INFI & Thin Edge Geometry

[Vivi]

Spyderco ships many of their knives straight from the factory with a 15 degree inclusive edge (7.5 degrees per side), like the Byrd Cara Cara CE I recently acquired. More often than hearing complaints about how weak the edges are, you hear users commenting on how effective these edges are at cutting.

Debating edge geometries is fun and all, but would prefer this topic to get back to what it begun as. PM me if you wish.

how hard are the steels you're taking to such acute angles? Infi is made to be tough, not super hard. A certain degree of malleableness comes with the territory, malleable and super thin spells rolls and dents in my book.

I'm not sure but I think between 57 and 60RC. My most commonly use steels are VG10, S30V, CPMD2 and SR101. I don't know what RC Swamprat and Scrapyard use on SR101 but it's one of my favorite steels. I wish more knives were made in it. It's treated me good so far at 10 degrees per side, plan on taking it thinner when I find the time.

I have never cut with INFI, and most of what I've read has been about it's toughness. I haven't found much information on how smaller INFI blades work with 10 degree per side edges, or thinner. Surely someone here has tried it.

 

[Last Visible Canary]

http://www.bladeforums.com/forums/showthread.php?t=258583&highlight=jerry+thin

Jerry:
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"In extremely thin edges, such as are planned for the Hunter/Utility line, D-2 will prove to be a superior choice. The same qualities that make SR-101 a great steel for abuse, play against the house when it comes to extremely thin cross sections. Under contact (cutting not chopping) with harder materials such as metal banding, bone, rock, etc. . . SR-101 will roll whereas D-2 will prove to be the clear winner in these applications. However, if you do any heavy lateral stressing on a thin cross sectioned D-2 blade, you may be glad that your Swamp Rat D-2 blade is backed by the best no BS warranty in the industry!

-----

So, in summary, for an uncoated blade with extremely thin cross sections, where cutting is the only intended application and hard materials such as bone, metal banding, etc…will be in contact with the edge, D-2 will prove to be a superior steel in edge holding and resistance to the elements.

In more abusive applications where cutting is to be coupled with prying, lateral stressing, high impact, and overall toughness, SR-101 will prove to be far superior to D-2.” --- Jerry Busse

sr101 is not far off from infi in use, and the comparisons made between sr101 and d2 can be applied directly to infi. It is not made for thin cross sections, if you apply lateral forces to the edge (at less then 10 degree's per side) it will roll, mash and dent. it may be 58rc, but it's quite maleable when it's thin.

I can't comment on how an infi edge wears if the person "

uses their knives properly,

" in that geometry, cause I don't think I've ever used a knife properly.

 

[Bigfattyt]

If I was going to go that thin on an edc sized knife from Busse in INFI, I would look around for a BAD. They are a thin higher hardness AD knife. They are 62 rc if I remember correctly.

That would likely give you the best success for the type of edge you are looking for.

I must be hard on my edges. I took some of my edges down to 20 per side (on a Lansky system, so you clamp and go, but that does not really mean you are at the stated angle, due to differences in spine to edge blade height). I went back to 25 per side on most of my users back then.

Now I convex my user edges, so I am not really sure what angle, but I can for sure say that none of my Infi is less than 20 per side.

I really need to try some sr101 from swamp rat, so I can get a feel for it. I think in an edc sized blade, it should be great.

If you really are just using it for light cutting, It might hold up, but at that angle, any lateral stress, and I predict rolling rippling of the edge.

 

[Vivi]

http://www.bladeforums.com/forums/showthread.php?t=258583&highlight=jerry+thin

sr101 is not far off from infi in use, and the comparisons made between sr101 and d2 can be applied directly to infi. It is not made for thin cross sections, if you apply lateral forces to the edge (at less then 10 degree's per side) it will roll, mash and dent. it may be 58rc, but it's quite maleable when it's thin.

I can't comment on how an infi edge wears if the person "" in that geometry, cause I don't think I've ever used a knife properly.

Thanks for the link & info (also thanks to bigfattyt). I had remembered reading about a certain knife they ran to a higher RC and with a thinner edge, couldn't remember which one though. I'll keep an eye out for a BAD, aside from the choil looks great. The handle looks comfortable.

@BigfattyT: How thin an edge one should use has a lot to do with what you're cutting. Maybe you just cut different things than I do. I'm also careful with my knives, like no cutting on ceramic plates or steel countertops, no swinging my choppers into rocks, no cutting metal with my really thin knives etc. Most of the things I cut aren't very hard on a knife edge. The hardest things I usually cut are thick plastics or knotty hardwood, both of which I've found can be cut with knives thinner than 10 degrees per side.

 

[Bigfattyt]

Thanks for the link. I had remembered reading about a certain knife they ran to a higher RC and with a thinner edge, couldn't remember which one though. I'll keep an eye out for a BAD, aside from the choil looks great. The handle looks comfortable.

agreed about the choil on a knife that length. It either needs to be a micro choil, or no choil on a knife that size. Although, really, I don't notice the choil on my GW to much. But every once in a while, I catch some soft material in their (some one mentioned cutting bunched plastic, like bags.......that is funny because that is one of the times it annoys me, that and cutting cloth sacs like burlap etc).


With thinner edges, I have found I have to sharpen them too often, and they are not durable enough for me. Although, I have to say, I use a strop now, and it is so much easier to do a few quick passes than my old Lansky ever would be.

I had a BAD, which I loved, but I was not in love with the handle color, so I traded it for a fat thick Ash1CG.

I would love another in a different color, as I never really tested it out.

 

[Jack Shen]

12.5 per side is the lowest, I'd be willing to take a EDC knife down to, that's kind of my rule of thumb for any type of steel. And that would be for normal cutting... ie. rope, cardboard, whittling wood, that type stuff. Anything will roll and/or chip if you try to cut something hard like a metal band, and definitely no prying with the tip. Busse stuff should bend, the rest may snap off.

A buddy of mine asked me to sharpen his benchmade (think it was s30v or 154cm ) . I figured he just be cutting packages and maybe carpet here and there, so I did it at 12.5 degrees per side. He was coming back like every few weeks needing a major resharpening. He has chips, rolls, the works. So finally I asked him what he'd been cutting.... wires,metal bands, apparently a lot of things that contained metal. So I re did it at 20 degrees per side.... No more problems

 

[t1mpani]

SR-101 is 52100 with a differential heat treat.

As to super thin edges on INFI, I haven't found that its edge stability at less than 20 degrees included is particularly exemplary, although it does show its usual amazing ability (for a nearly stainless steel at 60 HRC) to deform without fracturing, and I don't think I've ever had a roll at this geometry that didn't pull out easily enough on a butcher's steel. Edge durability at very thin geometries when it comes to dulling through abrasion and blunting is the one area I'd say that 3V pulls ahead of INFI, although it falls behind again in almost every other comparison, and I say that as a 3V fan. I bring it up simply because this is a steel that many often compare INFI to. Less ductile steels will always do better with very thin edges in terms of rolling and blunting. Of course, when something does go wrong, you pay for it with greater likelihood of chipping/fracture.

For awhile, my AD was profiled to exacto-knife levels and it did okay, but it's much happier at the 25 degrees (approximately) it sits at now. Absolutely everything is a trade-off. Anyone who says differently wants your money or your vote.

 

[cotdt]

INFI is heat treated for toughness. Thin edges are mainly a function of strength (hardness), basically if you want less than 10 degrees per side without taking dents easily you want at least 61 rc. INFI can obtain 61 rc but it's not heat treated this way. If it was, it would be both very strong and still quite tough, very desirable for thin edges.

Actually this is kind of ironic, because if you want to formulate a steel that is great for holding thin edges, its composition would look similar to INFI.

 

[mhawg]

Thanks for the contribution to my thread.

I've made numerous videos and written articles of such reprofiled knives carving wood, cutting various cables and wires, cutting plastic water canisters, cutting food, slicing beer cans, slicing paper, batoning wood, chopping wood, cutting rope and so on to show others that yes thin knives can be used without them falling into pieces by looking at them wrong.

Would like to know how INFI works with such geometries because it is what I use for my knives and it works for me.

I've been chopping wood for over 40 years and I have found that the thin edge cuts great early but if you are out in the woods and can only sharpen once in the morning it is better to have a broader angle to sustain a working edge all day. Thin probably works good when you are in the back yard and can hit a stone fairly often.

 

[steelnut]

I have a High St, and will bring it to Resinguy's winter lunch if you are going?:thumbup:

 

[resinguy]

I can bring a BAD and a Banned AD the the lunch, and a Vex.

What Vivi is talking about, the thin edges, is not new or surprising. Cliff Stamp was a strong proponent of the concept here on BF and his own site; and before that it was amply explained on the old rec:knives message boards. Indeed, Cliff said that the whole point of expensive modern steels was to allow the user to take advantage of their better properties and use more acute angles to gain superior cutting performance. You can head over to the Maintenance forum and find some other thoughtful users who take their edges down to acute angles.

So when someone comes along and asks if a small EDC Busse knife can be used (with reasonable precautions) at 10 degrees per side or less, because he knows that he can use his Spydercos at that angle, just answer the question based on your own actual experience, but please don't reply as though the very idea is ridiculous.

 

[mhawg]

OK, I can see it on a small blade designed for slicing and no contact with bone. I feel like you lose the other end of the usability scale when you take the edge down that far though.

 

[230grains]

I can bring a BAD and a Banned AD the the lunch, and a Vex.

What Vivi is talking about, the thin edges, is not new or surprising. Cliff Stamp was a strong proponent of the concept here on BF and his own site; and before that it was amply explained on the old rec:knives message boards. Indeed, Cliff said that the whole point of expensive modern steels was to allow the user to take advantage of their better properties and use more acute angles to gain superior cutting performance. You can head over to the Maintenance forum and find some other thoughtful users who take their edges down to acute angles.

So when someone comes along and asks if a small EDC Busse knife can be used (with reasonable precautions) at 10 degrees per side or less, because he knows that he can use his Spydercos at that angle, just answer the question based on your own actual experience, but please don't reply as though the very idea is ridiculous.

The idea is far from ridiculous, but it's all about application. My sarsquatch had NO problems cutting things in an average day. It sliced food excellent, cardboard, zip ties. It even chopped wood AMAZING for a blade it's size. I had thinned the edge down to 10 degrees per side, it was the sharpest knife i've ever owned by far. I could not touch the edge without bleeding. I had no problems with the edge at that geometry until I went and chopped frozen solid wood with it. The knife bit in and when I would pull it up I would put it under some lateral stress. The edge ended up tearing and denting pretty badly. Had I not pounded the edge into the frozen wood, the knife would have continued to hold up perfectly. i don't know if it had anything to do with the blade being frozen as well while using, as I don't know how INFI reacts to extreme cold in such angles, but the knife had frozen water all over it.

For an EDC type blade, I don't think it would be a problem on INFI anymore than it would be on a steel with similar hardness. It's worth a shot, but i'd go thinner progressively, not all at once. One thing I learned through machining is you can always remove more stock, but you can't put it back on.

 

[Jason B.]

Vivi, go with what you know, its just steel


Shoot me a PM or email if you would like to talk about thin edges.

 

[Vivi]

I have a High St, and will bring it to Resinguy's winter lunch if you are going?:thumbup:

I plan to attend, that would be awesome if you could do that.

Resinguy, just a BAD and Vex would be OK, I feel bad as it is asking you to haul around steel for me. At least it's not FFBM's I'm currently after (Eventually though...)

 

[PeterPHWS]

I can bring a BAD and a Banned AD the the lunch, and a Vex.

What Vivi is talking about, the thin edges, is not new or surprising. Cliff Stamp was a strong proponent of the concept here on BF and his own site; and before that it was amply explained on the old rec:knives message boards. Indeed, Cliff said that the whole point of expensive modern steels was to allow the user to take advantage of their better properties and use more acute angles to gain superior cutting performance. You can head over to the Maintenance forum and find some other thoughtful users who take their edges down to acute angles.

So when someone comes along and asks if a small EDC Busse knife can be used (with reasonable precautions) at 10 degrees per side or less, because he knows that he can use his Spydercos at that angle, just answer the question based on your own actual experience, but please don't reply as though the very idea is ridiculous.

Well here is Jerry's take on Noz2002's query about taking Infi to a thin edge .....

Vassili,

Your edge is NOT 30 degrees!. . .

Using YOUR measurements, Your edge angle is 14.45 degrees!!!. . . . And that's pretty darn close to paper thin. . . .

All Busse blades are hand sharpened and are usually held in the 20 - 25 degree angle range.

If you had not put Cobalt on your ignore list you would have seen where he made very similar calculations to our own in the General forum and this could've been finished before it got started. . .


30 degrees is pretty robust and we wouldn't put that on a small knife unless we were really hammered at the time. . . (Always a possibility when dealing with Busse Combat )

I hope this helps,

Jerry

Now if Jerry mentions 14.45 degrees as pretty close to "paper thin" .... and your friend Vivi is talking about 10 degrees and less going as far as 5 degrees .... is it not suprising that some of us who have reasonable experience of using knives and are aware of the problems associated with thin blades rolling ...rippling and even tearing the metal on the edge ...( any metal really at this thinness ).... are not going to advocate doing this ?

Where are the advantages of going this thin?

Given the expense of a good small bladed Infi Busse ... I would have thought it much more prudent to offer cautionary advice .... but would agree there is no need to go as far as saying it is "ridiculous" .... I don't think anyone has said that ... but if you want to claim a recommendation by Cliff Stamp beats cautionary advice by Jerry Busse ... then obviously you are entitled to do so ... it's not ridiculous to endorse going this thin on blades but it might not be a "recipe for success" either .... hence Jerry's remarks on where "paper thin" starts to be an issue ....

Not being funny here ... just trying to make it clear why I myself was sceptical about what was being proposed ...:thumbup:

 

[resinguy]

No, I see your point. I remembered the Nozh affair, but didn't take the time to dig up the details. And I would not suggest that Cliff's general recommendations trump Jerry's advice. It just seemed to me that while Vivi was asking people for their actual experience in taking INFI to narrow angles, most of the answers instead simply dumped on the idea. It would seem that Vivi will have to get a small Busse and try it for himself. Someone mentioned that you can't put metal back, but if the edge is too narrow and it rolls or something, one can just resharpen at a steeper angle and try again.

 

[Lycosa]

For the ultimate edge, isn't the convex edge the best? You can have thick bar-stock on the knife and bring that convex edge right down to a strong, razor sharp edge.

 

[t1mpani]

I like convex edges but they're either thick or thin like any other edge. They have a tendency to outperform flat grinds of equivalent geometry in chopping as they do a better job of splitting materials and not getting wedged, but there's nothing magical about them. If they're thin, they slice well but give up some strength, if they're thick, they're strong but give up some cutting ability.

 

[richard j]

a convex edge to me is the best edge to have on a knife but you can go too thin. i was sent a battle mistress last year that had a convexed edge thinned way down which caused the edge to roll. i had to reconvex the edge so it was a little thicker which luckily didnt take much life from the blade.

a small knife can benefit from a thin edge but a large chopper like a bm will roll if the edge is too thin and the steel cant handle it. i dont see why anyone would thin the edge of a knife down knowing full well the steel cant handle it. each time you remove the damaged area you take life from the blade.