Chisel Grind...Why?

Discussion in 'General Knife Discussion' started by d762nato, Jan 6, 2016.

  1. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    One is a general physician and the other is a plastic surgeon.
     
  2. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    There are certain blades for microtomy work for things like eye surgery that have highly specialized shapes (like slicing off the lens of the eye) that are chisel-ground with a rounded point and double edge, but that's for a very specific cut where it makes good sense.
     
  3. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    If you're able to actually get your hands on a chisel-ground scalpel, please snap a photo. I'd also be interested in the blade number and manufacturer.
     
  4. EChoil

    EChoil Banned BANNED

    May 22, 2014
    Whoa.....that's almost like saying there are NONE out there.

    I'm still under the impression that millions of disposable, sani-wrapped, inexpensive but reliable, one--time use, basically chisel-ground "scalpels" exist out there for general use. As I said it's hard to find firm documentation on true numbers in the short time I had to research it.

    It also could be that technology has finally allowed a shift in that industry recently to a V-grind "standard" that I just haven't caught up on yet. Admittedly I am recalling experience from several years ago, most of it offhand, as I was never one interested in carrying scalpels.
     
  5. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    To the best of my knowledge scalpels have always been double beveled. I've seen plenty of vintage reusable ones over time and they were all double beveled.

    All of the plastic handled disposables I've seen have also been double-beveled.

    The only reason why chisel grinds would be less expensive to produce would be in the tooling expense for grinders and fixtures, because the same amount of metal has to be removed whether you're doing a double beveled grind or a chisel grind. Because scalpel manufacturers are already making double-beveled blades, there's no extra expense for them to produce their disposable scalpels with double bevels.
     
  6. EChoil

    EChoil Banned BANNED

    May 22, 2014
    We're in two "to the best of my knowledge" whirlpools here.

    I wish a manufacturer/craftsman with bona fides in that medical commercial industry could show up.....

    I used a lot of disposable scalpels for utility and projects here and there over a number of years and as i recall they were chisel ground....and apparently cheap. LANCETS, of course, have probably always been V-ground.

    Of course, I'm still sitting here in firm belief that basically when you chisel grind a given blank it makes the edge about twice as sharp as the double-grind since it essentially cuts the edge angle in half.

    Geometry again. :)
     
  7. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    Again, a chisel grind is not the same as halving a double bevel grind. That would be halving your edge angle, which is going to have higher cutting performance, but you can achieve the exact same result by halving the edge angle of a double bevel grind...
     
  8. EChoil

    EChoil Banned BANNED

    May 22, 2014
    Obvious. A chisel grind is not the same thing as halving a double bevel grind.

    Yes, it is halving the edge angle which gives a higher level of cutting performance.

    I think a chisel profile is going to be sharper, i.e. a better cutter as you say above, even after halving the edge angle of a double bevel grind.

    Edge strength---a different story.
     
  9. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    Sharpness is the diameter of the apex, not the geometry behind that apex--sharpness and blade geometry combine to give you cutting performance. A chisel profile will not be a better cutter than a double bevel grind of equal included edge angle. Can you find a single scientifically valid assertion for that? What would the mechanism be that would produce this higher cutting performance?
     
  10. Lycosa

    Lycosa

    Aug 24, 2007
    The ball goes back and forth. What a match.
     
  11. EChoil

    EChoil Banned BANNED

    May 22, 2014
    Can you?

    I thought that was the whole conundrum here....we can't find anyone with bona fides.

    Scientific?? Well, one of my many virtual mentors on edges is Prof. Roland Phlip, the ballisong guy. He's probably a PhD. Is that scientific?

    Your turn. Whose your "scientist" ? Throw some of your stuff down now.
     
  12. ocnLogan

    ocnLogan

    Jul 31, 2011
    Strangely, this is exactly what I thought people were having issues understanding before. The included edge angle being the same means... they are the same. The chisel grind has a 30 degree on one side, and a zero ground other side, while the double bevel has 15 degrees on each side. The "triangle" we're talking about has just been rotated with a chisel grind.

    This is another thing I see frequently misunderstood, and you did a great job explaining it. This is also why you can get a good sharp edge that isn't polished, as the "sharpness" is all about the width/alignment of the apex. And this is also why so many knives can have such different geometries, but can all still cut paper well, or shave (because both of those medias are quite thin, which basically ignores the rest of the geometry). But by the same token, this is why a thick "sharp" knife (like my BK2) can struggle to cut long lengths of thick double layer cardboard, while a "dull" thin knife like an opinel can do the same job much better, as the geometry behind the edge is designed for totally different things.

    Also, I applaud you both (EChoil and FourtyTwoBlades) for remaining civil about this. That's not an easy thing for most to do on the internet. So I award both of you two totally arbitrary and important, but simultaneously completely valueless "internet points". Feel free to brag about them to your friends, as long as you don't try to redeem them for a cash value, you should be happy :p.

    :thumbup:
     
  13. EChoil

    EChoil Banned BANNED

    May 22, 2014
    *LOL* Not a "match" by any means. I'm just trying to get to the facts. All he or I can do is speak from experience--it varies a bit. I'm just here to learn. I said before...I hope someone proves me wrong so I'll know for sure.

    Gettin' some views though, huh? I can't imagine anyone wading through all 9 pages of this. I wonder if d762nato realizes what he started.

    btw, I got that the other day. I haven't figured out how to work it yet to get back with you on it. Sorry.
     
  14. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    I've thoroughly explained my reasoning using scientific concepts, and you're making an attempt to shift burden of proof, as well as a combined appeal to authority/genetic fallacy.

    However, a lot of the physical dynamics of edged tools I've learned either from engineering resources or from folks like the infamous Cliff Stamp, who, despite my subtle disagreement with some of his conclusions and finding his attitude commonly abrasive, is a physics professor and has devoted a tremendous amount of time and painstaking effort into the scientific research of the performance of cutting implements.
     
  15. EChoil

    EChoil Banned BANNED

    May 22, 2014
    Thanks, but maybe I should be real clear here so nothing rears its ugly head....

    I stated earlier---FortyTwo knows his stuff inside and out. As well as anyone on this forum. I try to read everything he writes and always will. He knows more about the technicalities of edges and blades than I do. He's helping me catch up though.

    I'm just seeking clarity. :) He's already cleared up a lot of things for me. I'm only throwing some of my own experiences and thoughts out here from time to time during all this. I'll never possess his technical knowledge.
     
  16. EChoil

    EChoil Banned BANNED

    May 22, 2014
    So uh..... :cool:

    You think this thread'll become the STICKY for chisel grind....? :D
     
  17. chuxwan

    chuxwan

    423
    Aug 26, 2012
    Echoil, it really seems like you are choosing to be led on by the terms themselves rather than accept the basic geometry. There is nothing inherent in a chisel ground blade that must mean it is ground to half the edge angle of a v ground blade. We are comparing the edges given the same theoretical angle because it is the only way to compare them. And while the idea of scalpel blades being v or chisel ground is an interesting discussion, it is conjecture to cling to the notion that chisel ground blades are for some reason sharper, given that there is no geometric possibility. The misstatement from the doctors perspective is an error of language which could happen any number of ways (i.e. between two different models of scalpel available, the chisel ground was sharper or more effective) which do not attempt to address more than the situation at hand, let alone make a sweeping generality about the inherent properties of edge geometry.
     
    Last edited: Jan 9, 2016
  18. EChoil

    EChoil Banned BANNED

    May 22, 2014
    I realize that. And did I say there is "...something inherent in a chisel ground blade that must mean it is ground to half the edge angle of a v ground blade" ? I don't think I did.

    "Sharper"? OK, how about "cutter"? In my experience chisel grind can be better cutters. "Sharper," "cutter,".... whatever.

    What was a doctor's misstatement? Huh?

    Dude....all I said was I think most of the common disposable scalpels out there are chisel ground--as in worldwide, scalpels as a whole. I still think that--the basic everyday, inexpensive, disposable scalpel. What, am I having to repeat now?

    Didn't you see that the whole thing in regard to that little piece of this thread is that we can't find good documentation either way? If I'm wrong, I'm wrong. But at this point I'd like to know for sure, that's all. Someone with bona fides comes along to answer the question definitively, fine. If not, what're we gonna do, harp on THAT all day? :) At best it would be a minor little factoid...for whose use I haven't a clue. It's just something that came up.
     
  19. trevitrace

    trevitrace Gold Member Gold Member

    Jul 21, 2013
    Boris?
     
  20. FortyTwoBlades

    FortyTwoBlades Baryonyx walkeri Dealer / Materials Provider

    Mar 8, 2008
    If you do some quick google image searches for disposable scalpels, while you don't see both sides of each individual scalpel, you'll find countless images showing different models facing both left and right, and a bevel is always clearly visible in each instance. Between this, the 360° image I found and linked earlier, and the opinions of two knife nut doctors who have claimed never to have seen a chisel-ground scalpel, there's a bevy of circumstantial evidence to suggest that they are not commonplace.
     

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