Why does it seem that CBN rods do not wish to remove metal/contact edge?

[Hashishiin]

So... I have been learning to make a knife shave on the sharpmaker. That is a good feeling, but I have only been using Inox and basic carbon steel knives, wanting to master it first. Today, I thought I could make a Higonokami shave, and I tried to use my CBN rods to get a handle on the rough texture of those before I put a Spyderco to it, but it seemed to not really remove material, not enough to make it shave or anything that I noticed. Using medium stones, got it shaving no problem, "feeling" the edge no problem on the stone. Just did the same thing - nothing with CBN, razor sharp with medium, with a Gerber Dime. What am I doing wrong/not getting?

Is this just the nature of CBN, it gets a dull blade to reasonably sharp and you use higher grits from there? I feel this is not true, as I have heard 400 grit or so is all you need to really get your blade sharp, all else after is refinement of edge?

Help me out here. I am thinking of trying to sharpen VG-10, and then BD1N after I feel like doing Victorinox steel/Inox, if that's what they use? is a breeze to me, then CPM-S45VN, and then CPM-M4.

 

[Spey]

Using medium stones, got it shaving no problem, "feeling" the edge no problem on the stone. Just did the same thing - nothing with CBN, razor sharp with medium, with a Gerber Dime. What am I doing wrong/not getting?

RE: "feeling the edge no problem on the stone."

Feeling the edge is an interesting statement ...
Somewhat akin to actively increasing the angle of attack of the edge, aka dulling the geometry.

On the contrary, I would suggest that you focus on feeling the bevel, the transition to the shoulder and the approach to the edge.

Most time sharpening, I spend focused on the bevel, NOT the edge.

After distressing the edge (removing it), I build it back my removing material focused the bevel.

 

[Hashishiin]

RE: "feeling the edge no problem on the stone."

Feeling the edge is an interesting statement ...
Somewhat akin to actively increasing the angle of attack of the edge, aka dulling the geometry.

On the contrary, I would suggest that you focus on feeling the bevel, the transition to the shoulder and the approach to the edge.

Most time sharpening, I spend focused on the bevel, NOT the edge.

After distressing the edge (removing it), I build it back my removing material focused the bevel.

Man, there is a very good chance I am saying "edge" when I mean "bevel". I was hitting the correct area to make the knife sharper.

I am still picking up on all the nomenclature. How do I put it... I was trying to sharpen the knife on CBN, it was skittering down the rod, getting caught and hung up as though the rod had shoulders sometimes (this happened starting off with the medium rods too, smoothed out) and having no effect.

When I moved to the medium rod, not only was my motion way cleaner because I could feel that I was hitting the right spot, it felt right, like I was hitting a straight line every time I went down, using the Inox sheepsfoot. And when I went to test the edge, it would get sharper/shinier as I moved up to the white stones.

Removing an edge is I think too advanced for me right now, unless I sacrifice an Opinel or a RAT specifically to take the edge off and try to put one back on, which is doable.

 

[Spey]

Hashishiin,

Please understand I was NOT gigging you for nomenclature, but for feel (that tactile feel and sound you get through your fingers and or sharpening system when you're on the bevel, on the shoulder, and or approaching the edge/apex).

It is my guess that you're sharpening a knife that has both a primary and a secondary bevel where the secondary bevel is much narrower and extends to the edge/apex. Being the secondary bevel is typically quite narrow it can be very difficult to differentiate between the three areas I have mentioned.

For friends where I have tried to illustrate this it is much easier when the focus bevels are much wider. For example pick up a true Scandi grind and put it to the stone or a piece of sandpaper on a hard flat surface. Work the blade in an edge trailing direction applying pressure focused to the back side of the blade in different areas from edge to spine. The wider grind of a Scandi will help you to feel (and hear) the three areas I have mentioned and learn how to focus steel removal from the area of intended removal.

Please do not take what I have written here to believe that I am saying you should be sharpening in an edge trailing fashion (both edge trailing and edge leading are used for various reasons during sharpening process). I mentioned edge trailing in the above example as it is much easier in my mind to get a feel for what I am describing.

Many of the knives that I sharpened for others it is obvious that the person who's been maintaining the edge has been predisposed focusing on the edge as previous geometry has become blunted or steepened through their sharpening and/or stopping efforts making their knives progressively get duller with every "sharpening" they do.

EDIT: I kinda assume everyone knows about "the sharpie trick" (aka Prussian Blue or marking ink in machinist terms) as a way of visually confirming where a stone is actually contacting a blade. If not, do yourself a favor and learn about it and use it along with some type of magnification for inspection ;-) The other things I've mentioned will make much more sense.

 

[Hashishiin]

Hashishiin,

Please understand I was NOT gigging you for nomenclature, but for feel (that tactile feel and sound you get through your fingers and or sharpening system when you're on the bevel, on the shoulder, and or approaching the edge/apex).

It is my guess that you're sharpening a knife that has both a primary and a secondary bevel where the secondary bevel is much narrower and extends to the edge/apex. Being the secondary bevel is typically quite narrow it can be very difficult to differentiate between the three areas I have mentioned.

For friends where I have tried to illustrate this it is much easier when the focus bevels are much wider. For example pick up a true Scandi grind and put it to the stone or a piece of sandpaper on a hard flat surface. Work the blade in an edge trailing direction applying pressure focused to the back side of the blade in different areas from edge to spine. The wider grind of a Scandi will help you to feel (and hear) the three areas I have mentioned and learn how to focus steel removal from the area of intended removal.

Please do not take what I have written here to believe that I am saying you should be sharpening in an edge trailing fashion (both edge trailing and edge leading are used for various reasons during sharpening process). I mentioned edge trailing in the above example as it is much easier in my mind to get a feel for what I am describing.

Many of the knives that I sharpened for others it is obvious that the person who's been maintaining the edge has been predisposed focusing on the edge as previous geometry has become blunted or steepened through their sharpening and/or stopping efforts making their knives progressively get duller with every "sharpening" they do.

EDIT: I kinda assume everyone knows about "the sharpie trick" (aka Prussian Blue or marking ink in machinist terms) as a way of visually confirming where a stone is actually contacting a blade. If not, do yourself a favor and learn about it and use it along with some type of magnification for inspection ;-) The other things I've mentioned will make much more sense.

It is good you should mention scandi grinds, because a Mora Precision is one of the knives I was trying to sharpen, but that one was actually giving me some trouble. Is a Mora a true Scandi? It looks like the microbevel (I think that is what it is) on any of my other knives, but much larger. And yes, the knife I was sharpening does have a microbevel.

And, are you saying that I can dull the geometry while doing things like touch-ups on the sharpmaker, even though the knife feels sharper in the short-term?

 

[Spey]

It is good you should mention scandi grinds, because a Mora Precision is one of the knives I was trying to sharpen, but that one was actually giving me some trouble. Is a Mora a true Scandi? It looks like the microbevel (I think that is what it is) on any of my other knives, but much larger. And yes, the knife I was sharpening does have a microbevel.

And, are you saying that I can dull the geometry while doing things like touch-ups on the sharpmaker, even though the knife feels sharper in the short-term?

RE: "Is a Mora a true Scandi?"
Yes, and No (closer to No). I have had a number of Mora knives and have witnessed a number of variations on new knives that range from a blade that was ground as a "true Scandi" (one bevel extending to the apex, typically at ~10-13°per side), then put to a belt to polish and/or debur the edge resulting in Scandi Bevels that have some amount of micro-beveling (amount varies from knife to knife, which is why I would choose to hand-select a $15 knife from a display), to one's that have very little sign of any secondary grinding. The actual edge-bevel (after the micro-bevel) may range from 15-22°per side (30-45° inclusive), considerably duller/steeper the the Scandi grind primary bevels. So, some are close to a "true Scandi" some are further away.

I typically reprofile Mora's, Enzo's, etc. to have a single, flat bevel (per side) from transition to apex. It may take a couple/few sharpenings (removing weakened material near edge) before the edge becomes stable for long term use. Mora kinda forgoes this process by dumbing down the apex initially (as do most mfr's).

RE: "And, are you saying that I can dull the geometry while doing things like touch-ups on the sharpmaker, even though the knife feels sharper in the short-term?
Yes, exactly.
Unless steel is removed from the primary bevel during sharpening, you are typically effectively increasing the edge apex angle progressively dulling the geometry from the initial profiling/sharpening. Each time you "touch-up", it 'can be' sharper than just before ..., BUT the geometry will each time be slightly less acute than time before.

On the contrary, a secondary bevel that has been laid back (material removed from the shoulder transition Primary/Secondary in a flat plane) where material has been removed from the Primary Bevel will sharpen the geometry.

All of my comments so far relate to flat bevels, but would also loosely apply to say a Scandi-Vex, etc. when in proper context (removing material from the edge dulls or steepens the geometry of the Ogive (click-link), where-as removing material from behind the edge is the process of sharpening the geometry).

Back to my first post (#2);
Now knowing you already have a "Scandi" Mora, and you are aware the "Sharpie-Trick" during sharpening, I think it would be an excellent learning example for you to reprofile that Mora with the goal being to eliminate the micro-bevel. To work the steel to stone (sand-paper, etc.) focusing on removing material evenly from the bevel flats to the point you achieve a consistent bur extending ricasso to tip on both sides along with a crisp, fresh apex. Get a feel for how the blade reacts when you put even pressure on the flats (a gliding feeling), a bit of pressure back onto the transition (a skipping/drifting feeling), and how the blade responds when you put a little pressure near the edge (gets sticky on the stone). BEWARE; small amounts of material removed near edge will mean LARGE amounts of materials will need removing from the flats (loads of work added). If you've never felt/used a true Scandi, you will be in for a treat. A 12 year knife acquaintance/friend of mine recently crossed this point and has become crazy for maker-knives with Scandi grinds. He previously had negative feelings related to "Scandi" knives because of numerous experiences with Scandi+Micro versions.

EDIT: rereading your OP, that you are using the SharpMaker. Have you experimented with using the stones in the horizontal position (one or two stones) along with the Sharpie-Method ?
If not, I highly suggest you review Sal Glesser video related to using the SharpMaker in this configuration. I find it much easier to get "the feel" that I have mentioned, ESPECIALLY when sharpening Scandi profiles.

 

[Hashishiin]

RE: "Is a Mora a true Scandi?"
Yes, and No (closer to No). I have had a number of Mora knives and have witnessed a number of variations on new knives that range from a blade that was ground as a "true Scandi" (one bevel extending to the apex, typically at ~10-13°per side), then put to a belt to polish and/or debur the edge resulting in Scandi Bevels that have some amount of micro-beveling (amount varies from knife to knife, which is why I would choose to hand-select a $15 knife from a display), to one's that have very little sign of any secondary grinding. The actual edge-bevel (after the micro-bevel) may range from 15-22°per side (30-45° inclusive), considerably duller/steeper the the Scandi grind primary bevels. So, some are close to a "true Scandi" some are further away.

I typically reprofile Mora's, Enzo's, etc. to have a single, flat bevel (per side) from transition to apex. It may take a couple/few sharpenings (removing weakened material near edge) before the edge becomes stable for long term use. Mora kinda forgoes this process by dumbing down the apex initially (as do most mfr's).

RE: "And, are you saying that I can dull the geometry while doing things like touch-ups on the sharpmaker, even though the knife feels sharper in the short-term?
Yes, exactly.
Unless steel is removed from the primary bevel during sharpening, you are typically effectively increasing the edge apex angle progressively dulling the geometry from the initial profiling/sharpening. Each time you "touch-up", it 'can be' sharper than just before ..., BUT the geometry will each time be slightly less acute than time before.

On the contrary, a secondary bevel that has been laid back (material removed from the shoulder transition Primary/Secondary in a flat plane) where material has been removed from the Primary Bevel will sharpen the geometry.

All of my comments so far relate to flat bevels, but would also loosely apply to say a Scandi-Vex, etc. when in proper context (removing material from the edge dulls or steepens the geometry of the Ogive (click-link), where-as removing material from behind the edge is the process of sharpening the geometry).

Back to my first post (#2);
Now knowing you already have a "Scandi" Mora, and you are aware the "Sharpie-Trick" during sharpening, I think it would be an excellent learning example for you to reprofile that Mora with the goal being to eliminate the micro-bevel. To work the steel to stone (sand-paper, etc.) focusing on removing material evenly from the bevel flats to the point you achieve a consistent bur extending ricasso to tip on both sides along with a crisp, fresh apex. Get a feel for how the blade reacts when you put even pressure on the flats (a gliding feeling), a bit of pressure back onto the transition (a skipping/drifting feeling), and how the blade responds when you put a little pressure near the edge (gets sticky on the stone). BEWARE; small amounts of material removed near edge will mean LARGE amounts of materials will need removing from the flats (loads of work added). If you've never felt/used a true Scandi, you will be in for a treat. A 12 year knife acquaintance/friend of mine recently crossed this point and has become crazy for maker-knives with Scandi grinds. He previously had negative feelings related to "Scandi" knives because of numerous experiences with Scandi+Micro versions.

EDIT: rereading your OP, that you are using the SharpMaker. Have you experimented with using the stones in the horizontal position (one or two stones) along with the Sharpie-Method ?
If not, I highly suggest you review Sal Glesser video related to using the SharpMaker in this configuration. I find it much easier to get "the feel" that I have mentioned, ESPECIALLY when sharpening Scandi profiles.

Boy, that is a lot of interesting, informative stuff. It is a lot for me, but I think I am taking it in. I have watched about the first half of the sharpmaker video, need to sit down and take in the whole thing, evidently you can microbevel and do a proper sharpening on the sharpmaker.

No, have not tried laying the stones flat, yet. I should try with a Gerber Dime or something of the sort, though. I want to learn freehand sharpening, that would be ideal. So, does one need to take metal off of the whole knife, all the way from edge to spine, in a true sharpening? That can't be, it must only be to a certain point. I must learn what exactly these things mean.

 

[Spey]

This diagram/image illustrates a few of the common terms/nomenclatures.


RE: "So, does one need to take metal off of the whole knife, all the way from edge to spine, in a true sharpening?"

No. In example image above sharpening would involve removing steel from the Secondary Bevel (evenly and in a flat plane from the entire area of the Secondary Bevel from Ricasso to Tip and from Transition Grind-Line to Edge/Apex - actually just fwd of the Choil (I hate sharpening choils and rarely reference them, but that's just me and my experiences speaking). The Swedge )Tapered False Edge) is many times also referred to as a Tertiary Bevel (aka Third Bevel as they are typically named in order they are applied during construction).

BEWARE: in some groups the Primary and Secondary Bevel terminology is reversed (Murray Carter, West vs. East, Knife vs Cutlery, etc.), under the concept that the cutting edge is part of the Primary Bevel because cutting is the primary use. On most U.S. forums however, I find the Secondary Bevel terminology (being the Second Bevel ground to a new knife) is the one that meets at apex/edge as referenced in image above.

 

[Hashishiin]

Spey Thank you for the picture, see, this is what I mean, small discrepancies in how I referred to things. I was calling the "Secondary Bevel", the "Microbevel" or "Edge".
That clears some terms up.
Glad to see someone who doesn't need choils, because a lot of my favorite knives don't have them! I'm a big Spyderco guy. Man, I wish I could take a quick class on this, haha. I

 

[Spey]

Glad to see someone who doesn't need choils, because a lot of my favorite knives don't have them! I'm a big Spyderco guy. Man, I wish I could take a quick class on this, haha. I

Please do NOT let anyone talk you into needing to grind "sharpening choils"!##!
At least not until you have some experience with them (in-use performance).

I personally find various materials get caught up in them when using heavy pressure. They are an utter nuisance, and a poor answer to a problem that does not exist. During a reprofile of the Secondary bevel is the time to correct any deficiencies (unsharpened areas) near the Ricasso. Cold Steel and Spyderco are both guilty of not fully sharpening to the Ricasso (many other mfr's same), but at least they do NOT install choils which allows an owner to determine how to address this location as they choose.

Example: Couple weeks ago I did a first sharpening on a Para3 where I dealt with this unsharpened area just fwd of Ricasso.
The upper picture was just taken as I write this, lower pic. is from day Para3 hit the stones.
Numbers are TBE (Thickness Behind Edge at Shoulder of Primary/Secondary) prior to sharpening as a benchmark moving fwd.


EDIT: Here is an example of grinding both Primary and Secondary Bevels on a Chisel Ground Blade (with only one Primary Bevel on the opposite side).
The owners goal was to do something with scratches in the finish, my goal was to improve cutting geometry by making bevels more acute (Secondary & Primary).
I also prefer the direction of the Primary grind lines to be perpendicular to edge in the Second-Primary Bevel vs. the way Ernie does his customs.