- Joined
- Mar 26, 2011
- Messages
- 647
Good day all,
I recently acquired one of Farid's custom K2 folders in REX121. For those unclear about REX121:
CPM REX-121 CHEMICAL COMPOSITION
Carbon 3.40 %
Chromium 4.00 %
Vanadium 9.50 %
Tungsten 10.00 %
Cobalt 9.00 %
Molybdenum 5.00 %
Farid Heat Treats this to Rc 68-70. 70 at the cutting edge and 68 at the thicker parts of the blade. It is my understanding that the thick stock used (4+ mm) was to prevent warping during HT that was seen on thinner stock. Farid or anyone else, please correct me if I'm wrong.
Initial Impressions and Sharpening:
This thing is a beefy and huge. After chatting with Farid, it seems this steel would be well suited to a convex grind. So when I put a convex bevel on this blade, I just couldn't stop grinding! I'm a believer of Murray Carter's advice on sharpening...you can't just sharpen the main bevel...you have to sharpen the whole blade! Well this may or may not be what he really meant, but here we are. After wearing down many of my stones and purchasing a new DMT diamond X-Coarse/Coarse plate, and going through lots of sand paper...I finally got my blade just about where I want it. It is also shaving sharp. I'm still trying to figure out the best finish on this blade but so far, I think finer = better. My apologies to Farid, I inadvertently ground away your "FARID" logo on the secondary bevel of the blade. I verified the angle of the bevel (per my Edge Pro) and it was right about 15 deg/side right at the cutting edge (since it was convexed). Lucky me since I did not want to regrind this steel!
Also, the steel is LUCKILY tougher than I thought. Like a dummy, I accidentally dropped this blade (open) on my tile floor and fortunately it did not break. It did land on the cutting edge and dinged up the blade a LITTLE...but my floor took on more damage.
So here are my pics of my handiwork:
After sharpening, I realized that I still probably haven't mastered the finish on this steel. I can get the knife arm hair shaving sharp, but not hair whittling sharp (may be in part because of the angle, but at 15 deg/side, I can get M390 and S90V hair whittling sharp).
Steel Performance:
So now...the testing. I couldn't wait to test this steel since, let's face it, that's what this folder is all about! In my testing, I generally cut 5/8" manila rope on a wood surface and cut until I can no longer slice phone book paper cleanly. To me, if my knife cannot slice phone book paper, it is not sharp. I've done this test on other premium steels like S90V (Spyderco Military), M390 (Spyderco PM2), CTS-204P (Microtech Socom Elite), M4 (Benchmade Rift Forum knife), 154CM (Benchmade Rift).
I cut, and cut, and cut more. My hands hurt even though I was wearing gloves. My wrists got tired and honestly...I think I realized just how old I'm getting. Anyway this is what I found:
Since I did not want this test to go into a multi-day affair, I called it quits. I cut a lot of rope, a large, beefy cardboard box, and my blade is still quite sharp. Here are some pics after the cutting:
After the cutting, the blade had ZERO chips, rolls, flattening or other damage. It was simply less sharp. I dragged my finger nail across the edge and inspected the edge with a loop...and found nothing. In fact, the only thing I saw were my small imperfections from sharpening just above the cutting edge. I also noticed that there were no scratches on the blade from my cutting (something that I cannot claim on any of the other aforementioned premium steels). As before the test, there was no blade play and lockup remained early after all the cutting. This blade is thick stock (I think 4+ mm) with a saber grind so it does not glide through material like say...my BM Rift. Rope cutting was harder than usual as was the cardboard cutting, adding to my fatigue.
Even though I did not "finish" the test, I am happy with the results. I may one day try to finish this test until it no longer slices phone book paper...but for now, I'm content with the knowledge that this knife steel far outperforms anything I've owned previously. The steel has proven to be tough in its current geometry (tough enough to survive a drop on tile floor and survive the cut testing without any damage) and edge retention is incredible.
Here is a slick thing about REX121 (and Farid's HT of it): After all this testing, re-sharpening was a breeze. I only required a simple progression of sandpaper and strops to bring it back to arm hair shaving sharp.
Ergonomics and Comfort:
This is probably not this folder's strength. This knife is not the most comfortable out there. The handles are a bit thin and some hot spots developed after the considerable amount of cutting I did, even with gloves on. However, this translates nicely into a fairly thin folder that is surprisingly easy to carry. Not bad for a 4.6 inch monster! I can easily carry this IWB at 4 o'clock, no problems.
Overall Fit/Finish and Design:
It's a cool design that emphasizes function over form. It's a folder, it works and it's simple. It packs a maximum amount of blade for the handle size. Blade centering is perfect. I will say the "as rolled" finish on the flats make for an unusual feel of the detente skidding over the uneven surface as the blade is opened/closed. The size of this blade makes it unusable in an office environment. I love large knives...this one fits the bill! However, maybe we can convince Farid to make me a 3.6" version of this bad boy in REX121 in a wharncliff or reverse tanto. Then we sport it around town more easily.
Conclusion:
I don't know how many opportunities a knife knut will get to obtain and test a super premium steel like REX121. So when this knife came up, I had to have it. The edge retention is fantastic (may even be better if I re-test), the toughness is better than I expected (for the composition and hardness) and actually, the corrosion resistance has not been bad at all. However, I carry Super Blue and M4, so I am used to EDCing rusting steels.
I'm not sure what the future brings in terms of steels, but I would be surprised if anything surpassed REX121 for edge retention in the near (or even farther out) future. I also don't know if other entities will produce this steel at this hardness (Rc 68-70) for a knife.
Thank you FARID for making an excellent product! What a privilege it is to own, test and use a super premium steel in a tough, durable folder!
I recently acquired one of Farid's custom K2 folders in REX121. For those unclear about REX121:
CPM REX-121 CHEMICAL COMPOSITION
Carbon 3.40 %
Chromium 4.00 %
Vanadium 9.50 %
Tungsten 10.00 %
Cobalt 9.00 %
Molybdenum 5.00 %
Farid Heat Treats this to Rc 68-70. 70 at the cutting edge and 68 at the thicker parts of the blade. It is my understanding that the thick stock used (4+ mm) was to prevent warping during HT that was seen on thinner stock. Farid or anyone else, please correct me if I'm wrong.
Initial Impressions and Sharpening:
This thing is a beefy and huge. After chatting with Farid, it seems this steel would be well suited to a convex grind. So when I put a convex bevel on this blade, I just couldn't stop grinding! I'm a believer of Murray Carter's advice on sharpening...you can't just sharpen the main bevel...you have to sharpen the whole blade! Well this may or may not be what he really meant, but here we are. After wearing down many of my stones and purchasing a new DMT diamond X-Coarse/Coarse plate, and going through lots of sand paper...I finally got my blade just about where I want it. It is also shaving sharp. I'm still trying to figure out the best finish on this blade but so far, I think finer = better. My apologies to Farid, I inadvertently ground away your "FARID" logo on the secondary bevel of the blade. I verified the angle of the bevel (per my Edge Pro) and it was right about 15 deg/side right at the cutting edge (since it was convexed). Lucky me since I did not want to regrind this steel!
Also, the steel is LUCKILY tougher than I thought. Like a dummy, I accidentally dropped this blade (open) on my tile floor and fortunately it did not break. It did land on the cutting edge and dinged up the blade a LITTLE...but my floor took on more damage.
So here are my pics of my handiwork:
After sharpening, I realized that I still probably haven't mastered the finish on this steel. I can get the knife arm hair shaving sharp, but not hair whittling sharp (may be in part because of the angle, but at 15 deg/side, I can get M390 and S90V hair whittling sharp).
Steel Performance:
So now...the testing. I couldn't wait to test this steel since, let's face it, that's what this folder is all about! In my testing, I generally cut 5/8" manila rope on a wood surface and cut until I can no longer slice phone book paper cleanly. To me, if my knife cannot slice phone book paper, it is not sharp. I've done this test on other premium steels like S90V (Spyderco Military), M390 (Spyderco PM2), CTS-204P (Microtech Socom Elite), M4 (Benchmade Rift Forum knife), 154CM (Benchmade Rift).
I cut, and cut, and cut more. My hands hurt even though I was wearing gloves. My wrists got tired and honestly...I think I realized just how old I'm getting. Anyway this is what I found:
- I cut the 5/8" manila rope 412 times (roughly 3x M390/S90V/M4). Honestly, I ran out of rope hence the odd number. The REX121 still cut phone book paper. The edge was definitely not as sharp as the beginning...but it was still cutting phone book paper. By non-knife people's standard, this knife was still sharp.
- Since I ran out of rope, I dug through my garage for some cardboard. I found an office moving box. They are pretty beefy so I felt I could wear down my blade with it. I then cut it into strips. Towards the end of the cutting, my triceps were starting to cramp so I think it was affecting my cutting...either that or my blade was actually dulling. There was some tearing so I felt I may have degraded the blade to where it would no longer cut phone book paper. However, after wiping the blade off quickly (not stropping...just a quick brush off my pants), the blade still cut phone book paper.
Since I did not want this test to go into a multi-day affair, I called it quits. I cut a lot of rope, a large, beefy cardboard box, and my blade is still quite sharp. Here are some pics after the cutting:
After the cutting, the blade had ZERO chips, rolls, flattening or other damage. It was simply less sharp. I dragged my finger nail across the edge and inspected the edge with a loop...and found nothing. In fact, the only thing I saw were my small imperfections from sharpening just above the cutting edge. I also noticed that there were no scratches on the blade from my cutting (something that I cannot claim on any of the other aforementioned premium steels). As before the test, there was no blade play and lockup remained early after all the cutting. This blade is thick stock (I think 4+ mm) with a saber grind so it does not glide through material like say...my BM Rift. Rope cutting was harder than usual as was the cardboard cutting, adding to my fatigue.
Even though I did not "finish" the test, I am happy with the results. I may one day try to finish this test until it no longer slices phone book paper...but for now, I'm content with the knowledge that this knife steel far outperforms anything I've owned previously. The steel has proven to be tough in its current geometry (tough enough to survive a drop on tile floor and survive the cut testing without any damage) and edge retention is incredible.
Here is a slick thing about REX121 (and Farid's HT of it): After all this testing, re-sharpening was a breeze. I only required a simple progression of sandpaper and strops to bring it back to arm hair shaving sharp.
Ergonomics and Comfort:
This is probably not this folder's strength. This knife is not the most comfortable out there. The handles are a bit thin and some hot spots developed after the considerable amount of cutting I did, even with gloves on. However, this translates nicely into a fairly thin folder that is surprisingly easy to carry. Not bad for a 4.6 inch monster! I can easily carry this IWB at 4 o'clock, no problems.
Overall Fit/Finish and Design:
It's a cool design that emphasizes function over form. It's a folder, it works and it's simple. It packs a maximum amount of blade for the handle size. Blade centering is perfect. I will say the "as rolled" finish on the flats make for an unusual feel of the detente skidding over the uneven surface as the blade is opened/closed. The size of this blade makes it unusable in an office environment. I love large knives...this one fits the bill! However, maybe we can convince Farid to make me a 3.6" version of this bad boy in REX121 in a wharncliff or reverse tanto. Then we sport it around town more easily.
Conclusion:
I don't know how many opportunities a knife knut will get to obtain and test a super premium steel like REX121. So when this knife came up, I had to have it. The edge retention is fantastic (may even be better if I re-test), the toughness is better than I expected (for the composition and hardness) and actually, the corrosion resistance has not been bad at all. However, I carry Super Blue and M4, so I am used to EDCing rusting steels.
I'm not sure what the future brings in terms of steels, but I would be surprised if anything surpassed REX121 for edge retention in the near (or even farther out) future. I also don't know if other entities will produce this steel at this hardness (Rc 68-70) for a knife.
Thank you FARID for making an excellent product! What a privilege it is to own, test and use a super premium steel in a tough, durable folder!
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