-
The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details: https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is$300$250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
Edge aggression on a slice as influenced by finish and angle
- Thread starter Cliff Stamp
- Start date
- Joined
- Oct 17, 1998
- Messages
- 1,008
You can find the Rosseli knife at www.kellamknives.com. Go to the catalog>knives>fixedblades>R-line.
JD
JD
Once again, this kind of a discussion really depends upon what the knife is used for.
I have a CS Recon Scout that is used for general camping, twisting, prying (YES, prying) and wood chopping. The thick edge from the factory makes it very strong for this kind of use and abuse, and by polishing it up to a very fine finish, I can chop wood for a long time, and restore the edge with a light steeling.
I leave the finer cutting for knives more appropriate to that task.
So I like to have the exact opposite edge - thick and polished - for these kinds of tasks. It works very well. I also have other (read thinner) knives for the finer cutting.
I have a CS Recon Scout that is used for general camping, twisting, prying (YES, prying) and wood chopping. The thick edge from the factory makes it very strong for this kind of use and abuse, and by polishing it up to a very fine finish, I can chop wood for a long time, and restore the edge with a light steeling.
I leave the finer cutting for knives more appropriate to that task.
So I like to have the exact opposite edge - thick and polished - for these kinds of tasks. It works very well. I also have other (read thinner) knives for the finer cutting.
Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
medusaoblongata :
To increase the performance still further, you can grind at a more shallow angle freehand, cutting away most of the shoulder of the edge, just leave the last mm or so left unground. No great amount of skill or consistency is required, you are just hogging away metal. When finished you use the Lansky to sharpen the narrow strip that was left along the very edge.
OwenM :
Thanks for the details Owen, to clarify some of the statments made in the above, there is no argument being put forth that S30V is of low performance, as currently used by Reeve and company. There is also no argument that S30V isn't in the same league as ATS-34 for example, nor even that the RC used by those makers may give the optimal performance characteristics that they desire in a knife. However, a reduction is hardness does product a direct loss in several apsects of knife performance, thus there are drawbacks to using S30V over the steels is it replacing like BG-42 in the Sebenza when they are run several RC points harder.
Jerry Hossom :
Of course RC is not an all inclusive measurement, that is why there are other material properties specified for steels (and other materials). However, some performance attributes are indeed directly correlated to hardness. Impaction resistance for example, as that is what hardness measures. Thus a hard edge will impact less than a softer one (assuming the impact toughness isn't exceeded). Hardness is also very strongly correlated to tensile strength, therefore softer, and thus weaker, edges roll easier than harder ones.
There are effects on grain refinement that can produce changes in tensile strength, see Nu-Bit's articles for example. However I have never seen evidence presented (or even argued) that this change is larger than what would be induced by even a couple of RC points. It is the same for ductility and impact toughness for the most part, assuming a quality heat treatment for which ever cycle was used of course. Specific to cryo, Nu-Bit studied this extensively and found no significant gains in impact toughness, and since they sell the equipment it would be in their advantage to promote it if at all possible.
What is mainly effected by heat treating that is not strongly dependent on hardness are properties like wear and corrosion resistance, as they are controlled by aspects like the carbide structure and segregation (impurity clumping at grain boundries etc.) which don't induce large changes in the RC, even in the same steel, let alone from one to the other. However for most knife use, wear resistance isn't a major factor, as most materials normally cut can't wear steel significantly and the edge blunts by impaction and rolling. Both of those are deformation issues and thus highly correlated to RC as noted in the above. Evidence of this can be seen under magnification, or just by use of a smooth steel on the blunted edge.
As an example or some of the points raised, see Bryson's text where he describes the difference in tempering D2 960F to get 58 RC and grain refinement and increased wear resistance, as compared to 400F to get 62 RC. However he also states that the higher RC is indeed preferred in some applications to prevent deformation. Since how knife edges blunt is *strongly* deformation dependent, hardness is a critical factor, even swamping out huge changes in wear resistance due to alloy content and heat treatment. References to testing on this issue by makers and users is given in the above.
matthew rapaport :
In general, the more hype, the more secrets, as you can't hype something when its performance can be related to something known, and you can't hype at maximal levels if you are specific in your claims as this locks you down, and you don't have the freedom to promote over anything new. There are exceptions though, Busse for example doesn't make a lot of public statements about what they do with their steel, or even the composition. However there is no hype as they guarantee in writing all their claims.
swede79 :
Essentially yes, you take the edge down to the profile at which it has the necessary level of durability. That being said, since the edge profiles on "tactical" knives are usually 50+ in excess of what is found on a felling axe, they are vastly overbuilt unless you are cutting heavy bone, or metal. And even in those cases, you don't need the entire edge at the obtuse angles used, just the last mm or so. And you really don't need them nearly as thick as it common, getting specific 0.040" is very difficult to ripple even on a large knife using loose technique with excessive force on hard small diameter dead wood. Going thicker still would only be necessary if you wanted to resist heavy metal edge impacts across the edge.
-Cliff
To increase the performance still further, you can grind at a more shallow angle freehand, cutting away most of the shoulder of the edge, just leave the last mm or so left unground. No great amount of skill or consistency is required, you are just hogging away metal. When finished you use the Lansky to sharpen the narrow strip that was left along the very edge.
OwenM :
Thanks for the details Owen, to clarify some of the statments made in the above, there is no argument being put forth that S30V is of low performance, as currently used by Reeve and company. There is also no argument that S30V isn't in the same league as ATS-34 for example, nor even that the RC used by those makers may give the optimal performance characteristics that they desire in a knife. However, a reduction is hardness does product a direct loss in several apsects of knife performance, thus there are drawbacks to using S30V over the steels is it replacing like BG-42 in the Sebenza when they are run several RC points harder.
Jerry Hossom :
Of course RC is not an all inclusive measurement, that is why there are other material properties specified for steels (and other materials). However, some performance attributes are indeed directly correlated to hardness. Impaction resistance for example, as that is what hardness measures. Thus a hard edge will impact less than a softer one (assuming the impact toughness isn't exceeded). Hardness is also very strongly correlated to tensile strength, therefore softer, and thus weaker, edges roll easier than harder ones.
There are effects on grain refinement that can produce changes in tensile strength, see Nu-Bit's articles for example. However I have never seen evidence presented (or even argued) that this change is larger than what would be induced by even a couple of RC points. It is the same for ductility and impact toughness for the most part, assuming a quality heat treatment for which ever cycle was used of course. Specific to cryo, Nu-Bit studied this extensively and found no significant gains in impact toughness, and since they sell the equipment it would be in their advantage to promote it if at all possible.
What is mainly effected by heat treating that is not strongly dependent on hardness are properties like wear and corrosion resistance, as they are controlled by aspects like the carbide structure and segregation (impurity clumping at grain boundries etc.) which don't induce large changes in the RC, even in the same steel, let alone from one to the other. However for most knife use, wear resistance isn't a major factor, as most materials normally cut can't wear steel significantly and the edge blunts by impaction and rolling. Both of those are deformation issues and thus highly correlated to RC as noted in the above. Evidence of this can be seen under magnification, or just by use of a smooth steel on the blunted edge.
As an example or some of the points raised, see Bryson's text where he describes the difference in tempering D2 960F to get 58 RC and grain refinement and increased wear resistance, as compared to 400F to get 62 RC. However he also states that the higher RC is indeed preferred in some applications to prevent deformation. Since how knife edges blunt is *strongly* deformation dependent, hardness is a critical factor, even swamping out huge changes in wear resistance due to alloy content and heat treatment. References to testing on this issue by makers and users is given in the above.
matthew rapaport :
In general, the more hype, the more secrets, as you can't hype something when its performance can be related to something known, and you can't hype at maximal levels if you are specific in your claims as this locks you down, and you don't have the freedom to promote over anything new. There are exceptions though, Busse for example doesn't make a lot of public statements about what they do with their steel, or even the composition. However there is no hype as they guarantee in writing all their claims.
swede79 :
Essentially yes, you take the edge down to the profile at which it has the necessary level of durability. That being said, since the edge profiles on "tactical" knives are usually 50+ in excess of what is found on a felling axe, they are vastly overbuilt unless you are cutting heavy bone, or metal. And even in those cases, you don't need the entire edge at the obtuse angles used, just the last mm or so. And you really don't need them nearly as thick as it common, getting specific 0.040" is very difficult to ripple even on a large knife using loose technique with excessive force on hard small diameter dead wood. Going thicker still would only be necessary if you wanted to resist heavy metal edge impacts across the edge.
-Cliff
If that works for you great. I agree that for a chopper (which is a high force pushcut) a polished edge is optimal. However, for me, a thick edge is a huge disadvantage, by reducing the cross section you increase penetration, and therefore performance in chopping.
As to prying, I take care not to place lateral loads across the edge of the blade, if I need to pry I concrentrate the force (through pressure and placement) high up onto the spine and primary grind where there is more metal to absorb the stresses.
If I need more strength, I try to get it from using high grade materials, advanced heat treat and by designs that reduce stress risers.
The Carbon V you are using is a very impact resistant steel, as well as being quite strong. I think you'll be suprised how thin you can take the edge and still be very durable. I have a Trailmaster that I am running at an included angle of under 25 degrees with a convex edge (the knife was substantially reground by a custom maker and a micarta grip and new guard were put on) and it has never shown any signs of failure. The performance increase over a NIB edge in chopping fresh wood is in the 300% range.
The most optimal chopping tools, such as felling axes, have incredibly thin edges, I'm sure Cliff can provide more details here.
You are right when you write that it is a matter of preference, I happen to like the increased performance that comes from a crisp, highly aligned, thin edge. For pure performance on the types of materials I work with, nothing else comes close. The edge finish is secondary to geometery for me. A thin, very course edge will still shave and push cut well, yet still slice like a demon. A thin, highly polished edge pushcuts like crazy.
For me, thin is in, both in stock thickness and edge geometery. Acute profiles rule. . . .
Chad
Thanks Swede,
Another thing you may want to try is thin out the edge, then add a slightly more obtuse microbevel for added strength, or convex the edge, as the sharpening technique described above will do, just progress to finer abbrasives for a high polish.
I think you'll enjoy the performance improvements from the thinner edge, and you may be suprised at how tough that Carbon V is.
Chad
Another thing you may want to try is thin out the edge, then add a slightly more obtuse microbevel for added strength, or convex the edge, as the sharpening technique described above will do, just progress to finer abbrasives for a high polish.
I think you'll enjoy the performance improvements from the thinner edge, and you may be suprised at how tough that Carbon V is.
Chad
Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Though common perception seems to be that axe edges are thick and obtuse, this is only true for "utility" axes which are found in hardware stores, these are not the same as wood working axes. It would be like expecting a Sebenza to cut the same as a $1.99 import as both of them are folders.
A dedicated felling axe (3 foot handle, 3-5 lbs head) will have an edge profile of around 15 degrees included for fresh wood, and about 25 degrees included for dead wood. Some variance is to be expected for wood type, but even for the worse, the angle is no where near the "tactical" 22 degrees per side which is common for knives.
I currently run my axes at between 20-25 degrees included because the wood around here is very knotty, and I don't currently use a double bitted axe. If I was (which I will be shortly) I would drop the profile down to 15 degrees included on one side and 25 on the other.
I would agree, that is a very lovely knife, Cold Steel should release a pure wood craft version.
-Cliff
A dedicated felling axe (3 foot handle, 3-5 lbs head) will have an edge profile of around 15 degrees included for fresh wood, and about 25 degrees included for dead wood. Some variance is to be expected for wood type, but even for the worse, the angle is no where near the "tactical" 22 degrees per side which is common for knives.
I currently run my axes at between 20-25 degrees included because the wood around here is very knotty, and I don't currently use a double bitted axe. If I was (which I will be shortly) I would drop the profile down to 15 degrees included on one side and 25 on the other.
I would agree, that is a very lovely knife, Cold Steel should release a pure wood craft version.
-Cliff
- Joined
- Jun 21, 2002
- Messages
- 124
I am surprised that this thread has not received more attention since it addresses a basic sharpening philosophy which is somewhat in contrast to what seems to be the norm here, i.e. highly polished edges. Perhaps too many folks are intrigued to the Stamp bashing goin on elsewhere .... Count me out on that.
Gettng back, I understood that the basic premise of this thread was that more acute edges coupled with a coarser grind gives a better general purpose edge. Perhaps I am oversimplifying but that was the impression I got.
I tried this on a Spyderco Native in 440V, using a coarse (Blue) DMT stone mounted in my Edge Pro set at 15 Degrees. A couple of comments about that. One: I am a fan of diamond stones and by changing the length of the knob spacer to about 2 7/8", the Edge Pro holds the DMT 4" stones quite nicely. They cut faster and don't dish. Two: the settings on the Edge Pro do not take into account the blade geometry so you may not end up with an edge angle that you expect. For example, if you have a straight bevel, like a Spyderco Calypso Jr, the actual angle computation needs to factor in the wedge of the blade itself which may be another 4 or 5 degrees.
That being said, I was careful to position the Native on the flat portion of the blade so I feel reasonably confident that the resulting edge was indeed, 15 degrees per side.
My expectations were that the edge would curl when subjected to some serious cutting. The first test was slicing up a wine-in-the-box box which is stiffer than a regular box. (No snide comments from you serious wine folks, it's good for cooking.) Nice clean cut with no edge deterioration. I was surprised.
Next, I took a limb from a cherry tree I had cut some time ago with the intention of making a walking stick and whittled the bark off and generally smoothed it. Still no problems. I use newspaper as my usual test, and it still sliced the paper very nicely after the project.
Maybe the guy from Canada has something here.
I touched up the edge with a sharpmaker 204 using the gray rods in the 30 degree position and noticed two things.
a) I got a micro bevel. This suggests that either the edgepro is not precise althoght my measurements indicate that Ben Wade has a pretty good design or my Sharpmaker skills are a little off. Others may think of additional possibilities.
b) Using the famous 20X Radio Shack microscope, it appears that the Sharpmaker rods give an edge which is coarser that the DMT blue! Maybe my DMT is in need of replacement?
An aside: I sharpened up a kithen knife at a more acute angle than I normally use. Sliced a tomato very nicely but I nicked the end of my finger with just the slighest contact with the blade. Someone of my years should know better ...
I sincerely hope that others report their experiences with this approach to a good edge.
Bindlestiff
Gettng back, I understood that the basic premise of this thread was that more acute edges coupled with a coarser grind gives a better general purpose edge. Perhaps I am oversimplifying but that was the impression I got.
I tried this on a Spyderco Native in 440V, using a coarse (Blue) DMT stone mounted in my Edge Pro set at 15 Degrees. A couple of comments about that. One: I am a fan of diamond stones and by changing the length of the knob spacer to about 2 7/8", the Edge Pro holds the DMT 4" stones quite nicely. They cut faster and don't dish. Two: the settings on the Edge Pro do not take into account the blade geometry so you may not end up with an edge angle that you expect. For example, if you have a straight bevel, like a Spyderco Calypso Jr, the actual angle computation needs to factor in the wedge of the blade itself which may be another 4 or 5 degrees.
That being said, I was careful to position the Native on the flat portion of the blade so I feel reasonably confident that the resulting edge was indeed, 15 degrees per side.
My expectations were that the edge would curl when subjected to some serious cutting. The first test was slicing up a wine-in-the-box box which is stiffer than a regular box. (No snide comments from you serious wine folks, it's good for cooking.) Nice clean cut with no edge deterioration. I was surprised.
Next, I took a limb from a cherry tree I had cut some time ago with the intention of making a walking stick and whittled the bark off and generally smoothed it. Still no problems. I use newspaper as my usual test, and it still sliced the paper very nicely after the project.
Maybe the guy from Canada has something here.
I touched up the edge with a sharpmaker 204 using the gray rods in the 30 degree position and noticed two things.
a) I got a micro bevel. This suggests that either the edgepro is not precise althoght my measurements indicate that Ben Wade has a pretty good design or my Sharpmaker skills are a little off. Others may think of additional possibilities.
b) Using the famous 20X Radio Shack microscope, it appears that the Sharpmaker rods give an edge which is coarser that the DMT blue! Maybe my DMT is in need of replacement?
An aside: I sharpened up a kithen knife at a more acute angle than I normally use. Sliced a tomato very nicely but I nicked the end of my finger with just the slighest contact with the blade. Someone of my years should know better ...
I sincerely hope that others report their experiences with this approach to a good edge.
Bindlestiff
RHINOKNIVES
Gold Member
- Joined
- May 6, 2000
- Messages
- 6,344
first let me say that i flat and convex and chisel, grind only. the sectional desity of the of steel behind flats and convex has been a key factor in not getting chips out of the blade. others may (jerry hossom) get great preformance for hollows but it has not been my exspearance. as far as heavy grit edge finishes i am in this camp all the way. for my culinary knives a use a 400grit belt and on field/hunters i use 220g the mini serrations just cut, cut, cut. with a slice stroke. for the shaving sharp crowd i say yea this edge will shave the hair off your arm and take the skin too.
after i put the edge on i use a fine ceramic steel to take the wire off and then strop on leather with fabuluster compound giving a mirror at the very tip of the edge. ihave found this to prolong edge life due to less chance of deforming the very edge.
after i put the edge on i use a fine ceramic steel to take the wire off and then strop on leather with fabuluster compound giving a mirror at the very tip of the edge. ihave found this to prolong edge life due to less chance of deforming the very edge.Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Bindlestiff, thanks for providing your experience. I figured edge deformation would onset quite rapidly when I first started thinning edges as well, but was surprised. The next thing you want to try is working with some blades that are decently hard, say 62+ RC. This will allow some ultra fine edges and the cutting performance starts to get obscene.
Laurence, thanks for the description, I am always interested to hear about sharpening methods, especially from makers. Very nice knives by the way. The large bush knife has a very interesting looking handle, I have been thinking about longer handles as of late, there is a lot of flexibility there and therefore function.
-Cliff
Laurence, thanks for the description, I am always interested to hear about sharpening methods, especially from makers. Very nice knives by the way. The large bush knife has a very interesting looking handle, I have been thinking about longer handles as of late, there is a lot of flexibility there and therefore function.
-Cliff
Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Steve, as I noted in the starting post, Mike Swaim and Joe Talmadge were active proponents of this general idea on rec.knives. With Mike, it came out of his work with filed edge filleting knives in a plant if I remember correctly. Joe applied this to vast number of high end knives, and produced performance comparisions to give people an idea of just how large an effect can be made, see for example his post on increasing the performance of the Axis. Alvin Johnson also discussed in detail the edge geometry influence in cutting ability (along with hardness issues).
In addition, Lee discusses the influence of geometry and edge finish on cutting ability in his book (the complete guide to sharpening) which probably predates any discussion on rec.knives as his book was published seven years ago, and obviously wrote earliet. Swaim knew about it before that and came up with it independently, but probably didn't discuss it on rec.knives until later. JJ in his razor edge book, as well as in earlier posts on sharpening for magazines, also comments on the effect of edge geometry on cutting ability, but generally has little to say about edge finish except polish it, but this just reflects the kinds of cutting he does.
The purpose of this post was to comment on the influence that both changes have on each other as they can be made at the same time, and provide some estimates of just how large a change we are talking about. The combined effect is far greater than a simple sum, more like a multiplication (its not really, but that is the general idea). It was also to provide some information on the myth that edge holding decreases when the edge angle decreases, which is generally false (unless the functional durability of the edge is exceeded, which for most materials isn't a very high limit).
-Cliff
In addition, Lee discusses the influence of geometry and edge finish on cutting ability in his book (the complete guide to sharpening) which probably predates any discussion on rec.knives as his book was published seven years ago, and obviously wrote earliet. Swaim knew about it before that and came up with it independently, but probably didn't discuss it on rec.knives until later. JJ in his razor edge book, as well as in earlier posts on sharpening for magazines, also comments on the effect of edge geometry on cutting ability, but generally has little to say about edge finish except polish it, but this just reflects the kinds of cutting he does.
The purpose of this post was to comment on the influence that both changes have on each other as they can be made at the same time, and provide some estimates of just how large a change we are talking about. The combined effect is far greater than a simple sum, more like a multiplication (its not really, but that is the general idea). It was also to provide some information on the myth that edge holding decreases when the edge angle decreases, which is generally false (unless the functional durability of the edge is exceeded, which for most materials isn't a very high limit).
-Cliff
RHINOKNIVES
Gold Member
- Joined
- May 6, 2000
- Messages
- 6,344
on the buchwacker model the long handle lets you slide you hand back for more leverage in chopping like a hachet also it helps balance out the weight went your hand is at the front of the handle for more precise work. i have a new recurve camp/fighter design that i am working on and appying this to.
Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Laurence, good to hear, handle and a half, and double handles have a lot to offer, though their popularity is fairly low now. Finger grooves I generally stay away from however as they are too user specific, custom made of course they can indeed work very well.
-Cliff
-Cliff