S90V Chopper

[BluntCut MetalWorks]

I'm planning to make a s90v chopper with specs: 2"W x 0.180" Thick, 16.5" OAL, 64rc, 20dps, 0.025-0.030" BTE

Obviously chopper doesn't need much wear resistance, where impact & shock resistance are crucial. Nevertheless, it would be fun/educational to see proof of concept/ht in action/video.

Test via my max chop speed at tasks: 2x4, hardwoods and very high janka woods, dried pork rib bone, [ your susggestions ? ]. Performance = 'A' no visible damage, 'B' no chip/damage larger than 0.5mm tall, 'C' 1mm, 'F' otherwise. Not part of std chopping grade, will test baton-cut & chop16D nail - of course edge will suffers damages but by how much & mode?

I haven't order the steel yet, so feel free to chime in your opinions

For perspective of my background & current ht, here is my test of m398 66rc this morning. M398: https://www.alphaknifesupply.com/Pictures/Info/Steel/M398-DS.pdf. Also tested s90v 65rc, T15 68rc, 15V 69rc.

 

[shane45-1911]

here is my test of m398 66rc this morning. M398: Also tested s90v 65rc, T15 68rc, 15V 69rc.

I'm definitely no expert in the field of heat treating or knife making, but your HRC ratings seem a bit on the high side? I would think that you will see exaggerated chipping (versus rolling) at that hardness. I would much prefer my choppers to roll slightly rather than chip out and my personal preference would be around 59-60 HRC for a heavy duty chopper.

I also think that 20 DPS may be a bit acute for a chopper. I like 22ish DPS for my choppers. An extra couple of degrees per side goes a long way to maintaining edge integrity if chopping is your primary objective.

Regardless, looking forward to your tests and the outcomes.

 

[BluntCut MetalWorks]

I'm definitely no expert in the field of heat treating or knife making, but your HRC ratings seem a bit on the high side? I would think that you will see exaggerated chipping (versus rolling) at that hardness. I would much prefer my choppers to roll slightly rather than chip out and my personal preference would be around 59-60 HRC for a heavy duty chopper.

I also think that 20 DPS may be a bit acute for a chopper. I like 22ish DPS for my choppers. An extra couple of degrees per side goes a long way to maintaining edge integrity if chopping is your primary objective.

Regardless, looking forward to your tests and the outcomes.

Here is brutal test of steels at more reasonable hardness and only 2 are chipped (s45vn & elmax)

 

[shane45-1911]

Thanks - quite interesting.

 

[Twindog]

Should be interesting. S90V is not too far off of D2 or 10V in toughness, and people make choppers out of D2 -- although not that hard.

I often have to chop off encroaching branches on my road and trails, especially this time of year when the rainforest growth is explosive. Surprisingly, it's a challenge for most steels, largely because of sharp changes in the direction of the wood grain that can force an edge laterally while the blade if moving vertically. With less robust steels, I get rolling and deflections, but not many chips.

At 64 Rc, your blade would be resistant to rolling and deflections. And the edge should last a long time. I usually need a hardness of 60 Rc to keep the edge from rolling or denting. But I did crack and chip a blade in A8(mod) with this kind of chopping. That steel should be extremely tough (think Infi). But the heat treat was bad.

For S90V, I'd want a chore that isn't too challenging (like the nail or a pork bone), but one that would benefit from excellent edge wear.

For example, it might do well in the Bladesports cutting chamionships, where the toughness thing would be the 2x4 chop. It should hold an edge better than M4 or Vanadis 4E, giving it a better shot at the fine-cutting tasks in that sport.

Hope you already have the 2x4, because they are very expensive in this market. Loggers up my way are working Sundays.

Good luck.

 

[unwisefool]

I'm definitely no expert in the field of heat treating or knife making, but your HRC ratings seem a bit on the high side? I would think that you will see exaggerated chipping (versus rolling) at that hardness. I would much prefer my choppers to roll slightly rather than chip out and my personal preference would be around 59-60 HRC for a heavy duty chopper.

I also think that 20 DPS may be a bit acute for a chopper. I like 22ish DPS for my choppers. An extra couple of degrees per side goes a long way to maintaining edge integrity if chopping is your primary objective.

Regardless, looking forward to your tests and the outcomes.

You should probably read the crystal weaving thread on here. It goes into detail of his process. There are a lot of pictures and big words, it's pretty impressive.

Thread 'Heat Treatment - Crystal Weaving Foundation' https://www.bladeforums.com/threads/heat-treatment-crystal-weaving-foundation.1409721/

 

[BluntCut MetalWorks]

Should be interesting. S90V is not too far off of D2 or 10V in toughness, and people make choppers out of D2 -- although not that hard.

I often have to chop off encroaching branches on my road and trails, especially this time of year when the rainforest growth is explosive. Surprisingly, it's a challenge for most steels, largely because of sharp changes in the direction of the wood grain that can force an edge laterally while the blade if moving vertically. With less robust steels, I get rolling and deflections, but not many chips.

At 64 Rc, your blade would be resistant to rolling and deflections. And the edge should last a long time. I usually need a hardness of 60 Rc to keep the edge from rolling or denting. But I did crack and chip a blade in A8(mod) with this kind of chopping. That steel should be extremely tough (think Infi). But the heat treat was bad.

For S90V, I'd want a chore that isn't too challenging (like the nail or a pork bone), but one that would benefit from excellent edge wear.

For example, it might do well in the Bladesports cutting chamionships, where the toughness thing would be the 2x4 chop. It should hold an edge better than M4 or Vanadis 4E, giving it a better shot at the fine-cutting tasks in that sport.

Hope you already have the 2x4, because they are very expensive in this market. Loggers up my way are working Sundays.

Good luck.

Thanks.

Small dried hard branch can grab & pry the edge when it deflects away. Thin edge would fare poorly in this case. Similarly when part of the embedded edge steer away (lateral deflection) from apex line, which often result in a large half moon chip. This envisioned 64rc s90v would be fine for the first case but suffer the 2nd case like other low ductility chopper steels.

I've some fairly good condition used 2x4 to wood chipping test Perhaps you can find some old growth pine logs in Lake Crescent, then send to me for testing. Pine heartwood & red-knot are ridiculously hard, esp on low hardness sub 20 dps choppers.

I still have 64rc D2, 65rc D6, 65rc 10V, 65rc Niolox, .. choppers. Not sure these would do well against dried bone and lignum vitae wood. Will see how this 64rc s90v fare?

edit: just ordered enough s90v for making 2 choppers.

 

[patrickguignot]

Here is brutal test of steels at more reasonable hardness and only 2 are chipped (s45vn & elmax)

According to Larrin's standardized tests S45VN is at least as tough as S30V. Even marginally tougher.
But in your test S45VN chipped spectacularly and S30V didn't.
It's intriguing. Perhaps this should question the accuracy of your test?

 

[BluntCut MetalWorks]

According to Larrin's standardized tests S45VN is at least as tough as S30V. Even marginally tougher.
But in your test S45VN chipped spectacularly and S30V didn't.
It's intriguing. Perhaps this should question the accuracy of your test?

I've tested s45vn quite a few times before includes control ht. In all case, it is brittle and so as s30v control ht.
If 1095 performance according larrin's test result, it would've shatter in pieces, right? Well, it didn't nor niolox, etc.. in this cutting 60D (6.6mm diameter) annealed mild steel/nail.

 

[ferider]

Here is brutal test of steels at more reasonable hardness and only 2 are chipped (s45vn & elmax)

Very interesting. That CPM 154 @64 HRC is holding up well, amazing given it’s lack of popularity.

 

[BluntCut MetalWorks]

Very interesting. That CPM 154 @64 HRC is holding up well, amazing given it’s lack of popularity.

Indeed - I noticed, CPM154 & N690 did a lot better than my ht projection.

I already did a follow up ht (v5 tf 5,25|0.50) of 30 pieces, here are some steel/hrc: cpm154/64.5, n690/64 & n690 control ht/63(max control ht attainable hrc), magnacut/63;63.5 and magnacut control ht/62-64, m4/65, 1095/64, ... pending test. Did tested: 15v, t15, m398, s90v - only shown above m398 result of cutting 16d nail.

*side note*
Pardon my internal ht versioning (embedding protocol variables with hashed values). This s90v chopper (along with t15, s90v, 15v) will get a more complex HT 5 TF(https://en.wikipedia.org/wiki/Theta_function) vars: 8,10|5,17|2,25|0,25. It is a 72 hrs ht process. Bringing up this point because many of knifenuts & pros on this forum are well informed on performance of standard/control ht edges, please keep that in mind when comparing to my ht.

 

[patrickguignot]

I've tested s45vn quite a few times before includes control ht. In all case, it is brittle and so as s30v control ht.
If 1095 performance according larrin's test result, it would've shatter in pieces, right? Well, it didn't nor niolox, etc.. in this cutting 60D (6.6mm diameter) annealed mild steel/nail.

Your toughness test must be different (different failure mode) than the one used by Larrin.

 

[BluntCut MetalWorks]

S90V shipment will arrives in a few days. I just ordered a bar of CPM154 for making a 64rc chopper (jungle knife profile). Reason for deciding to make a CPM154 chopper because it performed extremely well in my latest test:

Depends on 63.5rc Magnacut .175" thick field knife performance on pending tests, with good result(most likely it will) I will try to acquire 1/4" thick magnacut to make 64rc Magnacut chopper. 63rc Magnacut test result above shows it has chopper potential.

Edit: CPM Magnacut 63 5rc Punch and Cut Mild Steel Bracket Test *warning: wind noise*

 

[BluntCut MetalWorks]

I decided to make this S90V chopper according to BladeSports' specs. It will be ht along with other blades in steels: 10V, 15V, T15, Magnacut

 

[BluntCut MetalWorks]

65rc S90V HT 5 TF 7,15,22.5 | 5,15,20 | 2,15,14 | 0,25
Sharpened with edgepro at 20dps, ~ 0.022" BET

Chops hard woods, pork rib bone and 16D nail.

Edge after hardwoods and bone

Edge after baton 16D nail

Edge after chopped 16D nail

16 minutes video

 

[JacksonKnives]

Looks like you're using idea geometry for that kind of cutting. Very interesting results! I tested S90V with lateral loading against a steel rod (mostly to see how it would perform in a kitchen knife with suitable slicing geometry) and 1mm chunks popped out at 5lb of load.

 

[BluntCut MetalWorks]

Looks like you're using idea geometry for that kind of cutting. Very interesting results! I tested S90V with lateral loading against a steel rod (mostly to see how it would perform in a kitchen knife with suitable slicing geometry) and 1mm chunks popped out at 5lb of load.

What hardness & edge geometry were your blade?

I ht-ed this blade (and quite a few other blades) along with chopper above. It will be a very thin slicer - plan edge geometry: 15dps, 0.007" behind edge thick... and it will face bone whittling test.

 

[JacksonKnives]

What hardness & edge geometry were your blade?

I ht-ed this blade (and quite a few other blades) along with chopper above. It will be a very thin slicer - plan edge geometry: 15dps, 0.007" behind edge thick... and it will face bone whittling test.

I was using a Spyderco mule honed down to 12DPS to compare against kitchen knives and give a baseline for "chippy" performance at that geometry. It probably had more thickness BTE, I'll look up the exact numbers on my old computer when I get a chance.

I'm not saying I doubt your results at all--the main thing I've learned through comparison of knives is that geometry is fundamental for getting the most from your edges. Also, slight modifications in test parameters can make a big difference in results, and you always need to re-establish your baseline comparison for a meaningful study of a parameter.

My first kitchen knife that actually went out of the shop was in 154CM at a sane hardness but ground much too thin, and it came back a year later with some scary (5mm) chips.

 

[BluntCut MetalWorks]

Agreed, 12dps bevel geometry is very thin for s90v (spyderco s90v mule 59.2rc).

I was using a Spyderco mule honed down to 12DPS to compare against kitchen knives and give a baseline for "chippy" performance at that geometry. It probably had more thickness BTE, I'll look up the exact numbers on my old computer when I get a chance.

I'm not saying I doubt your results at all--the main thing I've learned through comparison of knives is that geometry is fundamental for getting the most from your edges. Also, slight modifications in test parameters can make a big difference in results, and you always need to re-establish your baseline comparison for a meaningful study of a parameter.

My first kitchen knife that actually went out of the shop was in 154CM at a sane hardness but ground much too thin, and it came back a year later with some scary (5mm) chips.

Here is my (just finished) 7 minutes video - Testing 66rc s90v edge stability and damage mode by whittle dried pork rib bone and nail

EDIT: using triangle calculator ~0.25mm bevel face, 15dps = 0.13mm (0.005") behind edge thickness

Closeup image of edge:

 

[Twindog]

Those are really good results, Luong. I didn't know S90V could be that robust, much less at that hardness and geometry.