Misc. edge testing

C

Cliff Stamp

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The following link is a to a cutting test on several grinds (hollow, flat, sabre) with several steels (D2, M2, 5160, 440A/425), with several edge finishes (polished, coarse, serrated). The material being cut included soft fabrics, hard plastics, aluminum and dirt.

<a href="http://www.physics.mun.ca:80/~sstamp/knives/edge_testing.html">Cutting performance (Buck / Benchmade / Cold Steel / HI / Custom)
</a>

-Cliff
 
Cliff:
Interesting site, lots of info about grinds, finishes, etc. We use a polished convex edge on the D-2 blade of the Uluchet. Just touched one up for a search and rescue team member, he'd chopped 150 dry pine branches before the edge started to shine and that was only about a one inch section.

------------------
P.J.
YES,it is sharp, just keep your fingers out of the way!
www.silverstar.com/turnermfg


 
Cliff --

Fantastically good article! A textbook demo on blade geometry, steels, and grits. You mention roughing up the recurve on your D-2 hunter. Just to be clear, are you saying this hunter is recurved, or did you mean the belly?

Joe
jat@cup.hp.com
 
Very good article, Cliff. I can't wait till you get the MD tusk to test it out.
 
The edge on the custom is convex and Mel Sorg (the maker) prefers that over a v-grind. I can see how it might be more durable but I don't see why it would slice better unless that sharp transition point on the v-grind provides high resistance/drag. In any case the performance is very high so even if I can't really see why I am pleased with it. I might put a v-grind on it and do some testing and then compare (just don't tell Mel I am mangling the nice edge he sent me).

Joe its recurved like the Vaquero only much much slighter. I should not really be calling it a drop point hunter but that's what the design started off from basically. I have pictures of it with the other knives and will eventually scan them. About the design, I asked Mel to put in a slight recurve as I have 3 similar knives coming and I wanted to covered a lot of ground with contrasting blade geometries.

Cobalt, should be in about a week.

By the way the one interesting thing that surprised me was the 600 grit finished Buck outlasting the 1200 grit polished one. I always assumed that the continuous edge on the 1200 grit finish would be much more durable than all the little teeth on the 600 grit. It actually isn't when you are slicing on abrasive/hard material. I still am not totally sure why, I think its a combination of all the slipping of the polished blade and the fact that a microserrated blade will slice better than a plain edge that is similarly distorted (the teeth will still bite in).

Anyone wanting an indepth discussion about the knife aspects discussed in the above (grit finishes, grinds etc.) just check out Joe's faq's.

-Cliff
 
Cliff,
You're killing me here....600 grit..... v-bevel.... next thing you know you'll be hammering it through railroad spikes ;-)

BTW, that convex edge has a 400 grit finish, sorta. Well, it started out as a 400 grit 2 x 42" sanding belt, and once they get worn almost smooth I use them for sharpening. Even that tiny, final convex edge took about five minutes to burnish on there a bit at a time.

madpoet
 
Mel, that's next week.
smile.gif


Ah, I was curious as to what you used to get the final finish, I meant to ask you about that. Its a very high polish, for comparasion its greater than the 1200 grit DMT stone will leave.

-Cliff
 
Note that there is little difference seen in the above link between the often claimed ultra edge holding metals like 440V and Stellite and regular ATS-34. If you assume the numbers could be off by say 2 cuts which is not unreasonable then you could be only talking about a 30-35% loss. And with the D2 only 10-15%. That is no where near the claims being made by people working with the CPM and Talonite/Stellite. For example CPM claims 440V has almost 10 times the wear resistance of D2 tempered to 59 RC.

I will be getting a Talonite and CPM knife soon, will be interesting to see how they compare with each other as well as some of the more common steels.

-Cliff
 
I was also surprized at the results the first time I read that test. I tend to beleive it more so than some metel chart though.
I think that test really shows 2 things. First all those steels hold a edge well if heat treated right. Secondly blade profile has alot to do with how a knife will cut.
 
EXCELLENT, Cliff. For a couple of years I've been beating my head against the wall trying to tell folks that in my tests coarse edges and either convex or flat grinds simply blow away the competition. As far as I know, you and Joe Talmadge are the only folks that have ever taken the time to see if I'm full of it or not. Everybody else just assumes that they know that coarse edges won't cut or something.

Try stopping at about 300-325 grit. Where things get really interesting is trying a worn 180 grit belt sanded edge against whatever else you like. ;-) ;-) If you do it right, it'll miserably fail the stupid shaving tests, but you probably don't want to be running your thumb down the edge. ;-)

I DO think there is much merit in matching the grit strategy to the particular blade shape, steel and potential use, but I don't obsess about it. It's just something to remember that not all alloys will take a decent coarse edge.

Another really, really interesting and useful edge can be had on most carbon steels under about 59-60 Rc with nothing but a really coarse mill bastard file. The files don't always work all that great on some types of stainless, but on high carbon steels you can get an edge that you simply have to experience to believe. Just resist the temptation to polish that rough feeling edge. It's at it's best fresh off the file. ;-)

Cliff, do you have a convex A2 blade like a BJ Trailguide? For some reason, they seem to me to be amongst the most awesome factory edges that I've ever experienced. Far better the the Boye Basic III in dendritic 440C and that's saying something. If you play around with the factory convex edge and wind up duplicating the factory rolled edge with a 325 (blue) DMT bench hone, you'll have an edge that may actually be the penultimate edge for rope, cardboard, many tough fabrics etc. (Don't know what the ultimate is. ;-)

Keep up the good work.
mps
 
Thanks for the comments Mike, while I have heard great things about A2 in terms of toughness you are the first person to comment on its cutting ability - performance over Boye's is very strong indeed. Have you any experience with L6?

In terms of using a file, yeah, you get awesome performance on slicing. In fact all my kitchen knives are sharpened on a butchers steel, and they are all soft enough to take that ragged but high performance edge. No problem cutting on hard crusty bread here.

Most of the people I know who use knives as part of their work perfer that agressive edge. The only ones who don't are the woodcarvers who need the ultra polished edge that is needed for fine push cutting.

Note on the above tests. After being disappointed by the Vaquero's ability to hold the serrations I took them off. Now I have a nice flat ground Vaquero with a plain edge left nice and coarse that (to quote Steve) cuts like stink.

Pics coming eventually.

-Cliff

[This message has been edited by Cliff Stamp (edited 14 March 1999).]
 
Cliff; damn good thread. I had no idea there were tests of edge holding out there. Would you do me a favor, and bring your info over to the thread I started on the General Forum (Blade Discussion Forum), New Alloys; hot or hype (or something like that).

Our intent is to compare any and all ferrous and non ferrous alloys; we have CPM's metallurgist, and a Materials engineer, and many prominent posters. Except you; and pj, and db, and mps, and others. WE NEED YOU!!

You see, this excellent thread is somewhat hidden in the knife review forum; I have nothing against this forum, mind you, and read it regularly, but I think that our information on knife alloys should be centralized. It seems rather fragmented to me as it is now. Bringing all of us together on one thread will improve it immeasurably.

So, come on over (some of you already have), and let the chips fly! Walt
 
Note in regard to the even lower grits (as mps noted) they can as mps noted improve improve performace but not all steels take to them well. For example I took the Buck and gave it a finish with an x-coarse diamond DMT pad and it chipped out the edge badly (relative term). The cheap stainless did not take to this coarse of a grinding at all. However for most slicing work (rope, cardboard etc.) these little chips do not matter, the edge still slices well. On some more "floppy" material it tends to snag a little. It would be interesting to do a test and see how the edge holding vs slicing ability looks as you go from really coarse to really fine.

-Cliff
 
Cliff, the only way that we're gonna get the kind of testing that we want is if _WE_ keep plugging away at testing bit by bit. I wouldn't expect any help from any in the knife or magazine industries. What I would _hope_ is that more and more posters and users would say, "Gee this doesn't look too tough, maybe I'll give it a try and post my unbiased results." As far as I can tell, that's the only way that we're going to achieve anything like a decent snapshot of what is out there.

One thing that I'm personally curious about is which of the mindboggling choice of alloys out there will support a _thin_ coarse aggressive edge? For my uses, that data alone would greatly narrow my choices since for me, that's the kind of edge that I use. Others might wish to approach from the exact opposite end of the criteria.

One thing I need to clarify is that while I'm a great admirer of A2, I was speaking solely of edge formation, not necessarily edge retention. A2 will take a very interesting semi-coarse edge when coaxed. What I'd love to see is a perfect merger of edge formation and edge retention.

mps
 
About the A2, yeah I realized that's what you meant. That is the first time I have ever seen A2 promoted as having anything other than just good toughness.

As for everybody doing some testing that would be excellent. Just imagine the wealth of information that we would have if everyone took just one of their knives and wrote up an evaluation of it. Doesn't this forum have over a 1000 members now? Bladeforums could even create a link page with all the knives reviewed and you would just click on the knife name and get a list of all reviews done on it.

Maybe to promote this Mike could offer a prize for the best knife evalution and hold this "contest" on a semi-regular basis.

-Cliff
 
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