Anyone here with gayle Bradley with date code JJ?

[Slash]

My Benchmade 760 Lum Tanto(one of my favorite knives) with M4 that I've been using for over a year now never chiped or rolled the edge and I beat the crap out of that knife...can you say pry bar? So, I can honestly tell you it's NOT the steel. I've chopped tree limbs, dug holes in rock filled dirt, twisted the blade in particle board to bore out a hole some more. **** I've even hammered the blade like a chisel to chip out the edge of hardwood on a kitchen cabinet to notch the ear so I can run my crown molding flush with the side panel, etc...

Not sure what Benchmade did in comparision to Spyderco as far as heat treat is concerned because I don't have a GB to compare it to.

M4 is a very tough steel that's holds a great working edge.

[hunterseeker5]

Lets remember that CPM M4 is the steel of choice for bladesports, its no slouch. This rolling and chipping may be caused by a variety of things, but it is NOT normal.

Lets also remember that Ankerson's comparison chart is not destiny. M4 ranked in category 2, but so did M390 and S90V in some of his tests. It may well rank in category 1 if he tested another M4 knife. Heat treat, edge treatment, edge geometry, overall blade geometry, etc will ALL affect the test moving steels between categories. They are not absolute. Lets also remember that this is one specific type of test which favors a specific narrow band in the steel performance spectrum. Don't get me wrong I'm both very thankful for Ankerson's work and am not in any way discrediting it, but I think he'd agree that his test results aren't intended to be the final word on a steel. Lets just remember that the only blade competition in the world consistently puts M4 at the top of the pile, so its absolutely a match for the best out there. The performance issues discussed here are not normal.

[Zencowboy]

I emailed him, what was the verdict of mailing his Gayle Bradley M4 into Spyderco and he promptly emailed back kindly/warm and detailed (his last post on this topic was April 2011). I asked him if was alright to post his email to me here and he said it would be fine, so here it is below:

"Well Spyderco exceeded expectations in all respects. They tested my knife and found the hardness to be 63-64 Rockwell C. They tested 5 places along both the edge and spine. They also did a CATRA test and the knife passed. Then to top it all off, they REPLACED my knife (now with 5 very noticeable conical indentations) with a brand new one. How great is that?

Ok, that's the good part of the story. The other half is that I am still quite disappointed in M4 steel. It holds an edge poorly indeed. I have now tested it in comparison to many other knives and it just does not hold an edge well. I can put a shaving sharp edge on it with either my Lanskey system or my Japanese water stones. I am putting a 35 deg. included edge with the Lansky and about the same with the water stones. The steel does take a sharp edge with some practice and care. But, it just will not hold that edge. After cutting up just one medium size single wall corrugated box it will no longer shave. And, I am not talking about cutting it into a hundred little pieces. I am talking about cutting it into perhaps 10 pieces to put into the recycling box. After that very minimal work, not only is the shaving edge gone, but it will no longer cleanly cut newspaper or phone book paper.

Surprisingly, given the hardness, it does not take but a little stropping on a .25 micron Mono-crystalline diamond loaded hard backed strop to put a fairly good (working edge) back on. But, this should not be required. Good grief, I have 420HC that does better than this.

So, from my perspective (this is my only M4 knife) I have to assume there is nothing bad Spyderco is doing, and that the steel is the problem. I used to think it was my sharpening skills, but I no longer belief this is the case. Using the same sharpening equipment and technique, I am sharpening other 'super steels' and have no edge holding problems with the single exception of M4.

So, for the near term future, no more M4 for me.

Sorry for such a long response, but I wanted to give you the complete scoop at lest from my perspective. If you have anything to add re the GB or M4 I would certainly be interested in your thoughts.

Sincerely,

Bruce Buchanan"

[Brock O Lee]

Thanks Zencowboy, and BTB...

This is very interesting. It seems to correspond to the OP's youtube video, and my (and others) experience.

I am surprised to hear that the RC was measured high at 63-64 for this 'problem' case.

Should M4 keep a shaving edge long, or does it loose it quickly and keep a working edge long?

I dont mind a working edge, but what worried me initially was to see flat spots (easily visible to the naked eye), after only a few cuts on cardboard. :confused:

[hunterseeker5]

Wow again top notch CS from Spyderco. Impressive.

I'm really having trouble figuring all this out, but there must be a reason. If we eliminate the possibility that the users are just "crazy" what are we left with as possibilities? We know the steel is hard enough, and that in fact the steel can cut well because it performed in the CATRA test. Well one is the sharpening method used could be the source of the problems. There are two user visible things which might support this. The first is that if the factory edge lasted significantly longer than the edges produced by subsequent sharpening. The other is that both users, IIRC, used a single side sharpening method which holds a consistent angle like the lansky, edge pro, etc. Those systems are great because they're capable of holding a very consistent angle, but they can also quite nicely create a burr which is parallel to the edge and not particularly evident when you start cutting but which causes the edge to quickly degrade. Lighter strokes and more frequent alternations between sides followed by a more extensive free-hand stropping when you're done might alleviate this.

Its a shame CTS just sold his instead of pursuing the problem because I'd be interested to see, if we passed his knife around, whether we all would have issues with it or if some of us are either too oblivious to notice the problem or have/do something different which prevents it from appearing.

[Blerv]

It's a edge resistant high speed tool steel. Period.

No it's not s90v but few things are. It's a tough steel comparatively though. That's what Spyderco lists under the Gayle Bradley product description, not that it will cut the fabric of time and still shave a baby chinchilla.

Everyone has to pick the right product for them but relative comparisons are important to keep. Saying "it rolls easy" or "doesn't hold an edge" means nothing without "compared to _____ under these controlled circumstances_______..". Even these as hunter pointed out are difficult because human interaction generally messes with results (ie nobody is perfect) and the sample tested is one or two instead of dozens or even hundreds.

YMMV but fact is tougher to prove than a few Internet opinions. Especially when the steel in rolling question rc's at around 64.

[Brock O Lee]

Wow again top notch CS from Spyderco. Impressive.

Agreed!

The first is that if the factory edge lasted significantly longer than the edges produced by subsequent sharpening.

My factory edge had the problem. After I re-profiled to 30 deg back and 40 deg micro bevel and removed the burr on the ceramic, it performed better.

they can also quite nicely create a burr which is parallel to the edge and not particularly evident when you start cutting but which causes the edge to quickly degrade

I hear you, but at the time I was sure that it did not have a burr. Since the factory edge had a flat spot straight out of the box, I honed it on the 1200 grit Edge Pro ceramic, like I always do to maintain an edge/remove small flat spots.

When I hone, I usually do 3 passes per side, 2 passes per side, one pass per side, inspect for flat spots by shining a light on the edge. I'm not sure how a burr could survive a honing on a ceramic?

The only possible sharpening related issue I can think of is that M4, because of its increased toughness, holds a much more stubborn burr than other steels, and that it needs more work to remove it. Can someone maybe answer this?

[hunterseeker5]

The only possible sharpening related issue I can think of is that M4, because of its increased toughness, holds a much more stubborn burr than other steels, and that it needs more work to remove it. Can someone maybe answer this?

This is actually exactly what I was thinking. I did notice in my sharpening that, despite being quite hard, it was taking quite a burr. I normally scrub an edge down quickly working one side at a time until I get to the bevel I want, but when I work up through the grits I alternate sides with every stroke. The result holds an edge as well as anything else:


One other thing about edge retention I'd like to bring up quickly here. The high carbon content and high hardness of ZDP 189 should in theory give it better wear resistance than S90v (please correct me if I'm wrong) but we normally see better edge retention in S90v and my theory is thats caused by the edge microchipping on ZDP not because of a lower hardness or carbide volume. Similarly in bladesports cutting competitions people occasionally use S90v, among others, but M4 dominates. Why? This gets back to blerv's point of edge retention being relative. I'm not as quick to label S90v as having "superior" edge retention because in some cutting tasks it clearly doesn't match M4, and vice versa. When you get to super steels the "universal superiorities" break down. This is why the issues with M4 were so surprising to me. Having two knives in it (both spyders) I found it to be quite a formidable steel which would impress at all levels, being a super steel after all, but particularly when it comes to resisting chipping and edge deformation. Its hearing that which perked my ears up.

[Brock O Lee]

Thanks for the advice Hunter...

I'm still not convinced the issue is caused by a burr , but I will keep this in mind the next time I sharpen it. If the solution is this simple, then we are all winners here :)

[hunterseeker5]

What else can cause a remarkably tough wear resistant steel, famous for its ability to be used with thin edges, to present with micro-chips and edge damage after relatively light cutting work when hardness and presumably factory sharpening produce normal results? The best guess I have is sharpening method resulting in a plastic deformation at the edge. Its all I've got. :P If you can sharpen away your troubles...... :P

[DeathBySnooSnoo]

One other thing about edge retention I'd like to bring up quickly here. The high carbon content and high hardness of ZDP 189 should in theory give it better wear resistance than S90v (please correct me if I'm wrong) but we normally see better edge retention in S90v and my theory is thats caused by the edge microchipping on ZDP not because of a lower hardness or carbide volume. Similarly in bladesports cutting competitions people occasionally use S90v, among others, but M4 dominates. Why? This gets back to blerv's point of edge retention being relative. I'm not as quick to label S90v as having "superior" edge retention because in some cutting tasks it clearly doesn't match M4, and vice versa. When you get to super steels the "universal superiorities" break down. This is why the issues with M4 were so surprising to me. Having two knives in it (both spyders) I found it to be quite a formidable steel which would impress at all levels, being a super steel after all, but particularly when it comes to resisting chipping and edge deformation. Its hearing that which perked my ears up.

I could be wrong and I am sure that one of the people with much more knowledge than me can chime in here...but I think that S90V has better edge retention than ZDP due to not only the size of carbides but also the amount and the even distribution of them. Also, the other elements in the steel that increase the wear resistance and therefore push S90V to higher levels.

[CrimsonTideShooter]

What else can cause a remarkably tough wear resistant steel, famous for its ability to be used with thin edges, to present with micro-chips and edge damage after relatively light cutting work when hardness and presumably factory sharpening produce normal results? The best guess I have is sharpening method resulting in a plastic deformation at the edge. Its all I've got. :P If you can sharpen away your troubles...... :P

I ended up selling the two GBs that I made the thread about. The ones that I replaced them with are perfect, and perform VERY well.

That rules out a sharpening defect. Since I sharpened both sets of GBs the same way. Also, I am VERY adept at sharpening, and I can detect a burr even at 10,000 grit without magnification. There was no burr to speak of, and on my two samples the damage was visible.

On the new knives, I can cut like 10x the amount of cardboard (same type) without any edge damage at all. Still shaves hair cleanly after. :)

[HighDesertSpyder]

CTS,
Can we please get the date code on your 2 new Bradleys please and thank-you... off to the man cave to check the date code on mine. :eek:

[CrimsonTideShooter]

CTS,
Can we please get the date code on your 2 new Bradleys please and thank-you... off to the man cave to check the date code on mine. :eek:

The two new ones are GK. Bought from my local dealer right after he got them in a a couple months ago. :)

[HighDesertSpyder]

The two new ones are GK. Bought from my local dealer right after he got them in a a couple months ago. :)

Perfect, I can assume, correctly or otherwise, that mine also being a GK, should be fine. :spyder:
Thanks CTS

[hunterseeker5]

That rules out a sharpening defect. Since I sharpened both sets of GBs the same way. Also, I am VERY adept at sharpening, and I can detect a burr even at 10,000 grit without magnification. There was no burr to speak of, and on my two samples the damage was visible.

Well I guess this leaves me to ask what your theory is for the lousy performance you experienced?

[CrimsonTideShooter]

Well I guess this leaves me to ask what your theory is for the lousy performance you experienced?

Since both of the poor performers were date coded JJ, and both were sharpened the exact same way, and both performed in the exact same way - I can only assume that the JJ batch of blades were softer than intended.

Of course this is only conjecture since I didn't send the knives in to be tested, but I do a LOT of cutting tests on my YouTube channel, so I am fairly confident that I can recognize an under-performing steel. I especially feel this since I have tested the new knives in the exact same way with vastly different results. :)

I do want to say that with these knives I didn't experience any sort of weird edge failure or anything like that. I experience plain old rolling, and just plain old dulling. What was odd was how fast it happened. In just a few cuts the edge would be so dull that it could not slice paper. Cold Steel's AUS8 performed MUCH better than that.

Sometimes I wish that I had sent them in, but I got too good of a deal to pass up with the two new ones.

[rg02]

wheew! my GB is coded GK :D

[Truckie453]

Please excuse this newbie question, but where/how do I find the date code on my GB?

[Alchemy1]

I have 2 GK's as well. Look on the end of the box w/ the sticker. It will be on there.