Strength / durability of Boye's cast materials

C

Cliff Stamp

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The cutting ability of Boye's cast 440C and Cobalt is fairly well known, however what about the resistance of the edge to damage? What is the functional difference in his cast 440C and regular 440C in this area? The cast Cobalt is particularly interesting in this regard as I have seen specs of it at 39 RC. Note as well that Boye likes to grind his blades very thin at the edge, making them great cutters obviously but again I wonder about strength/durability. Does anyone have any experience in this regard?

-Cliff
 
I found the edge to be brittle and prone to chipping. I don`t use my Boyes to cut anything that might encounter anything like a staple or a wire. For things like cardboard or food, the knives are wonderful and will hold an edge forever. (I`ve found it feels as though it gets sharper with use on cardboard!)
 
I did a French knife from one of his cast blanks about 1992. The last time I saw the chef I did it for was two years later and he still raved about the knifes ability to hold an edge. I've been thinking about doing a fighter with similar steel from J. Brown in AZ. I like the stuff and wish I'd done a lot more with it.

Jake
 
When I was at Steve Harvey's, he showed me a Boye Dendritic Cobalt folder which had the edge turned, ever so slightly, when he was doing radial cuts through the bottom of a coke bottle.

At the same time, a Talonite folder I had lost a 1 1/2" strip of its' edge doing the same test. It was flat ground, the Boye was hollow ground.

Both of these failures were probably due to the edge being too thin. I also had a hollow ground Kit Carson Talonite folder with me, and I cut through coke bottles and plastic flower pots without any damage or even dulling of the knife blade. The edge on the Carson folder was slightly thicker, according to Steve (I don't know enough to be able to tell).

Walt
 
I've not had a chipping problem with any of the Boye knives I own, but then I avoid lateral stress moves on all my knives.

In the literature that David sends with his knives he has a photo, famous now?...of him cutting something like 3000 cuts of hemp rope, but after cutting that he states he also chopped through a 6" log, and made cuts into the top of a metal barrel. And the knife needed about a minute of touch up on ceramic to bring it back to hair popping sharp. Tall claim, but the knives I have are very sharp, I've a Basic 3 that LarryLuana traded me a while back, thanks again Larry!, that I sent in to David and ask that he make the edge profile slimmer for cutting leather, which he did and it's a great slicer, good before but now it glides through leather. Normally use box cutters on my leather work, but when I need to cut across a piece that is several thickness I use the Basic 3 and push cut straight through.

The Cobalt, well the one I had would cut the fiberous material great, since David told me that's what it was for, I used that info to limit what I did cut, but it made it necessary to carry another knife for other material, darn have to carry more than one knife....
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G2

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G2 LeatherWorks
 
I really love Boye Dendritic 440C. The stuff is stain resistant, has toughness properties roughly equivalent to ATS-34, and holds an edge very well. To my way of thinking, it is kind of an exotic equivalent of CPM440V in terms of performance. I am sure heat treatment is a big variable, but my Barry Dawson 440C blade goes dull at a steady rate. It is very predictable, make a hundred cuts through cardboard, and the edge will show obvious need of touch up. With BDS, you get tired before the edge goes away, similar to the performance of tool steel edges. Boye claims BDS is more wear resistant than tool steel, but I would say they are closer to even. I think of it as stainless tool steel.

You could conclude from the comparisons to ATS-34 and 440V that it is not excedingly tough, and you would be right. David hollow grinds the edges on his folders nice and thin, and they chip under moderate lateral force. However, on his flat ground customs and basics there is more metal behind the edge, and they are quite strong. The thin edges cut like stink! You really have to try a knife with an edge like this. This kind of cutting performance is what keeps people buying $800 chisel ground Phil Hartsfield blades. They just don't realize it isn't magic. Everyone should know the price they are paying in cutting efficiency for those thick strong edges on those "combat" knives.

In the test that Gary alluded to, David cut about half way around an oil drum with one of his 7" kitchen knives without significant damage. That knife is at the David Boye Gallery, and the edge is just a tad thicker than on his usual kitchen knives, but there is very little chipping in the edge from the oil drum ordeal. It held up very well. BDS is great stuff, probably not as tough as A-2 or L-6, but tough enough for utility hunters and kitchen knives, and very stain resistant too. When I asked David about the toughness of BDS, he said you probably wouldn't want to make a sword out of it, but anything else...why not.

Regarding BDC (cast Stellite), Boye says that casting Stellite makes it tougher, and I think it is on a par with Talonite from what I have seen, but it is still only suitable for moderate use when the edge is thin. Talonite seems to do very well in blade formats with thick edges, and I think BDC would too. There is still the question of impact deformation though if you plan on chopping with it. Boye originally brought out BDC for a dive knife version of the Basic III, and it seems perfect for diving knives, after all, how you gonna chop something underwater? (Answer: very slowly)
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[This message has been edited by Steve Harvey (edited 02-04-2000).]
 
While I love the seemingly eternal cutting action of the dendritic 440C, my folder began to develop very small chips at the base of the blade after sharpening on fine ceramic Crock Sticks. You can barely see them with the naked eye, but they show up real well when viewed with a jeweler's loupe.


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If it's stupid but works, then it isn't stupid!
 
Steve :

my Barry Dawson 440C blade goes dull at a steady rate. It is very predictable, make a hundred cuts through cardboard, and the edge will show obvious need of touch up.
Click to expand...

How long are the cuts, how thick is the cardboard?

Talonite seems to do very well in blade formats with thick edges
Click to expand...

Can you give a rough estimate of how much thicker it needs to be than a good steel?

Walt :

At the same time, a Talonite folder I had lost a 1 1/2" strip of its' edge doing the same test.
Click to expand...

What was the edge bevel angle? How thick was the blade just behind the bevel?

Ron Hood took a Boye Basic with him on one of his trips. Does anyone know if he ever described how it performed?

-Cliff
 
Cliff,

On the cardboard, it's the middleweight stuff, about 3/16 thick. I don't know exactly how they rate it. I will look at the printing tonight and see if I can see some sort of weight. I think Barry shoots for about 58-59 RcH on his edges if I remember right.

I would estimate that the Talonite Kit Carson M-16 had an edge that was pretty close to what one usually see on "tactical" knives. I would guess around .03", give or take a little. What would you estimate, Walt? At that thickness, it seemed quite durable and a good cutter.

In comparison, I would think that on a really well heat treated piece of steel you should be able to take the edge down to almost nothing, and it should still be fairly durable, assuming a flat grind and a fairly robust primary bevel. The edge bevels on my BDS hunter are so small you can hardly see them, and the edge is pretty durable. I should give it the soda bottle test.



[This message has been edited by Steve Harvey (edited 02-07-2000).]
 
Steve, have you ever needed to cut something and not used the BDS hunter because of not wanting to damage it or is it as functinally strong and tough for what you need to do?

Regarding the soda bottle test, is is just making circular cuts around the hard plastic on the bottom or do you do torque the blade when the edge is embedded in the thicker plastic near the center? How close to the center do you make the cuts?

I took a large (2L) coke bottle yesterday and using a VG-10 F1 made radial cuts with no damage to the edge. The blade is about .035" behind the bevel which has an included angle of about 40 degrees. I then cut deep into the center until the blade got stuck and twisted it around. This did deform the edge enough so that light was reflected from it. This was not visible at arms length and I worked it out with a steel (50 strokes).

I repeated this with a Talonite knife from Allen Blade which is a bit thinner behind the edge, .03"m but has a slightly more obtuse included angle, about 44 degrees. It did all the cutting easily but I didn't do the torquing as I want to do a more complete performance evaluation before I have to consider reprofiling out possible chips. The blade was not significantly effected and still push shaved.

-Cliff
 
I've never been inclined to baby that knife, but I don't think of it as particularly tough and try to keep most of the forces applied to the edge in the cutting direction. I wouldn't hesitate to use it for anything that didn't involve cutting really hard materials like hard plastics or metal. I generally consider it as strong as the next knife, but keeping in mind the thinner than average edge. A friend of mine pried open a sliding window with his Boye BDS folder one time and popped a couple of good sized chips out of the edge. They were still clearly visible after a thorough sharpening. In thicker cross-sections, I would say it is pretty much as tough as any high-alloy steel though.

I was making radial cuts when I started seeing deformations in the edge of my BDC folder, intending to cut straight across the bottom of the bottle if possible. The cut ran off at an angle as it neared the really hard area in the center, and the lateral force from that slight turn was enough to deform the edge. The narrowness of the plastic is the danger. Hard cutting on wood that slices off chips a half inch wide or so represents no danger. I wouldn't expect the soda bottle cutting to be a danger to any steel blade unless the blade and/or edge are very thin.

It sounds like your Blade Talonite knife has edge geometry similar to Walt's Carson M-16. I was also unable to damage that knife on hard plastic, though I admit, having already destroyed one of Walt's knives that week, I may not have been putting my whole heart into it
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It did cut well into the very hard middle and jam without any visible damage at all. I think Talonite in that configuration should be strong enough for a cutting tool, if the cutting efficiency is satisfactory to the owner. BDC should be equally durable with a strong edge shape. A person could get a BDC Boye Basic III dive knife as a pretty low cost tester. Chai cutlery lists them for $142. I am really fond of my BDS Basic III with a cord wrap handle.
 
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