Angle vs Result

[Its_Raw]

In a past life of running a business dealing with machining metal and precise measurements, I am having a bit of trouble getting over the obsession of needing to know the precise angle of the edge and whether or not it should be 16-degrees, 20-degrees, etc. I am getting OK sharpening free-hand, but I am not sure the angle, though it is somewhere between 15- and 18ish- degrees. Should I get over the angle obsession and focus on the results or should I stick with trying to get precise angles? How does that transfer to a pocket knife that might need a 20 +/- degree angle verses a lower angle kitchen knife?

Thank you!

 

[HumbleHomeCook]

Yep, get over it. With freehand sharpening it won't stay precise all the way down the edge and on both sides anyways. I work with ultra-high purity metal (5 and 6N's) and insanely tight specs all day every day but I don't care about the exact angle on the edge of my knives. I used to but it didn't last long.

Other than basic technique, it's kinda hard to compare kitchen and EDC type cutlery. Kitchen knives typically have a very thin edge, often of sharpener friendly steel, and in general a thinner profile and the intent of slicing. EDC stuff is generally much thicker by comparison, often uses more challenging steels and is typically called upon for rougher work.

If you want to try to approximate the factory angle, get a red Sharpie and paint the edge. That will give you a feel for what they did. Beware that many pocket knives, even from the big names, have pretty terrible edge grinds when you start inspecting them.

As you've found, I think most us fall into a natural freehand angle of around 15ish degrees. I generally apply that to all my knives regardless of the type and then let the knife and tasks tell me if I need to adjust.

 

[refcast]

Angle doesn't matter toooo much. Here's a flowmap for example:

1. What grit
A. Edge completely rounded? --> start at coarse stone 220-500 grit

B. Edge just dull? --> start at 1000 grit

2. What angle
Look at the angle on the knife and match it if you want the same angle. Rock the knife edge at an angle gently on the stone and feel which angle feels slightly more secure. This is easiest with larger bevels sizes -- which is too thick for normal use. Look at the bevel to see old scratch pattern from previous edge. Sharpen a little with angle you choose and look

A. If new scratch pattern is above the old bevels, then lower the angle until the new scratch pattern lines up on top of the old scratch pattern.

B. If the new scratch pattern is closer to the edge, and doesn't cover the old scratch pattern completely, lower the angle until the centers line up, or the new scratch pattern on the edge bevel covers the old one.

3. Sharpen both sides until a small consistent burr, using outlined process.

4. (Optional) Does the knife cut with the amount of resistance and stability you want for the task?

A. Too much force required. Lower the sharpening angle and thin behind the edge so there's less cutting force needed.

B. Too easy to cut, it feel fragile. Increase the edge angle

Faq:

1. Is it bad if I have too high of an angle?
The knife reprofiled faster, loses height faster, gets thicker cross sectional geometry (less chipping, more resistance in food). This can be good to change the profile, increase toughness, remove chips. All sharpening reduces the overall life of the knife, but knives need to be sharp to work, so try to strike a compromise on how much to sharpen.

2. Is it bad if I have too low of an angle?
A lower angle thins the knife and makes it easier to move through food. If it scratches the blade face much higher than the edge bevel, thats usually too low of an angle. A little bit above the edge is fine. You can continue it to set a new lower edge angle. Or sharpen it without creating a burr, which thins the knife and makes cutting smooth without changing the edge angle. Thinning lets the knife cut well with less force, so it's a good thing to be able to do.

3. Is it bad to not have a precise angle?
Not the biggest issue. Just feel that the edge everywhere is sharp. Of course if you want better and better edge results, being able to hold a consistent angle is important. But being able to hold a 18 vs 19 degree angle doesn't matter too much, compared to a generally high or low angle for toughness or sharpness. Or more importantly, making a clean apex at whatever angle you choose, which you can test with paper, hair, finger feeling, etc, and inspect visually or even microscopically

For pocket knives overall geometry doesn't seem to be as vital, but same applies.

 

[1315]

Pause for 20 seconds before grinding and focus on having a good grip and hand positioning, the goal being consistency. "The hold" was key for me in gaining consistency thru the "heel to tip" draw, and the sharpie + magnification can guide you. Then, focus on pressure, and using appropriate pressure given the stone, as you continue.
In short, consider angle, but channel it into consisteny and more focus on pressure/reading the stone.

 

[Mr.Wizard]

The importance of edge angle has been quantified, so you don't have to wonder. From @Larrin on https://knifesteelnerds.com

TCC (mm) = -157 + 15.8*Hardness (Rc) – 17.8*EdgeAngle(°) + 11.2*CrC(%) + 14.6*CrVC(%) + 26.2*MC(%) + 9.5*M6C(%) + 20.9*MN(%) + 19.4*CrN(%)

"Edge angle had by far the strongest effect on edge retention, much stronger than other effects such as PM vs ingot and the finish it was sharpened to. Here are graphs showing the performance of 20, 34, and 50° vs cut length for an individual cut and also for total card cut in mm:"

 

[RDalman]

It was kindof said already but your final edge setting/deburring should not be lower than 15 (30 incl) imo. Before/above that you should adjust to YOUR use with the tool, thinning or thickening near edge. For myself I probably do around 20 deg microbevel, but keep it really thin above. The Larrin-test shows importance of thinness imo, but doesn't go into the kind of detail on thinner geometry most of us here are interested in.

 

[big D]

Follow the angle of what is on the knife until you find/think, there is a reason to make an adjustment. I couldn't begin to tell you the angle on any of my knives, I simply find them. Some I have thinned and therefore increased the angle. Another rather than thinning at the moment, I simply lowered the edge angle. Some have broached finding an edge. If you are freehand sharpening, (not a jig) and wish my input, just ask.
Was edited

 

[mengwong]

the obsession of needing to know the precise angle of the edge

Fun toy:
https://www.catra.org/testing-equipment/catra-goniometers/hobbi-goniometer/

 

[Deadboxhero]

In a past life of running a business dealing with machining metal and precise measurements, I am having a bit of trouble getting over the obsession of needing to know the precise angle of the edge and whether or not it should be 16-degrees, 20-degrees, etc. I am getting OK sharpening free-hand, but I am not sure the angle, though it is somewhere between 15- and 18ish- degrees. Should I get over the angle obsession and focus on the results or should I stick with trying to get precise angles? How does that transfer to a pocket knife that might need a 20 +/- degree angle verses a lower angle kitchen knife?

Thank you!

Freehand produces convexity, you're never going to get an exact angle with that method and that's not what is holding you back.
Free handing is about consistency and good consistency will naturally blend the angles from the shoulder of the bevel to the apex. (Not blending into the grind)


If you're still not getting good results, it means your deburring game needs some love.

If you can't produce a sharp edge at low grit, there's a good chance your angle consistency and deburring needs review.

 

[Deadboxhero]

About Laser Goniometers


A lot of folks here would probably poop themselves if they saw what angles they are ACTUALLY creating rather what they are imagining.

A lot of 10dps chest beating, machismo is going to evaporate when guys see some laser reflection patterns on that "10dps" showing +20dps.

Things are not what they seem, without measurement, we don't know what the exact degrees the edge angle is at the actual apex.


Such is the wonder of measurement rather than "imagament"

A laser goniometer requires at least a ~400 grit edge finish with consistent scratch pattern to accurately measure the angle. Freehand will show up as a "dash" rather than a "dot" since an exact angle is not being held, which is fine, it's better to have a consistent blending of angles from bevel shoulder to the tip of apex that's perfectly deburred rather than a "perfect angle" that's got a big fat burr hiding at the apex.

That's why just using a jig sharpener and having a perfect angle doesn't translate to sharp.

Deburring is what separates the wheat from the chaff.

 

[captaincaed]

I agree 100%. After starting on razors I feel like I haven’t really known anything about sharpening for years. Nothing like the skin covering your jugular reminding you that you didn’t do a good enough job deburring, and now you’re paying for it.

A good, clean edge will pop hair at 400 grit, and easily shave hair (blade on skin) at 1000 grit. This is off the stone, with some soft-media deburring (no diamond sprays, pastes, or other abrasives disguised as ‘strops’).

To the original question about angle. I got a knife from a reputable maker with a beefy grind. It was a good, high quality workhorse grind. But it was beefy. Would not hold a toothy edge to save its life. I asked for it to be thinned. After thinning it felt like a whole new knife. That dramatic reduction in primary grind angle allowed a much more acute sharpening angle. Now it cuts like a demon and holds the kind of toothy edge I like in the kitchen an order of magnitude longer than before. I owned and used the knife for a year before asking for the regrind, and asked the maker to put an edge back on it. We both couldn’t quite get it there. It really was the angle at the end of the day. Steel and heat treat were the same. Stones were the same, sharpeners were the same.

It’s a real factor. You do need to tailor the angle (in broad strokes) to meet your cutting needs. But thinner is better. Make it thin until normal use chips it, then back off a degree or two, but not more. That is “just right”. The angle DOES matter, but the number doesn’t, if that makes sense.

 

[Its_Raw]

Man, that is a lot of good information! I have been a lousy woodworker for years and I can sharpen a plane blade and a chisel to an extremely sharp edge, but I have guides for those and I do not do it freehand. With the higher grits, I am getting a really sharp, hair-shaving edge, but not with the 400-grit stone. I will pay more attention next time with the lower grit. The chef’s knife I sharpened easily glides through tomatoes and I am happy with the performance - but, I do not know what really sharp is when it comes to cutting vegetables as I am new to cooking (Mrs took care of it for years while the kids were at home).

 

[captaincaed]

You're going to do fine. It takes a bit for a new paradigm, but the skill comes. I was also a lousy wood worker for years before turning into a lousy knife sharpener.

Your experience may differ, but one of the biggest differences I find is that I like a toothy edge on the kitchen since I'm doing more draw cuts. For chisels and planes I want a pretty refined edge since I'm making push cuts for a clean surface finish. 1-2k edges in the kitchen, well deburred, can be a great starting place.

To be fair a 400 grit hair popping edge takes some real practice (and I'm not great at it, but it definitely can be done). But 1k shaving shouldn't be too bad.

 

[HumbleHomeCook]

Man, that is a lot of good information! I have been a lousy woodworker for years and I can sharpen a plane blade and a chisel to an extremely sharp edge, but I have guides for those and I do not do it freehand. With the higher grits, I am getting a really sharp, hair-shaving edge, but not with the 400-grit stone. I will pay more attention next time with the lower grit. The chef’s knife I sharpened easily glides through tomatoes and I am happy with the performance - but, I do not know what really sharp is when it comes to cutting vegetables as I am new to cooking (Mrs took care of it for years while the kids were at home).

Good for you jumping in on both the sharpening and the cooking. Much fun to be had in both and being an empty nester opens up a lot of potential (I know).

I would offer this, there are two types of sharpening.

1. Practical performance. This is the path most of us walk. It means not going to very high grits, may or may not slice paper towel, but provides excellent performance in the kitchen. With performance meaning both in terms of slicing and edge retention.

2. Personal pride. This is the path for just really seeing what you can accomplish. This is striving for hair-whittling, atom-splitting edges and obsessing over every detail.

Sure there's overlap between the two but you get the idea. I know my limitations and with freehand sharpening I stay mostly in category one. That isn't to say knives in that category aren't very sharp, they are, but they aren't on the same plane as those done well in category two. It's fun to pursue both if you want. The only point I have in that is that it's okay if your daily driver isn't named Oppenheimer.

 

[ethompson]

Deburring is what separates the wheat from the chaff.

Amen.

In my personal experience, if I've done a good job deburring on stones it really doesn't matter what grit I finish at, 400 or Nakayama, the edge will be satisfactory for kitchen use and stay that way for a good amount of time. I find it harder to deburr without just burnishing the edge or creating a micro-foil edge once I get above 4k or so, but when I do manage it I have no problems with toothy edges. A strop can definitely help, I use them frequently, but my best edges have all been stone fresh.

 

[Its_Raw]

Being motivated after reading all of the good information above, I decided to go after another cheap chef's knife. I struggled a bit more tonight than the other day. I noticed from the width of the angle of one side of the knife to the other, I was keeping a fairly decent angle pulling the knife toward me, but a much higher angle when pushing the knife away. I will have to be very cognizant of that next time. I also noticed I was getting not so great results toward the handle of the knife - kind of in the flat area. In the end, the knife felt sharp, but snagged in a couple of spots when cutting paper, and the back end of the blade tore more than cut.

I noticed some faint gouges in the stone from dragging the tip of the knife at the end of the stroke. Nothing using the stone will not remove and they are not visible when the stone is dry and I have to really feel around for them to find them. Any suggestions?

Thank you!

 

[panda]

Amen.

In my personal experience, if I've done a good job deburring on stones it really doesn't matter what grit I finish at, 400 or Nakayama, the edge will be satisfactory for kitchen use and stay that way for a good amount of time. I find it harder to deburr without just burnishing the edge or creating a micro-foil edge once I get above 4k or so, but when I do manage it I have no problems with toothy edges. A strop can definitely help, I use them frequently, but my best edges have all been stone fresh.

I've been using ONLY chosera 400 for the past 3 years lol

 

[mengwong]

I was keeping a fairly decent angle pulling the knife toward me, but a much higher angle when pushing the knife away.

I do this sort of convexing deliberately, but reversed, so the apex sees edge leading strokes while the shoulders see edge trailing.

I noticed some faint gouges in the stone from dragging the tip of the knife at the end of the stroke. Nothing using the stone will not remove and they are not visible when the stone is dry and I have to really feel around for them to find them. Any suggestions?

The perfect excuse to shop for an Atoma 140 or one of the $$$$ options from Nano-Hone!

Gouges don’t really matter, they’re below the surface.

 

[Its_Raw]

I keep hearing about the Atoma. I am going to need to invest in one. I am looking at them now online. So, do they have replaceable "diamond sheets," or are the sheets something different? https://www.sharpeningsupplies.com/Search.aspx?k=atoma

And it took me a second to figure out what was the "shoulder," but I understand now. I I need to clarify my "technique" (very poor choice of words). I only touch the stone in one direction. I definitely do not have the back and forth thing down. So I pull the knife towards me while sharpening the right side of the knife, and push it away from me when sharpening the life side.

 

[Its_Raw]

Is this the same diamond plate from Atoma for a lot less than the one sold at Sharpening Supply?

https://www.amazon.com/Atoma-Diamon...b_tag=se&keywords=Atoma&qid=1709386457&sr=8-1

 

[Justinv]

You can get generic plates too for much less. cktg has one for $30 for example.

 

[Its_Raw]

Having no experience in either, is there a difference in longevity of the plate between the two?

 

[Justinv]

I was keeping a fairly decent angle pulling the knife toward me, but a much higher angle when pushing the knife away. I will have to be very cognizant of that next time.

Initially you won’t have good feel but with practice you can feel when the sharpening angle matches the existing edge angle.

If you go back and forth at too low an angle it skates across the stone. If you increase the angle a bit and you start feeling a bit of resistance from the edge on edge leading strokes you are at the right angle.

You will also hear the difference on a stone with decent feedback. You can hear on edge trailing or edge leading strokes.

All this takes experience to get dialed in so keep at it. Eventually you just automatically get it to the right angle after a stroke or two without thinking about it.

 

[Justinv]

You get better feedback if its somewhat sharp. If its super dull you won’t get as much feedback. If it kinda cuts paper but not paper towel its a good time to sharpen.

 

[mengwong]

So, do they have replaceable "diamond sheets," or are the sheets something different?

The sheet / plate is a thin piece with diamonds. Its job is to flatten.

The base is a cuboid of aluminium. Its job is to be flat.

Assuming you haven't got one of the ones with a handle, then Atoma plates are two sided. Wait for the 400 to get slightly worn in, then buy a replacement 140 sheet, stick it on the other side, and you've got the perfect flattening and conditioning combi. I've got three or four of these 140x400s, and I use them every day

 

[Blank Blades.]

About Laser Goniometers


A lot of folks here would probably poop themselves if they saw what angles they are ACTUALLY creating rather what they are imagining.

A lot of 10dps chest beating, machismo is going to evaporate when guys see some laser reflection patterns on that "10dps" showing +20dps.

Things are not what they seem, without measurement, we don't know what the exact degrees the edge angle is at the actual apex.


Such is the wonder of measurement rather than "imagament"

A laser goniometer requires at least a ~400 grit edge finish with consistent scratch pattern to accurately measure the angle. Freehand will show up as a "dash" rather than a "dot" since an exact angle is not being held, which is fine, it's better to have a consistent blending of angles from bevel shoulder to the tip of apex that's perfectly deburred rather than a "perfect angle" that's got a big fat burr hiding at the apex.

That's why just using a jig sharpener and having a perfect angle doesn't translate to sharp.

Deburring is what separates the wheat from the chaff.

Oh no shawn said i need a goiniometer to sharpen my knife!

The importance of edge angle has been quantified, so you don't have to wonder. From @Larrin on https://knifesteelnerds.com

TCC (mm) = -157 + 15.8*Hardness (Rc) – 17.8*EdgeAngle(°) + 11.2*CrC(%) + 14.6*CrVC(%) + 26.2*MC(%) + 9.5*M6C(%) + 20.9*MN(%) + 19.4*CrN(%)

"Edge angle had by far the strongest effect on edge retention, much stronger than other effects such as PM vs ingot and the finish it was sharpened to. Here are graphs showing the performance of 20, 34, and 50° vs cut length for an individual cut and also for total card cut in mm:"

Edge angle has a quantifiable effect on how a knife dulls from wear.

If the knife is dulling from a different mode of failure, then it gets more complicated.

Obviously some people have mentioned it already. But its going to matter what the steel is, on whether or not it will have the edge stability, to be able to handle very low angles without rolling, and toughness to avoid chipping or microchipping (microchipping might be unavoidable for some steels, but its better than rolling at least).

The task its getting used for will also need to come into play. If its an edc, and the person only cuts cardboard, a super low angle could be fine. If they're hammering the edge into things, maybe not so fine. For a kitchen knife it can be similar.

All this is to say, edge angle is going to be a tradeoff between higher initial sharpness, and more edge retention against wear, vs dulling through deformation or chipping. And the only way to know what angle is best is applying it to a specific knife and application.


With that novel out of the way, i freehand. So i just make rough adjustments i feel a certain angle isn't working for me.

 

[The Forest Ninja]

I know it's sharp when a gentle touch draws blood.

 

[Its_Raw]

For flattening, I have a heavy piece of plate glass and a plethora of wet/dry paper. I have used that in the past to flatten stones. Is that sacrilegious to do for better stones?

 

[mengwong]

The higher ascetics forgo the paper and use only the sand.

loose SiC powder/water on a piece of glass, tile, etc

 

[Its_Raw]

Wet/dry paper is all I have at this time, is it OK to use? And thank you for all of the help!