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Sharpening Knives. To Microbevel or Not to Microbevel!


xraymymind
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I thought it would be interesting to have a discussion about knife sharpening. Personally, I sharpen my knives with a slightly curved edge.

However, I've never been quite sure whether to put a micro-bevel on knives or not. I grind my Plane blades & Chisels with a 25° bevel, and then hone with a 30° microbevel. On my knives (at present), I have a single bevel. But I always wonder whether it might be better to put a slightly raised microbevel on these too - it'd certainly save time when I re-sharpen them.

It would be interesting to hear what works for YOU in regards to knife sharpening, and whether you sharpen knives with a single flat bevel, or with a raised microbevel.

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Nice topic. I use a flat bevel w/o a micro-bevel. Mostly because I sharpen my knives by hand, and I use a sharpening jig for putting micro bevels on plane irons. 
 

Another shape you didn’t mention that some folks use for knives are apple seed shaped bevels. 

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24 minutes ago, Jim Bress said:

Nice topic. I use a flat bevel w/o a micro-bevel. Mostly because I sharpen my knives by hand, and I use a sharpening jig for putting micro bevels on plane irons. 
 

Another shape you didn’t mention that some folks use for knives are apple seed shaped bevels. 

Cheers Jim! Like you, I also use a Sharpening Jig (an Eclipse guide) for my Micro-bevels.

I have heard of people avoiding Micro-bevels on their plane irons & chisels as they are 'unrepeatable'. But this only applies if one sharpens freehand. If one uses a jig, you can even have two Micro-bevels, which are perfectly repeatable, every time. David Charlesworth (cabinet-maker and teacher) grinds his Plane blades at 25°, raises a wire edge on a 1,000 grit stone at 33°, and polishes the edge on a 8,000 grit stone at 35°. This results in a mightily sharp edge.

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I would take into account the steel being used.  Some steel chips or the sharpening burr "peels off" if you have have too fine of an edge. 

This may simply be a function of being an amateur with "mixed" tool quality.  My Stubia gouges hold a very fine edge.  My Swissmade are hit or miss.  My Chinese no-name (very good nonetheless) are finicky.

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I've had a hard time learning how to work with knives. I used to sharpen a micro bevel as it is a natural way to get things really sharp but I was always frustrated that I couldn't work with the accuracy and precision I wanted with a micro bevel. Like Jim, I now sharpen knives with a flat bevel only. I use straight knives with a sort of shearing motion (not sure if this is the right word)-- drawing the bevel down and forward along the wood face i'm trimming. It helps improves accuracy (for me at least) 

l'd really like to hear from others on this topic as well

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When using a knife with a flat side and a bevelled side it will perform in much the same way, with or without a micro bevel, except a micro bevel provides a bit of clearance to change the cutting angle. The down side is that the knife will tend to dig in and jam either way.

So I think it best to sharpen the bevelled side freehand at a slightly higher angle. That will result in a slightly rounded bevel and that will allow more flexibility in the angle of attack when cutting into tight corners and also prevent jamming.

And the flat side can be used in situations like cutting purfling channel bee stings.

I've just ground a bevel on one of the knives I've made at a little less than 15 degrees. I had previously ground it at a slightly higher angle and sharpened it and the edge held up apart from a tiny overheated spot on the edge.

I'm going to resharpen it and see how the edge holds up.

I don't know what angle violin knives are generally ground at but I've now come to the conclusion that anything over 20 deg. after hand sharpening is too high, especially used when cutting across the grain.

 

 

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To me the term micro-bevel means a small, precise, jig-produced, flat bevel applied after grinding the main bevel.

As a general rule it is logical to keep the sharpening bevel narrow. That  means lightly regrinding the main bevel regularly before resharpening, especially with plane blades. And using a jig to sharpen those that way should not be a problem.

However, all hand-held tools such as chisels, gouges and knives need slightly rounded bevels to work properly. Especially gouges, which should have a smooth, slightly rounded bevel extending back from the cutting edge.

 

 

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22 minutes ago, Dennis J said:

To me the term micro-bevel means a small, precise, jig-produced, flat bevel applied after grinding the main bevel.

Why micro bevel if the main bevel is flat?

As a general rule it is logical to keep the sharpening bevel narrow.

general rule ? Just trying to understand.

That  means lightly regrinding the main bevel regularly before resharpening, especially with plane blades. And using a jig to sharpen those that way should not be a problem.

That sounds like a lot of extra work,, and I don't like extra work.

However, all hand-held tools such as chisels, gouges and knives need slightly rounded bevels to work properly.

Now this one I really don't get. It sends me out to space with no way to get back home.

Help please?

Especially gouges, which should have a smooth, slightly rounded bevel extending back from the cutting edge.

Now I'm still lost,,,

Why do you believe this?

Could this be because of your personal working methods,

I'm ready to learn.

 

 

 

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On 6/12/2021 at 5:34 PM, Peter K-G said:

I'm simple, so I just make knives, gouges and plane blades sharp, so they cut wood. If it doesn't cut wood it's not sharp enough.

 

13 hours ago, Dennis J said:

However, all hand-held tools such as chisels, gouges and knives need slightly rounded bevels to work properly. Especially gouges, which should have a smooth, slightly rounded bevel extending back from the cutting edge.

Same comment for both - I don't think it is simple at least for me - rounded bevels on gouges  and knives can be razor sharp and cut wood but I find dubbed bevels change the 'geometry' of these tools in a manner that makes it difficult (for me at least) to control for precision work. 

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Carving gouges should have only one continuous, slightly curving bevel extending smoothly from the cutting edge to the heel. In other words the bevel should be slightly convex or domed. I aim to grind that bevel at less than about 25 degrees.

It is important to avoid increasing the cutting edge angle in the final stages of sharpening with finer stones. The whole bevel needs to be reduced to avoid that and it takes time.

Shaped like that the gouge will cut with a scooping action. If you use a mallet and hammer a gouge into a piece of wood at the right angle it should cut down and then up out of the cut if the bevel is properly shaped.

Chisels, plane blades and knives can be hollow ground close to the cutting edge and sharpened with fine grit stones.

The main reason for keeping the sharpening bevel narrow by that way is that wider bevels, say more than 3 mm,  don't readily sharpen with stones less than 1000 grit. Especially with steels rated at 62 Rockwell or more.

A narrow bevel can be quickly sharpened with 1000 and 4000 grit stones by hand. That bevel will be slightly rounded so that when used bevel down it will cut smoothly.

I lightly regrind chisel and plane blade main bevels every few sharpenings to prevent the sharpening bevel getting wider than about 2-3 mm. Only takes a couple of minutes and reduces sharpening time.

I also lightly hollow grind gouges before sharpening. It speeds up the sharpening process by reducing the surface area. It doesn't have to be a deep hollow grind.

I have chisels and gouges well over 60 Rockwell. It is simply impossible to quickly hand sharpen a chisel blade which might have a bevel 8 mm wide with stones finer than 1000 grit without increasing the sharpening angle. So at each successive sharpening the cutting angle is increased. And grinding regularly will preserve the cutting angle where it needs to be.

 

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Still not feeling it.

Eventually my gouges get rounded from sharpening.

Then when I start feeling like a drunk, wobbling around,,nibbling and digging at things,,  messing things up,, and getting impatient just farting around, digging at the wood without any control whatsoever, and after I've grabbed every last gouge and they all are shot,, nothing left but rounded micro bevel upon rounded micro bevel worn out useless garbage I quit!!

They are as sharp as a razor guaranteed,, just worthless to me.

There is nothing left to register the cut,,,you know,, register the blade to the work piece. 

It all just becomes guess work from that point,, shooting in the dark in a blinding sandstorm.

Then,,, I get out the tormac and give them a nice hollow ground edge and man does that work great, I get with the program,  with a lot of delicate and precise control, huge shavings, it is suddenly fun again. I can work fast, I quit ruining things, and BANG! we're back in business.

I'd bet that my speed doubles instantly.

Then slowly they get resharpened over and over, till the bevel is round and micro beveled to death till I can't use them any more.

But Dennis, it seems that you do that on purpose, I guess that a video of you working would help to explain things,,,

I'm probably doing it all wrong.:D

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Well I don't use a Tormek, but I've got nothing against them. I've got a 1725 rpm grinder that handles any bevel regrinding.

But if I had one I'd still sharpen the cutting edge by hand. If your Tormek has a wheel coarse enough to grind a bevel quickly it won't produce a very good cutting edge unless you refine the edge by hand.

I'm not talking about deliberately rounding over cutting edges. Just avoiding flat micro bevels using jigs. Sharpening the cutting edge by hand at a slightly higher angle than the ground bevel doesn't result in that sort of edge. And using a strop or buff to take off a wire edge blurs the edge anyway, just enough to smooth the cutting action.

Flat, jig-made micro bevels on plane blades dig into the wood on contact. But planes have two handles to force the blade through the wood.

I watched someone recently "carving" a violin top plate with a blunt gouge. Enough said.

 

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3 hours ago, Dennis J said:

Well I don't use a Tormek, but I've got nothing against them. I've got a 1725 rpm grinder that handles any bevel regrinding.

But if I had one I'd still sharpen the cutting edge by hand. If your Tormek has a wheel coarse enough to grind a bevel quickly it won't produce a very good cutting edge unless you refine the edge by hand.

I'm not talking about deliberately rounding over cutting edges. Just avoiding flat micro bevels using jigs. Sharpening the cutting edge by hand at a slightly higher angle than the ground bevel doesn't result in that sort of edge. And using a strop or buff to take off a wire edge blurs the edge anyway, just enough to smooth the cutting action.

Flat, jig-made micro bevels on plane blades dig into the wood on contact. But planes have two handles to force the blade through the wood.

I watched someone recently "carving" a violin top plate with a blunt gouge. Enough said.

 

Dennis,

 I would like to see a video showing us how you sharpen.

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4 hours ago, violins88 said:

Dennis,

 I would like to see a video showing us how you sharpen.

It would probably be a major production John. I remember the first time I tried sharpening gouges and the results were not very encouraging. It took me a long time to perfect a method that worked and I've posted how I go about it.

The knives I've made recently are another challenge. I've been able to bevel these at an angle of about 15 deg. by hand using a tool rest on my grinder and water stones, but it's not easy. I think a Tormek might be the only way to go.

As a matter of interest, what angle do you grind your blades at?

 

 

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I sharpen and shape carefully and flat.  Then I have strop routine.  Does that round or bevel the final edge?

Then as needed a resharpen not so carefully.  I make sure each stage I use in resharpening goes fully to the edge.  But I use as few stages as I can get away with. And each time I use the strop.  I think these resharpenings probably do bevel the edge some.

When it does fell right anymore, then I flatten again. Etc.

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18 hours ago, Dennis J said:

It would probably be a major production John. I remember the first time I tried sharpening gouges and the results were not very encouraging. It took me a long time to perfect a method that worked and I've posted how I go about it.

The knives I've made recently are another challenge. I've been able to bevel these at an angle of about 15 deg. by hand using a tool rest on my grinder and water stones, but it's not easy. I think a Tormek might be the only way to go.

As a matter of interest, what angle do you grind your blades at?

 

 

Main grind 25 degrees. Edge angle 30 degrees..

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8 hours ago, David Beard said:

I sharpen and shape carefully and flat.  Then I have strop routine.  Does that round or bevel the final edge?

Then as needed a resharpen not so carefully.  I make sure each stage I use in resharpening goes fully to the edge.  But I use as few stages as I can get away with. And each time I use the strop.  I think these resharpenings probably do bevel the edge some.

When it does fell right anymore, then I flatten again. Etc.

I would expect the strop to cause some rounding of the bevel near the edge due to the give of the leather. I only strop my gouges which all have rounded bevels anyway.

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On 6/14/2021 at 11:36 PM, Evan Smith said:

Still not feeling it.

Eventually my gouges get rounded from sharpening.

Then when I start feeling like a drunk, wobbling around,,nibbling and digging at things,,  messing things up,, and getting impatient just farting around, digging at the wood without any control whatsoever, and after I've grabbed every last gouge and they all are shot,, nothing left but rounded micro bevel upon rounded micro bevel worn out useless garbage I quit!!

They are as sharp as a razor guaranteed,, just worthless to me.

There is nothing left to register the cut,,,you know,, register the blade to the work piece. 

It all just becomes guess work from that point,, shooting in the dark in a blinding sandstorm.

Then,,, I get out the tormac and give them a nice hollow ground edge and man does that work great, I get with the program,  with a lot of delicate and precise control, huge shavings, it is suddenly fun again. I can work fast, I quit ruining things, and BANG! we're back in business.

I'd bet that my speed doubles instantly.

Then slowly they get resharpened over and over, till the bevel is round and micro beveled to death till I can't use them any more.

But Dennis, it seems that you do that on purpose, I guess that a video of you working would help to explain things,,,

I'm probably doing it all wrong.:D

This is where I've landed, so I appreciate the validation from another member that what I'm experiencing isn't some sort of luthier-nervosa resulting from an inability to control razor-sharp dubbed gouges with rounded bevels.

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4 hours ago, Urban Luthier said:

This is where I've landed, so I appreciate the validation from another member that what I'm experiencing isn't some sort of luthier-nervosa resulting from an inability to control razor-hard dubbed gouges with rounded bevels.

You!,,Suffering from luther-nervosa,, I doubt that,,, maybe a bit sketchy at times,,,:D

I think it is from a lack of understanding about the potential that tools can have.

If one was handed a set of properly prepared and sharpened tools and demonstrated how to use them, and they got a feel for what they will do, and how precise and predictable they can work,,,then they were  handed then their old microbeveled stuff back???   

Things would become obvious. Well, maybe?

With the edge beveled or rounded the tool wants to guide itself through the wood, there is a security blanket, a safety net. The tool has a mind of it's own, and there is a fight, trying to constantly find that proper tool angle to cut where you want. To me a tool with a rounded edge is akin to nibbling all the time,, drives me bonkers.

Tools without rounding of microbevels have a straight surface like a plane bed.

(The flat side of a tool is like a plane bed used to register the tool to the work)

It becomes like using miniature planes if you will, extremely accurate,, it is easy to "feel" where and when they will cut, the tool doesn't have a mind of it's own, you do the controlling of it. It is dangerous, it is risky, the tool is not always trying to pull out of the wood and save you. You are in control. It is fun, you can work fast and accurate, if you blow it,,,, sorry, pull up your shorts and learn from the mistake.

As the microbevel gets larger and rounder,  It becomes increasingly difficult to get the tool to do exactly what you want it to. We all know that it is going to pop up out of the wood and save us from disaster, so we nibble on.

So now it is time to reface and flatten. I'm not about to re flatten every time I sharpen, in the middle of a scroll, or channel,,, no time for that. That is what micro bevels are all about, how to resharpen in between the big maintenance sessions,,, they just grow every time you resharpen, then when you can't stand it any more, fix the tool and start again.

But then again,, one could microbevel the backside and leave the working face flat, might get more mileage out of it, what a concept. I won't even strop the flat side, that edge will mirror polish out flat, just leave it alone, strop the "other" side.

So I don't understand the idea of starting out with what I call a well worn super sharp tool.

Urban Luthier,,,

Did I get it right?

 

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I think the term micro bevel is misleading. If a chisel or a knife blade is hollow ground with a jig or a Tormek at a certain angle it can be sharpened by hand at the same or slightly higher angle with very fine stones. The small bevel produced will not be perfectly flat, especially after stropping. And that to me is the best general purpose edge to have.

Regular light regrinding of the main bevel just makes it easier to sharpen with finer stones.

Gouges should not have any sort of rounding at the cutting edge apart from what might result from stropping. Rounding over the edge will mean that the cutting angle of the gouge will have to be raised too high. A gouge should cut or register with the work at a reasonably shallow angle. But the profile of the bevel should be slightly curved so that the gouge will initially dig in to the work and then come out of the cut automatically.

So essentially a gouge bevel should be continuous from edge to heel. Light, hollow grinding when resharpening will help maintain the original angle when resharpening. I think gouges need to be ground at not more than 20 degrees. Curving or doming  that surface will result in a cutting angle a little over that.

Hollow grinding plane blades and sharpening with a jig-produced micro bevel down to about 5000 grit is perfectly fine.

The bottom line is that how the tool is ground and sharpened can have a big effect on how it performs.

 

 

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On 6/12/2021 at 8:18 AM, Jim Bress said:

 some folks use...........apple seed shaped bevels. 

Niku.  Strengthens the edge for cleaving.

On 6/12/2021 at 7:39 AM, xraymymind said:

micro-bevel

Setaba awase.   Barely visible, it allows you to sharpen the edge without disturbing or defacing the main bevel.  

There's not all that much new in performance sharpening. Even Tormeks have water-driven ancestors.  :)

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16 hours ago, Evan Smith said:

(The flat side of a tool is like a plane bed used to register the tool to the work)

But flat plane bed will only allow to cut in straight line, no concave shapes.

If wee look into high level engraving where they want to change direction of cut smoothly in all directions, bevels (and not just micro bevels) are all the rage. The bevel allows cleaner cutting of curved shapes without the rest of cutter disturb (compress) the freshly cut edge.

Cutting concave parts of f hole can be easier with slightly beveled edge (or even multiple beveled).

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