Recommendation? Please give input on this bevel grind...

[Cushing H.]

The knife pictured below (still in progress) is a first attempt to really pull together my individual learnings so far. A Santoku, AEBL, stock thickness is 0.095". My INTENT was to grind the secondary bevel to a width of 1.14" while maintaining a clean and consistent Shinogi along the length of the blade (including uniform distance from the upswept distal end of the edge), and maintaining reasonable symmetry between the sides. Per the trigonometry, this should give a secondary bevel angle of 2.4 degrees per side) Please reference the pictures below (grind has been taken to 320 grit (Trizact A65) and then scotchbright), thickness behind edge is ~0.01":


So ... the first picture shows a shinogi about what I was shooting for. However, things somehow fell apart on the second side. Shinogi is somewhat reasonable near the tip, but (not really clear in the photo) basically disappears down near the handle ... almost like the grind is flat-full-face at that location (i definitively did NOT go for that ... and I can not seem to correct it, short of using a surface grinder to re-flatten the spine side of the blade - and I do not have one of those! ). I am not sure what happened: my best guess is a slightly off-center grind relative to the edge centerline at that location creating a MUCH smaller than expected bevel angle on that side near the handle???

So here is my question: given the geometry involved (both blade thickness and width of grind to shinogi - with the resulting small 2.4 degree per side bevel angle) are my expectations of being able go create a "clean" shinogi in this case miss-placed??? I have gone back and reviewed about 3 years of postings in "whats happening in your shop" - and upon reflection, it seems most posted knives with this basic geometry have flat-full-grinds (which would not really suffer from this defect) - maybe that is for a reason????? Most of the postings that have a nice crisp shinogi are either thicker stock, or have a significantly less wide secondary bevel (for reference, while I was grinding, I had no trouble keeping a clean "shinogi" ... but started having trouble when the bevel width became somewhat wider than 1".....).

I have fair confidence that I could walk back to a 120grit ceramic belt and convert both sides of this blade to FFG - should I do so and not attempt this kind of feat again????

(I considered doing such while grinding, but did not want to give up on the objective - and so started to attach the handle. But I am now having second thoughts, and wondering if my "objective" was miss-placed. I am pretty sure I can go back to the grind with the handle partially fitted without damaging it......)

 

[mattd]

I like the path that you are on but what you are trying to do given the target height of grind and stock thickness, is difficult. A FFG is going to cut better and look cleaner in this case. If you really want a Shinogi, you my want to try thicker stock.

 

[Natlek]

The knife pictured below (still in progress) is a first attempt to really pull together my individual learnings so far. A Santoku, AEBL, stock thickness is 0.095". My INTENT was to grind the secondary bevel to a width of 1.14" while maintaining a clean and consistent Shinogi along the length of the blade (including uniform distance from the upswept distal end of the edge), and maintaining reasonable symmetry between the sides. Per the trigonometry, this should give a secondary bevel angle of 2.4 degrees per side) Please reference the pictures below (grind has been taken to 320 grit (Trizact A65) and then scotchbright), thickness behind edge is ~0.01":
View attachment 1218453
View attachment 1218454
So ... the first picture shows a shinogi about what I was shooting for. However, things somehow fell apart on the second side. Shinogi is somewhat reasonable near the tip, but (not really clear in the photo) basically disappears down near the handle ... almost like the grind is flat-full-face at that location (i definitively did NOT go for that ... and I can not seem to correct it, short of using a surface grinder to re-flatten the spine side of the blade - and I do not have one of those! ). I am not sure what happened: my best guess is a slightly off-center grind relative to the edge centerline at that location creating a MUCH smaller than expected bevel angle on that side near the handle???

So here is my question: given the geometry involved (both blade thickness and width of grind to shinogi - with the resulting small 2.4 degree per side bevel angle) are my expectations of being able go create a "clean" shinogi in this case miss-placed??? I have gone back and reviewed about 3 years of postings in "whats happening in your shop" - and upon reflection, it seems most posted knives with this basic geometry have flat-full-grinds (which would not really suffer from this defect) - maybe that is for a reason????? Most of the postings that have a nice crisp shinogi are either thicker stock, or have a significantly less wide secondary bevel (for reference, while I was grinding, I had no trouble keeping a clean "shinogi" ... but started having trouble when the bevel width became somewhat wider than 1".....).

I have fair confidence that I could walk back to a 120grit ceramic belt and convert both sides of this blade to FFG - should I do so and not attempt this kind of feat again????

(I considered doing such while grinding, but did not want to give up on the objective - and so started to attach the handle. But I am now having second thoughts, and wondering if my "objective" was miss-placed. I am pretty sure I can go back to the grind with the handle partially fitted without damaging it......)

If =shinogi= is line between flat part and bevel then my friend you are not ready for grinding free hand .Make some jig and save that steel ...........

 

[tkroenlein]

I don't make any sort of chef knife-ry, but I think I would not even attempt a clean grind line at that shallow of an angle off the grinder with a scotchbright belt. You'll need hard backed sand paper or stones. Or at least that's what I would try.

 

[Cushing H.]

If =shinogi= is line between flat part and bevel then my friend you are not ready for grinding free hand .Make some jig and save that steel ...........

But i WANT to grind freehand

 

[HSC ///]

how many blades or bevels have you ground?
it's not that easy to do what you are asking if you are just starting out...
it can take 20-30 blade before you "get it"

how long is that blade? perhaps start with a 3-4" or 5" paring knife first?

if you don't want to give up on your objective, stop grinding knife blades and get some mild steel bars and practice grinding bevels. also that edge profile looks wonky...

specific to your question(s) -

1) "So here is my question: given the geometry involved (both blade thickness and width of grind to shinogi - with the resulting small 2.4 degree per side bevel angle) are my expectations of being able go create a "clean" shinogi in this case miss-placed??? "

creating a clean shinogi has nothing to do with your input values and calculations....create that line where ever you want it... there's no benefit to overthinking this.

2) "I have fair confidence that I could walk back to a 120grit ceramic belt and convert both sides of this blade to FFG - should I do so and not attempt this kind of feat again????"

Yes, I would, you aren't ready for that yet, you will know yourself when you are ready.

I do mostly full flat to slight convex, sometimes a customer wants a stiff spine and shinogi etc.
this is Z wear in the same thinckness as yours, grinding is not my strongest suit, often I use a hard backed bar or leather backed file with sandpaper to finish.

 

[coldsteelburns]

As mentioned, that's not an easy grind to get right and clean. It's definitely better to learn on stock at least 1/8" and up while getting use to grinding, as well as getting decent at full flats before shooting for clean and crisp saber type grinds, especially on thinner stock. That being said, a disc grinder helps keep things flat and crisp at the transitions on thinner stock, although it also takes practice to do right. I'd just take it full height and blend it in so it looks nice.

I'm the same as you when it comes to not wanting to use jigs while grinding any of my knives, but I still use files, stones, and sand paper if I need to clean something up, although it's harder to do on fully hardened blades. It's alright to be where you're at until your skills develop more, so keep on practicing fundamentals at a level easier to obtain clean results to build a proper foundation for them; it'll save time and sanity in the long run


~Paul
My Youtube Channel
... (Just some older vids of older knives I've made)

 

[John mc c]

Try an low grit aggressive stone
I went through a few before I found 1 I liked,a cheap 5 buck stone from my local hardware that is almost too aggressive,removes steel fast
Just zen out and enjoy a couple of hours on it and get your lines where you want
Plus it's one of my favourite things to do,almost as enjoyable as forging.almost

 

[Natlek]

But i WANT to grind freehand

You WANT but you CAN T and that is fact for now .Me to want but I can t so I use jig . Do whatever you want , nobody can help you here with this ,we can talk and talk but at the end you hold that knife in hand and all depends on you .Personally I hate to destroy new steel , and it is not about money . To much effort are put in that steel before you got it and to ruin it in few seconds .....

 

[scott kozub]

First off, 0.01" seems kind of thick to me at the edge for a kitchen knife. Usually I go down to 0.003" or less. That may help a little as you can chase the grind up the blade.

I'm in the same boat as you. I've only been doing this for a couple years and tried this grind early on.

These shallow angles are extremely difficult. You say you were grinding freehand? Have you tried a work rest with a push stick or your finger behind the blade? Sometimes if I need to even out a grind I mark the spot on the back of the blade where I need to raise the grind so I can vary the pressure at that spot as the blade passes by. Using the edge of the belt can also help to pinpoint where the grind is but can also turns things really bad, really fast.

You used AEB-L. Was the blade blade perfectly flat before grinding? If not you'll never get a good line.

As noted above, a jig will help and scotch bright will muddy the line.

You could make a small radius platen and give it a slight hollow grind. That will help to make the angle difference a little greater.

When doing a grind like this I find a brand new belt is an absolute essential. Get it close and then do the last pass or two with a brand new belt. It makes a world of difference. And when I say brand new, I mean a belt that has only a few passes on it. I've chased grinds like this for a while thinking I would never get it only to find a single pass with a new belt fixed it up.

If all else fails, give up on the clean line and get the bevels where you like them. Then get a heavy tape like a gorilla tap and mask the bevel. Then hand sand the flats along the blade to get a contrasting scratch pattern with a hard backer. I like the idea noted above about polishing stones.

Then if that fails, go to a FFG.

 

[Scaniaman]

As for freehanding it, I also recently got started and chose to go that way. Don't even use a work rest. I think I'm starting to figure things out pretty well after just 5-10 blades. Nowhere near perfect, but still ok. I think it is a good way to learn and comprehend this business of blade making. And it feels a little more genuine and crafty than using jigs.. But each to their own.
Practicing on mild flat bar is a good idea, but I lost patience after a few of those.

 

[Fred.Rowe]

Knifemakers, keep in mind it's the results that are on display, not how the results were come by. Don't start out learning to make knives, hamstringing yourself by thinking there is but one way to be successful; there are many.
If you were apprenticing at my shop and wished to make this knife, I'd start out with materials choice and then put together a plan where you will have the best chance of being successful, using the tools and skills we have on hand. After all, success is the goal.
Happy Grinding, Fred

 

[Cushing H.]

I believe I was not clear in what I was asking, and has led to some variation in the types of responses. I was not asking whether I was "ready" to try this .... after all you never really know you are "ready" to do something until you try it (and succeed!) ... rather I was really asking whether achieving a clean shinogi with this low an angle bevel is (or should be) "somewhat easy" or "DIFFICULT" (something "difficult" presumably being achievable with lots of practice. HSC - respectfully, I somewhat disagree with your statement that "a clean shinogi has nothing to do with your input values". I believe you are thinking from the perspective of a craftsman versus acquired skills. For me, this is a mathematical issue: for my blade thickness, the relationship between grind angle and grind width is a nonlinear trigonometric relationship:

Things drop off quickly to small angles pretty quickly as you make that bevel wider. If you will allow me to say that smaller angles require more "care" to create a "clean" shinogi on a grinder (due to a lot of reasons: variation in belt grit size, influence of blade flatness (as Scott pointed out), lack of consistent "flatness" of the belt on the grinder, lack of ability to hold a clean angle of blade to belt, or the spark that got under my fingernail while making one pass causing a "flinch" (ouch!) ... then I would ask you to allow that a clean shinogi does have something to do with the input values. Like I said, things were just fine until I worked down to a grind width a little more than an inch, then things somewhat fell apart.

I think my takeaway from all the comments here is that my expectation of getting a clean shinogi off a grinder with this width grind WAS misplaced (but I had to at least try, and I know I learn by doing - and often learn the most by failing!) ... and that, even under the best circumstances a clean shinogi with this kind of geometry will need hand finishing with flat, hard backed materials (sandpaper, stone, etc). That is a lesson I will take forward - not sure if I will ever get to the point that I want to try that again (but you never know). HSC, after my trying this, I am extremely impressed with the result you achieved with the Gyuto you posted - that took a lot of skill and patience to achieve!

Some here have spoken in a way that sounds like "dont do something until you are ready", or "dont waste your time on that at this point" ... kind of as if the perspective being used is that "if you dont get the outcome you tried for you have failed and wasted your time", or "you have wasted that material". For me (and I suspect a few others who have responded here), the point is NOT the outcome, it is what I have learned along the way. Here, I did not succeed in my clean shinogi, but I have learned (with your input) a lot more about what it takes to achieve one given different geometries. I always had in the back of my mind that my fallback here was a full flat grind - which will be just fine for this knife! (and will allow me to get that TBE thinner, as I do know 0.01" is thicker than optimal). I think this is more or less what Fred Rowe was saying in his response - I do appreciate his perspective. (though the choice of material here was more or less defined by the practices of the person this knife is for ... and the fact that JT could cut out the profile foe me!). I'll post the final result in the "whats happening in your shop" thread".

(oh ... and re. "freehanding" versus "jigs" ... I long ago decided I would go for the freehand approach, if for any reason because that is just what I wanted to do! A lot of that approach now feels quite comfortable to me, and using a jig I think would make me feel "out of contact" with the work. to each his own....)

Thank you all again for the input and insights - I continue to learn from them!

 

[Natlek]

. If you will allow me to say that smaller angles require more "care" to create a "clean" shinogi on a grinder (due to a lot of reasons: variation in belt grit size, influence of blade flatness (as Scott pointed out), lack of consistent "flatness" of the belt on the grinder, lack of ability to hold a clean angle of blade to belt, or the spark that got under my fingernail while making one pass causing a "flinch" (ouch!) ... then I would ask you to allow that a clean shinogi does have something to do with the input values.

Angle my friend it is always about angle nothing else .It is hard to keep constant angle + constant pressure when you grind thin blade and LOW angle free hand even for master .... This is 1.5 mm thick steel .I can t find better picture of other knife now with higher grind on same thickness steel but believe me that Shinogi is clean as it can be .But I use jig as I already say .And I would like to see video how someone grind that free hand ...BUT to show us every pass he make till he finish it , anyone !

 

[Maelstrom78]

Another thing is that knives will likely have/need a distal taper. Along with the various curves you are unlikely to make a knife with a constant angle from heel to tip. The more freehand grinding you do the more you will notice yourself doing various rotations on things.

 

[Mecha]

I believe I was not clear in what I was asking, and has led to some variation in the types of responses. I was not asking whether I was "ready" to try this .... after all you never really know you are "ready" to do something until you try it (and succeed!) ... rather I was really asking whether achieving a clean shinogi with this low an angle bevel is (or should be) "somewhat easy" or "DIFFICULT" (something "difficult" presumably being achievable with lots of practice. HSC - respectfully, I somewhat disagree with your statement that "a clean shinogi has nothing to do with your input values". I believe you are thinking from the perspective of a craftsman versus acquired skills. For me, this is a mathematical issue: for my blade thickness, the relationship between grind angle and grind width is a nonlinear trigonometric relationship:
View attachment 1219001
Things drop off quickly to small angles pretty quickly as you make that bevel wider. If you will allow me to say that smaller angles require more "care" to create a "clean" shinogi on a grinder (due to a lot of reasons: variation in belt grit size, influence of blade flatness (as Scott pointed out), lack of consistent "flatness" of the belt on the grinder, lack of ability to hold a clean angle of blade to belt, or the spark that got under my fingernail while making one pass causing a "flinch" (ouch!) ... then I would ask you to allow that a clean shinogi does have something to do with the input values. Like I said, things were just fine until I worked down to a grind width a little more than an inch, then things somewhat fell apart.

I think my takeaway from all the comments here is that my expectation of getting a clean shinogi off a grinder with this width grind WAS misplaced (but I had to at least try, and I know I learn by doing - and often learn the most by failing!) ... and that, even under the best circumstances a clean shinogi with this kind of geometry will need hand finishing with flat, hard backed materials (sandpaper, stone, etc). That is a lesson I will take forward - not sure if I will ever get to the point that I want to try that again (but you never know). HSC, after my trying this, I am extremely impressed with the result you achieved with the Gyuto you posted - that took a lot of skill and patience to achieve!

Some here have spoken in a way that sounds like "dont do something until you are ready", or "dont waste your time on that at this point" ... kind of as if the perspective being used is that "if you dont get the outcome you tried for you have failed and wasted your time", or "you have wasted that material". For me (and I suspect a few others who have responded here), the point is NOT the outcome, it is what I have learned along the way. Here, I did not succeed in my clean shinogi, but I have learned (with your input) a lot more about what it takes to achieve one given different geometries. I always had in the back of my mind that my fallback here was a full flat grind - which will be just fine for this knife! (and will allow me to get that TBE thinner, as I do know 0.01" is thicker than optimal). I think this is more or less what Fred Rowe was saying in his response - I do appreciate his perspective. (though the choice of material here was more or less defined by the practices of the person this knife is for ... and the fact that JT could cut out the profile foe me!). I'll post the final result in the "whats happening in your shop" thread".

(oh ... and re. "freehanding" versus "jigs" ... I long ago decided I would go for the freehand approach, if for any reason because that is just what I wanted to do! A lot of that approach now feels quite comfortable to me, and using a jig I think would make me feel "out of contact" with the work. to each his own....)

Thank you all again for the input and insights - I continue to learn from them!

Try using just the very edge of the grinding belt like a laser (assuming you're using the whole flat of the belt).

 

[Kessik221]

"Power tools make quick work but also destroy work just as quickly" - unknown. Looks like you could easily line those up with a few hours of hand sanding. It would also even out the side you liked. The difference in sides looks to me like a little variation in grip and angle on your left hand when grinding.

 

[Cushing H.]

Natlek - if i understand you correctly, you are saying that a low angle grind like this is difficult enough that a master would be challenged to do it freehand, and that a jig makes a huge difference. Is that a correct understanding of what you are saying? If so, fair enough!

 

[Cushing H.]

"Power tools make quick work but also destroy work just as quickly" - unknown. Looks like you could easily line those up with a few hours of hand sanding. It would also even out the side you liked. The difference in sides looks to me like a little variation in grip and angle on your left hand when grinding.

Lol. The funny thing is that the “not so good” side of the blade was on my “good” handed side (i am right handed). Maybe this points to some more subtle issues like non-flatness of the blade?

i dont know... maybe i will eventually come to the point where i will say “i am going to hand sand” ... at which point you all have a right to lay in to me, and i will bow to all of you, and grin and bear it.

(for reference, i did convert the blade to ffg , about 45 minutes of effort, (still not perfect) and showed it to my wife, who said “so what is wrong with this”? Know that you people have perverted my sense of what is “good enough”. . )

 

[Natlek]

Natlek - if i understand you correctly, you are saying that a low angle grind like this is difficult enough that a master would be challenged to do it freehand, and that a jig makes a huge difference. Is that a correct understanding of what you are saying? If so, fair enough!

Yes , that's exactly what i mean .Thin blade /1.5mm / and high bevels , i challenge everyone to show us that I'm wrong .