CPM REX 45 | Edge Performance

[ejames13]

Thanks for that analysis and testing!

Do you have a Cruwear blade you could test REX 45 against? I would really like to see how the two compare.

Yes, however I chose M4 because I felt the chemistry was closer and people have a better feel for how M4 behaves.

I really like the Para 3, it's very exciting that Spyderco has made it a flagship model with a huge variety of steels just like the PM2. I'll just keep building up a collection of para 3 for testing steels. Also it's just my favorite model, especially with a deep carry clip.

More testing when I get time.

Gut feeling, do you prefer REX45 or Cruwear, and why?

[Tucson Tom]

I was very glad to see this thread. M4 does seem like an ideal steel to compare Rex45 to given that Rex45 is basically M4 with a lot of cobalt added. I'll have to say that while I do very much like M4, the Rex45 seems to "have an edge" on it. No telling what it is, but it is pretty impressive stuff and certainly lives up to my hopes and expectations. Thanks for taking the time to provide this info.

Oh yes, what I would be curious to hear is how Rex45 compares to Maxamet, or even K390.

[Molle Ninja]

Re: Cruwear... Frankie (mentioned earlier in this thread, also the man behind Tactical Pteradactyl Knives) said that in his testing Cruwear is in a wholly different (better) league. Seems a little less-than-impressed about Rex45’s edge retention. Kind of a bummer, if true.

[Deadboxhero]

Thanks for that analysis and testing!

Do you have a Cruwear blade you could test REX 45 against? I would really like to see how the two compare.

Yes, however I chose M4 because I felt the chemistry was closer and people have a better feel for how M4 behaves.

I really like the Para 3, it's very exciting that Spyderco has made it a flagship model with a huge variety of steels just like the PM2. I'll just keep building up a collection of para 3 for testing steels. Also it's just my favorite model, especially with a deep carry clip.

More testing when I get time.

Gut feeling, do you prefer REX45 or Cruwear, and why?

Nah, too soon to say, I've sharpened it two times, I've sharpened Cruwear on various models and have made knives in Cruwear, so there is always a bias towards what you know.

Let's test more and see what Rex 45 can do.
I'm liking the steel for how easy it takes a keen edge and if your a Polished edge guy it should be a God send based on what I'm experiencing so fair.

Standby, got to fill some orders for stuff that makes money before I can goof off on knife testing :D

[ikaretababy]

Hi, thanks for the initial thoughts on this steel. still waiting on the USPS for the moment.

You answered a lengthy question of mine on youtube so thanks for the info and I'll certainly keep an eye on this thread.

[tomr]

Shawn,

Thanks for all you do for us. Your Youtube videos, and contributions here and at BF, are much appreciated.

Regards Rex 45, Ive a couple questions.

1. Why? That is, looking at the body of work around various steels, (most recently yours, Michael Christys and even Cedric & Ada for example), why should we buy this steel? What does it do that the others don't? Is this just another picket in a fence line?

2. Thinking about #1 above, comparing REX 45 to M4 infers where this stuff might fit in the continuum. Until delivery, hypothetical comparisons were with HAP40. I believe we've learned (or are learning), the importance of edge geometry - thickness behind the edge, apex angles, finish, etc. to blade performance. Spyderco's folding knives are a package. Between blades, handles and standoffs, to keep manufacturing variables under control, only so many things can change. HAP 40 is a laminated steel. The HAP 40 part, the stuff that cuts, is a thin layer sandwiched between 2 also thin outer layers of something else. Does that fact provide an edge (pun not intended), to HAP 40 were it to be compared to Rex 45 (do to it being REX45 all the way through) in edge geometry? Seems like the thickness behind the edge, of the stuff that cuts, could favor HAP 40. I doubt Spyderco modified overall dimensions to make the whole knife package work, they could of course have played a bit with spine to apex taper... a bit. Did they? Thoughts?

tomr

[Deadboxhero]

Shawn,

Thanks for all you do for us. Your Youtube videos, and contributions here and at BF, are much appreciated.

Regards Rex 45, Ive a couple questions.

1. Why? That is, looking at the body of work around various steels, (most recently yours, Michael Christys and even Cedric & Ada for example), why should we buy this steel? What does it do that the others don't? Is this just another picket in a fence line?

2. Thinking about #1 above, comparing REX 45 to M4 infers where this stuff might fit in the continuum. Until delivery, hypothetical comparisons were with HAP40. I believe we've learned (or are learning), the importance of edge geometry - thickness behind the edge, apex angles, finish, etc. to blade performance. Spyderco's folding knives are a package. Between blades, handles and standoffs, to keep manufacturing variables under control, only so many things can change. HAP 40 is a laminated steel. The HAP 40 part, the stuff that cuts, is a thin layer sandwiched between 2 also thin outer layers of something else. Does that fact provide an edge (pun not intended), to HAP 40 were it to be compared to Rex 45 (do to it being REX45 all the way through) in edge geometry? Seems like the thickness behind the edge, of the stuff that cuts, could favor HAP 40. I doubt Spyderco modified overall dimensions to make the whole knife package work, they could of course have played a bit with spine to apex taper... a bit. Did they? Thoughts?

tomr

Hi Tomr, I appreciate someone that just wants a pragmatic answer

1. Most pocket knife steels have a bias towards toothy edges because in the real world that's more of what accentuates the use folding knives. Rex 45 is showing to be unique in that has more of a bias towards those that like to geek out on polished push cutting edges that aren't as pragmatic but are more sporty.

By laymans terms Rex 45/Hap40 gets sharper, keener edges then some other steels, however this is untrue. All steels at decent hardness and heat treatment get sharper then we can ever possibly sharpen them too.

Micheal Christy is a great example at this since before his videos there was a belief that s110v could not take a very keen edge, which is wrong. Sharpening skill, techniques and tactics overcome all. People will just find REX 45 easier to get keener, whether they need that is all preference.

Its wonderful that Spyderco continues to try new things to really capture our imagination, curiosity and wonder. What a boring world to live in without people like Sal that strive to share different flavors; Vanilla and Chocolate get old :D

2. The difference in geometry between laminated hap40 and REX 45 is an irrelevant question. There is no inherent differences in geometry vs a laminated steel and non laminated steel. They are no thicker or thinner then the model made is made to be. Any geometry differences are the differences between a delica and a para 3, nothing more.

[Deadboxhero]

Give me some time to test more, I've never used Rex 45 before so I wanna do more testing to see what happens. Im just sharing what i've seen so far from sharpening and using for a few days. lets do some more destructive edge testing and rope cutting when I get time

[The Meat man]

Shawn, again thanks for sharing. I have no REX 45 and not really planning on it (too many other sprints), but I find all this of absorbing interest. Keep it coming! We really appreciate it.

[tomr]

Sean,
I had a hard time writing question #2. Not sure I was clear. Assuming all things are more or less equal from one Spyderco model to the next. Where then spine thickness and taper to apex are relative constants, could it be that the skinnier bit of HAP40 that protrudes from within its laminate, to form the apex makes it a bit slicier over what then must be the thicker side to side bit of REX 45 at its taper to apex? Or, too many other variables to say?
Tomr

[awa54]

Sean,
I had a hard time writing question #2. Not sure I was clear. Assuming all things are more or less equal from one Spyderco model to the next. Where then spine thickness and taper to apex are relative constants, could it be that the skinnier bit of HAP40 that protrudes from within its laminate, to form the apex makes it a bit slicier over what then must be the thicker side to side bit of REX 45 at its taper to apex? Or, too many other variables to say?
Tomr

Laminate blade stock is no different than homogenous blade stock dimensionally, it's just a slab composed of a three layer sandwich (soft/hard/soft), rather than one layer, so primary bevels are the same so long as Spyderco doesn't choose to alter the grind angle for a given production run.

My HAP40 Delica had a slightly thinner grind than the VG-10 Delicas I've seen... Not because it was required, but probably because Sal & Co. felt that HAP40 could support a more acute edge grind than VG-10, or buyers of that Sprint would appreciate a thinner grind more than increased resistance to hard use/abuse.

Let the grind suit the strengths of the steel!

[tomr]

This was my bad. Should've looked before I wrote. Shawn's recent video https://youtu.be/9m-Ma4_BRaw, clears it up. The outer laminate layers are ground away well before/above the the primary bevel's taper to the apex.

[GarageBoy]

What's the golden standard steel for burrs that break off cleanly?

I thought m4 had decent Apex stability and would hold thin, fine edges well

[Bill1170]

What's the golden standard steel for burrs that break off cleanly?

I thought m4 had decent Apex stability and would hold thin, fine edges well

ZDP is my gold standard for a steel that the burr comes off cleanly. It also works very well with a thin polished edge.

[EngDevGr3]

Has anyone seen any testing on Rex 45 yet? I have not been able to find any cut tests as of yet.

[Deadboxhero]

CPM Rex 45 is more stable at the edge then Spydercos CPM M4

Rex took less damage.


Rex 45


M4


So I went back and torqued on Rex 45 more



Still less damage.

[Woodpuppy]

The M4 must have been weakened by the DLC :p

[ikaretababy]

CPM Rex 45 is more stable at the edge then Spydercos CPM M4

Rex took less damage.


Rex 45


M4


So I went back and torqued on Rex 45 more



Still less damage.

What's the golden standard steel for burrs that break off cleanly?

I thought m4 had decent Apex stability and would hold thin, fine edges well

ZDP is my gold standard for a steel that the burr comes off cleanly. It also works very well with a thin polished edge.

Interesting to mention ZDP as I was sharpening my REX45 PM2 and seemed it was very comparable to ZDP-189 in feel. Granted, I don't have near as much experience with M4 as compared to ZDP. I'm sure the comparison to M4 is more valid since they are in the same league and have a lot of chemistry in common--but my limited anecdotal experience so far is that it sharpens similar to ZDP-18. I didn't get a lot of feedback on shaptons which was expected. With ZDP-189 I always have trouble feeling the edge on my finger pads until I get to my highest grit stone and add diamond spray. From there it always develops an edge that is very fine by my standards and ready for stropping.

I sharpened my REX45 para twice because I couldn't get the deep scratches out of the area around the heel where the factory edge gets noticeably thick. The second time I followed my usual "recipe" for sharpening ZDP and it worked out really well. Still having trouble with the heel and I will probably add the usual notch there unless someone has a good tip for that problem. This is not a knock on the finish or design of the knife by the way. For now its too fussy for my present level of skill and patience.

I don't think I'll sharpen the steel again until it gets dull from use. Actually, I know I won't because theres a drawer full of dull knives that has been growing thanks to the endless stream of exotic sprints spyderco keeps releasing. First opinion of the steel is that its very promising with the potential to be a home run if it has edge retention similar to other steels in its league. Very cool.

If I could find calipers I would confirm this myself but the grind on my PM2 feels thinner than the grinds on either my m4 or 52100 PM2s. I tried holding them next to each other at a bunch of angle but I can't tell if I can see a difference or not. It really feels thinner though. Does Spyderco do that? I assume thats too complex to do when all your tolerances and calculations for tooling are factored in but it REALLY feels thinner to me.

Thanks BBB for the toughness testing video. crazy results for both steels imo. The way the edge on the REX45 looked after that is unbelievable though. Did not expect that based on the sound of that brass squeaking. What a horrible sound.

[razorsharp]

Starting to lose track of all your different usernames BBB , lol. Said it everywhere else, but thanks for the comparisons!

[mb1]

Shawn, I have short-ish list of other steels I'd like you to do that brass test on...just for comparison. :eek: :cool: :spyder:

That's pretty impressive on the Rex 45. Probably much easier to standardize edge retention testing (with rope cuts, linear ft of cardboard, etc) than toughness testing. Hard to quantify the force and lateral stress you were inducing I know, but I thought that gave a good comparison of gouged brass vs edge damage. And thanks for not asking me to volunteer my inventory! lol