440V's brittleness?

The native has a shorter blade (should wear faster). The native gets thick quicker (should bind more).

One other possible variable, how old is your military? It sounds like Spyderco reduced the hardness on their 440V to 55.5RC recently. An older military may be harder.

 
O_D, I'm talking about the thickness of the blade in general, not the edge.

Much of the 440V discussions focus on the edge thickness (ie sharpening to a really acute angle makes for a high-performing but structurally weak edge).

However, my take on your cardboard test was to point out that the blade (not edge) thickness would be a factor in making the Native perform poorly, because (as Jeff rightly noted) the thicker blade on the Native would probably tend to drag or bind more when pulled thru cardboard than the Military, since the Native's blade reaches its full thickness midway across the width of the blade (about 1/2").

So what I'm saying is that the Native blade (not edge) geometry is thicker which equates to poorer performance (relative to a full flat ground blade, or a narrower width blade) in anything that requires pulling the whole blade thru the material being cut.

Jeff's other good point relative to blade geometry was the longer blade on the Military. Similar amounts of cardboard cut by both knives results in less edge wear for the longer blade because it has more edge to spread the work over.

The moral: don't use the Native on a lot of cardboard boxes (with or without staples
smile.gif
)

OTOH, it should have a heck of a punch in a stabbing motion. I'd imagine the Native would tolerate a punch thru heavy material better than the Military.


[This message has been edited by Longden (edited 14 December 1999).]
 
Hmmmm.... you may have something there with the length of the blade. However, I would think that the width vs. thickness wrt grind (flat vs. hollow) would not cause the cardboard to buckle at the edge. Adding drag, yeah, I understand that, and agree. But, I think it would be purely the thickness and sharpness of the edge that would cause the cardboard to buckle. With that said, I maintain that, subjectively, the Military stayed sharper, longer. Due to longer blade, giving more cutting area? Sure. I can't think of any other reason. Oh, and in answer to the question of the age of the Military... to the best of my knowledge, it is the newest model. I can say for certain that I just bought it. And, to the best of my knowledge, the distributor that I bought it from hadn't had it laying around....

------------------
It's just a ****ing staple!
Maybe we should make knife blades out of staples!
Outlaw_Dogboy, Pax River NAS, Republik of Marilundt


 
The Military also has a distal taper which affects the "feel" and provides less & less drag on a pull stroke through cardbard because the blade is getting thinner as you get closer to the tip.

Also keep in mind that the BF Native was rushed through to make the Blade show and we only made one run eliminating the possiblility for finding glitches and improving or refining.

sal
 
Sal et al, I really don't think there is anything wrong with the, or my, BF Native. It is what it is, and it is a great knife. And, 440V is a great stainless steel. But, I guess what is getting to me is that it is still just that: stainless steel. It will get dull, and in the BF Native the way I used it, it will get dull pretty quickly. 440V in the Military, used the way I use it, and the way I used the BF Native (well, except for staples, so far), seems (subjectively) to hold its edge better. Since my Military supposedly is the same hardness as my BFN, the only thing that I can think of that would make the Native not hold its edge as well as the Mil is the edge geometry, and/or the blade length (since it makes sense that I'm using the smaller portion of the Native more for a given amount of cutting).

I like 440V. I really like my BF Native, and my Military.

I also like ATS-55 (better than the ATS-34, at least in my BM's). I like VG-10. I think I like 440C. I like M2. I'm leaning more and more toward high carbon/lower chromium steels, like M2, 1095, A2, etc., the more and more I use them. They seem to hold an edge just as well (better actually), are tougher, and when they get dull, are easier to sharpen. The only thing they don't have going for them are stain resistance.

I think it's time I'm out of this discussion.

------------------
Absolute safety is for those who don't have the balls to live in the real world.
Outlaw_Dogboy, Pax River NAS, Republik of Marilundt

 
Outlaw :

After all, I don't think any knives are really designed to cut metal.
Click to expand...

The steels used in modern high quality blades should be far stronger and tougher than staples. I have lots of blades that will shear completely though normal staples without doing visible damage to the edge and the edges are not excessively thick. The only blades I have that I would be concerned about this are very use specific blades, fillet knives for example. I am talking about standard staples found in your every day office desk, not staples used in roofing guns that are the thickness of finishing nails.

To be specific I did some cutting today with a Buck "Zipper", steel is 425-mod at a RC of 57. I first put 5 staples down the center of a piece of 1/8" ridged cardboard, put the stapled section alongside a piece of 1x6 and then ran the knife down along side the board and through the staples. I then put five more staples into the cardboard, layed the cardboard on the 1x6" and sliced neatly through the staples.

The results of the first cut was that the staples were cut about 1/3 to 1/2 way through and then ripped out of the cardboard. One section of the blade was used, it was a controlled stroke. The only effect I could see by eye was a small part about 2mm long that was indented. Under magnification I could see that section was deformed not chipped and I could see stress lines running parallel to the edge along that section. The deformation was about .2 to .3 mm deep.

The second cut as noted above neatly sliced through all 5 staples. I used another section of the blade which was not visibly effected by the cut. Under magnification I could see the edge was distorted in the impact area. The edge was rolled to a depth of about .1mm in that area. There was a little sliver of the edge torn off, it was less than a mm in length and about .02 mm in thickness.

To restore the blade I steeled it on a smooth steel 10 times and then gave it 2 light strokes on a ceramic rod (800 grit). The blade was now push shaving sharp and no imperfections could be seen on the edge. The edge on the Buck has an included angle of about 40 degrees and the blade is about .8mm thick behind the bevel.

-Cliff




[This message has been edited by Cliff Stamp (edited 18 December 1999).]
 
Cliff, thanks for the staple report. As a matter of technique I would test office staple cutting with the staples clenching about 10 sheets of 20-wt bond paper. This is a more representative substrate than cardboard for this type of staple and holds the staples securely.

BTW, are you sure your Buck Zipper is made from 425M alloy? They switched from 425M to 420HC in 1994.
 
Um, Cliff, I just have to ask: Have you done that, or will you do that, with some 440V? Say, in a Native?

I have yet to be able to cut through any staple, with any knife. Maybe I just don't press hard enough. But, back to my original incident... it didn't cut through the staple. Sounds like it did just like your first strike... slid across the top, scoring the staple a little. I didn't go back for a second try, since it was an accident to start with.

------------------
Absolute safety is for those who don't have the balls to live in the real world.
Outlaw_Dogboy, Pax River NAS, Republik of Marilundt

 
Jeff, I have done some cutting with the staples more securely bonded but I didn't think the results indicated real world stress as I had to use too controlled a situation. As for the Zipper, yeah, I asked about it on the Buck forums sometime ago and got those specs based on the time of purchase.

Outlaw, I don't have a 440V blade at present, I will do it with a variety of steels though for a variety of situations including tightly bonded staples.

To be clear, it is far worse to rip a staple out than cut through it. If the staple cannot move at all then the blade edge just comes under a compression. Since the blade steel is very hard compared to the staple metal, the staple gets sheared in half and the blade is not significantly effected. However if the staple is not tightly bound then the blade makes an initial cut and as before, fights compression and wins. However there is now a violent twisting action as the staple rips out of the cardboard and snaps hard across the edge.

-Cliff

[This message has been edited by Cliff Stamp (edited 21 December 1999).]
 
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