that extra carbon.
Given that this is a hard steel to heat treat, you are making a chopper, 52100 isn't thought of a "shock steel" like L6, doesn't get as fine a grain as something like 1084 or 80CR, why are you setting the hardness in the range of Japanese kitchen knives? Japanese cutlery isn't for butchering steer.


I'm asking to learn, not to criticize. You seem to be doing this with open eyes, but no one else appears to be making choppers of this kind high carbon, low alloy steel at the absolute peak hardness you can squeeze out of tempered steel in this class. Roselli manages to get up to 64 Rc with their 2% carbon blades, and Lauri gets their double quenched edges. But they only offer such blades in pretty short lengths. Is anyone else making chopping blade this hard?

 

[RX-79G]

I guess I don't see what being extremely well versed in the theory of steel microstructure has to do with executing a metallurgical feat that experimental bladesmiths with actual laboratories don't think they can accomplish.

It isn't that a 1km building can't be built. But it isn't going to be built by a construction company that has only built 10 story buildings up until now.

So you are either engaged in metallurgical discoveries well beyond virtually all your peers, or there is a conspiracy involving the true relationships between impact resistance, hardness, toughness and strength. If your claims are correct, I have to pick one of those two categories.

 

[BluntCut MetalWorks]

Looking back to my chopper making history (search my old posts about chopper) - my progress over 2+yrs is actually slow. Started out with a couple choppers around 54rc... gradually to 56, 58, 59. Then mid last year to arrived at 62rc. Now, I've made a choppers at 65rc - btw: medium swing W2 chopper chopped dried oak+knotty loquat branch + 2x4 - passed.

I am sharing what possible (plus a long lousy multi-years marketing hype). What I have done with ht is not a discovery, more like a bundle of well conceived ht steps all within normal metallurgical realm. Sorry, a giant leap forward in this field will have to wait

Obviously there isn't a conspiracy either. Are we happily calling a messy gumbo matrix bounded by metallurgical limits because mutual exclusiveness of these properties? Coherent understanding could lead to enhanced results.

I guess I don't see what being extremely well versed in the theory of steel microstructure has to do with executing a metallurgical feat that experimental bladesmiths with actual laboratories don't think they can accomplish.

It isn't that a 1km building can't be built. But it isn't going to be built by a construction company that has only built 10 story buildings up until now.

So you are either engaged in metallurgical discoveries well beyond virtually all your peers, or there is a conspiracy involving the true relationships between impact resistance, hardness, toughness and strength. If your claims are correct, I have to pick one of those two categories.

 

[RX-79G]

The "leap" is in the claim that a long blade HT'd to 65 Hrc is as sound or better than what 99% of the industry and bladesmiths would set somewhere closer to 55 Hrc. The science is the science, but if your blades actually work better (cut and don't break), you've basically proved a lot of other folks to be incompetent in their inability to apply that science the way you claim you can.

This isn't quite like some inventor that claims he made an engine that runs on water in his basement, but you are definitely making a very unconventional claim.

 

[BluntCut MetalWorks]

When my claims became facts, at that point - I've a recognized improved ht. My innovations are not and will never be justify/label others ht as incompetent or compromised. Steels & ht improvement are occurring over time - kudo to our learning ability and applied science!

For me, a 'Leap' = come up with material to build 2km high rise building or even better - a sky elevator

The "leap" is in the claim that a long blade HT'd to 65 Hrc is as sound or better than what 99% of the industry and bladesmiths would set somewhere closer to 55 Hrc. The science is the science, but if your blades actually work better (cut and don't break), you've basically proved a lot of other folks to be incompetent in their inability to apply that science the way you claim you can.

This isn't quite like some inventor that claims he made an engine that runs on water in his basement, but you are definitely making a very unconventional claim.

 

[BluntCut MetalWorks]

Hardened two 1/8" thick W2 3.5" blade, 0.013" behind edge thick, 12.5dps. Chopping & cross-grain batoning tests at 65.5rc hardness. No edge damage.

So, the edge of the W2 chopper above should be around 65.5rc. Since recent knives using same ht params end up with a tempered 65.5rc. I will slap a quick handle on the .325" thick W2 chopper and perform full tests. Initially edge geometry should be: 0.025" BET, 15dps (no micro bevel). If it passed all tests, I will test at 0.02" BET.

 

[Chris "Anagarika"]

Nice & Thin! :thumbup:

 

[shqxk]

Bluntcut,

I make knives, but not enough too speak from a deep well of experience. I do read about heat treating voraciously, so please forgive my skepticism:

52100 is a thoroughly hypereutectoid steel, so it forms a fair amount of carbides, which is good for strength, but not necessarily grain for toughness. 52100 also seems to have a reputation for being difficult to HT with retained austenite, due to all that extra carbon.
Given that this is a hard steel to heat treat, you are making a chopper, 52100 isn't thought of a "shock steel" like L6, doesn't get as fine a grain as something like 1084 or 80CR, why are you setting the hardness in the range of Japanese kitchen knives? Japanese cutlery isn't for butchering steer.


I'm asking to learn, not to criticize. You seem to be doing this with open eyes, but no one else appears to be making choppers of this kind high carbon, low alloy steel at the absolute peak hardness you can squeeze out of tempered steel in this class. Roselli manages to get up to 64 Rc with their 2% carbon blades, and Lauri gets their double quenched edges. But they only offer such blades in pretty short lengths. Is anyone else making chopping blade this hard?

I quite agreed with you beside the part "doesn't get as fine a grain as something like 1084 or 80CR"

52100 type of steel is known for being the finest grain steel you can have. Because it made with tighter tolerance composition than most other high carbon steel... most of them even being made with superior process for example Bohler's standard equivalence of AISI52100 which is R100 is made via vacuum melt and remelted process.

ฺBeside, the excessive carbide does not always mean to increase the grain size, its depend on type and how its being form.. In fact, the 1.5 chromium does have a big role for pinning grain boundary at austenitizing.

 

[RX-79G]

I quite agreed with you beside the part "doesn't get as fine a grain as something like 1084 or 80CR"

52100 type of steel is known for being the finest grain steel you can have. Because it made with tighter tolerance composition than most other high carbon steel... most of them even being made with superior process for example Bohler's standard equivalence of AISI52100 which is R100 is made via vacuum melt and remelted process.

ฺBeside, the excessive carbide does not always mean to increase the grain size, its depend on type and how its being form.. In fact, the 1.5 chromium does have a big role for pinning grain boundary at austenitizing.

My understanding is that 52100 forms some of the smallest carbides of the hypereutectoid steels, but steels that do not form carbides are actually tougher because they are more "homogeneous" in crystal structure. I shouldn't have said "grain size". 52100 will be more wear resistant than something like 1084 or L6, but not as tough at a given hardness.

What I'm gleaning from the OP is that he isn't making a tough blade (as would be typical for chopping) but one so strong that it simply won't fracture in use, since toughness drops as hardness rises. I just don't understand how that is going to happen.

 

[BluntCut MetalWorks]

Thanks. For kitchen uses (non-impact cuts), this blade supports 0.003"-0.005" BET and 7-10dps. I've tested a few of them.

Nice & Thin! :thumbup:

Interesting about Cr grain pinning - can't recall seeing that anywhere. If you don't mind, please explain and perhaps provide a link or 2.

Currently, I found my ht of W2 produced finest working grain size.

I quite agreed with you beside the part "doesn't get as fine a grain as something like 1084 or 80CR"

52100 type of steel is known for being the finest grain steel you can have. Because it made with tighter tolerance composition than most other high carbon steel... most of them even being made with superior process for example Bohler's standard equivalence of AISI52100 which is R100 is made via vacuum melt and remelted process.

ฺBeside, the excessive carbide does not always mean to increase the grain size, its depend on type and how its being form.. In fact, the 1.5 chromium does have a big role for pinning grain boundary at austenitizing.

There are many steels(e.g. white#1&2, blue#1&2, 1.2519, ..) beside 52100 can ht to produce carbides with dia smaller than 250nm.

My understanding is that 52100 forms some of the smallest carbides of the hypereutectoid steels, but steels that do not form carbides are actually tougher because they are more "homogeneous" in crystal structure. I shouldn't have said "grain size". 52100 will be more wear resistant than something like 1084 or L6, but not as tough at a given hardness.

I am in the process of hardening 2 additional W2 blades - targeted for 67rc & 68rc. Sure bugged me last night for not have done this sooner - doh! need to test boundaries/limits.

What I'm gleaning from the OP is that he isn't making a tough blade (as would be typical for chopping) but one so strong that it simply won't fracture in use, since toughness drops as hardness rises. I just don't understand how that is going to happen.