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Thread: Honing after hollow grinding

  1. #1
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    Honing after hollow grinding

    After reading posts from about 600 of the previous Neader pages (skimmed them over several months) I’m still confused about what happens when honing a chisel or plane blade after hollow grinding, be it free hand or with a jig.

    Does one just hold the hollowed metal flush to the honing stone and create a “microbevel”, albeit one exactly parallel to the original two edges of the metal as it came off the grinder, say at 25 or 30 degrees? Or do you change the angle and form a secondary angle on the already fairly small metal cutting edge?

    It seems sort of intuitive to me that if one of the reasons for using microbevels is to decrease the amount of metal being sharpened, and speeding up and easing the amount of work, this has already pretty much occurred after the hollow grinding.

    For purposes of discussion I’m using an 8” CBN wheel.

    Thanks, Jon

  2. #2
    Stop reading and get to sharpening and your confusion will be relieved. The easiest and most consistent way (without a jig) is to register the tool on the stone using the toe and heel of the hollow. You will be removing more material than if you raise the heel and make a microbevel. Some people raise the heel but then you have to rely on "feel" and practice to get the microbevel angle consistent. Try it both ways and see what works. You may find using a honing jig to achieve a microbevel works best for you.

  3. #3
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    Kevin, thanks. Just to be clear I’ve been honing for a long time, mainly freehand but also have a drawer full of jigs. The CBN wheel is a new gift. Before that I could never get happy with the various white and blue ones on my old Baldor and never used them.
    Last edited by Jon Snider; 04-24-2022 at 11:08 AM.

  4. #4
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    Hi Jon

    I freehand on the hollow, which jigs the blade, maintains the bevel angle, and keeps the face coplanar.

    Regards from Perth

    Derek

  5. #5
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    Thanks Derek. Was hoping you were up and about over there!

  6. #6
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    The really great thing about convex grinds is that you don't really need a micro-bevel.

    I don't have a grinder, so I don't typically sharpen hollow ground tools, but if I did, I'd do as Derek describes and just sharpen them flat on the stone. I have sharpened many tools that came to me with a hollow grind, however, and I certainly did appreciate it.

    Then again, I usually just sharpen with a full flat or slightly convex bevel on all of my tools, which aren't typically hollow ground. I just find it easier, as you don't have to worry about what angle your micro bevel is or go through the ordeal of grinding it back down when it gets too large. Easier to just be consistent for me.

    Some people will use a small microbevel -- a truly micro bevel, on a hollow grind, though. I recall watching a video of David W. sharpening a plane iron on a Washita and a Transluscent, and advocating putting a truly small microbevel (like one or two strokes) on the edge with the transluscent -- small enough that it comes out quickly with the next sharpening just on the Washita. This would be a good way of doing it if you want a micro bevel. But I definitely wouldn't have a large micro bevel on a hollow grind, as that would create problems and soon change the cutting angle, I imagine..

  7. #7
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    Just for clarity, I differentiate between a micro bevel and a secondary bevel. This is not the way these terms are used generally, but I find the common way to cause confusion.

    When I refer to a micro bevel, I mean a bevel that is very tiny … micro in size. Numbers? 1mm in width, or less. There is no angle implied by “micro bevel” - it may be coplanar with the bevel face.

    A secondary bevel (and a tertiary bevel) is a bevel which is at a steeper angle to the primary bevel. A secondary bevel may be created by hand. It is almost always what is created by a honing guide. There is no size to a secondary bevel, just that it is higher than the primary bevel.

    Now you can have a micro secondary bevel, and this is what may create in honing an edge when they list the blade for a few strokes at the end (see Rob Cosman and David Weaver).

    When honing directly on the face of a hollow grind, as long as the hollow reaches the edge of the bevel, you will create a micro bevel (see my earlier photos). This is not a secondary bevel as it is coplanar.

    A little to take in, hopefully not confusing, but I find it makes more sense.

    Regards from Perth

    Derek

  8. #8
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    Great description Derek. As I was taught in the Marine Corps: “Words mean things”

  9. #9
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    Quote Originally Posted by Derek Cohen View Post
    Just for clarity, I differentiate between a micro bevel and a secondary bevel. This is not the way these terms are used generally, but I find the common way to cause confusion.

    When I refer to a micro bevel, I mean a bevel that is very tiny … micro in size. Numbers? 1mm in width, or less. There is no angle implied by “micro bevel” - it may be coplanar with the bevel face.

    A secondary bevel (and a tertiary bevel) is a bevel which is at a steeper angle to the primary bevel. A secondary bevel may be created by hand. It is almost always what is created by a honing guide. There is no size to a secondary bevel, just that it is higher than the primary bevel.

    Now you can have a micro secondary bevel, and this is what may create in honing an edge when they list the blade for a few strokes at the end (see Rob Cosman and David Weaver).

    When honing directly on the face of a hollow grind, as long as the hollow reaches the edge of the bevel, you will create a micro bevel (see my earlier photos). This is not a secondary bevel as it is coplanar.

    A little to take in, hopefully not confusing, but I find it makes more sense.

    Regards from Perth

    Derek
    Good distinction! I was calling them both "micro-bevels" but I guess the term "micro-bevel" is there specifically to differentiate it from a "secondary bevel."

  10. #10
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    Quote Originally Posted by Luke Dupont View Post
    The really great thing about convex grinds is that you don't really need a micro-bevel.

    I don't have a grinder, so I don't typically sharpen hollow ground tools, but if I did, I'd do as Derek describes and just sharpen them flat on the stone. I have sharpened many tools that came to me with a hollow grind, however, and I certainly did appreciate it.

    Then again, I usually just sharpen with a full flat or slightly convex bevel on all of my tools, which aren't typically hollow ground. I just find it easier, as you don't have to worry about what angle your micro bevel is or go through the ordeal of grinding it back down when it gets too large. Easier to just be consistent for me.

    Some people will use a small microbevel -- a truly micro bevel, on a hollow grind, though. I recall watching a video of David W. sharpening a plane iron on a Washita and a Transluscent, and advocating putting a truly small microbevel (like one or two strokes) on the edge with the transluscent -- small enough that it comes out quickly with the next sharpening just on the Washita. This would be a good way of doing it if you want a micro bevel. But I definitely wouldn't have a large micro bevel on a hollow grind, as that would create problems and soon change the cutting angle, I imagine..

    Luke, I understand why you hone a rounded bevel. I am not convinced, however, that it is especially efficient. My Japanese chisels are all honed on the flat. No micro secondary bevel. This is made easier by the laminated construction, however many others (for example Warren) hone their solid blades on the flat.

    The rounded bevel method has been popularised by Paul Sellers. I think that he advocates this as it does not rely on a grinder, and may be done freehand. It is a useful method to have under your belt - knowing many methods adds to your arsenal - and, indeed, I use it for Western mortice chisels (which use a 25 degree primary bevel - my Japanese mortise chisels are flat-honed at 32 degrees).

    A question came up on another forum very recently about PS' methodology. This is what I wrote ...

    I find it revealing that Paul Sellers uses 300/600/1000 grit diamond stones. This suggests that his sharpening method is inefficient. By contrast, many (myself included) begin their sharpening sequence from 1000 grit. Paul does not end with 1000 grit, and neither does anyone else, but this is not relevant here.

    The reason he begins with 300 grit is because he has to remove more steel. The long, curved bevel face has far more steel to remove than honing a micro bevel (in the case of freehanding on the face if a hollow grind). or honing a secondary micro bevel (in the case of a honing guide). In the method I prefer - honing on a hollow - the amount of steel to remove is minuscule, and it is possible to even forgo the 1000 grit.

    Regards from Perth

    Derek

  11. #11
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    Quote Originally Posted by Derek Cohen View Post
    Luke, I understand why you hone a rounded bevel. I am not convinced, however, that it is especially efficient. My Japanese chisels are all honed on the flat. No micro secondary bevel. This is made easier by the laminated construction, however many others (for example Warren) hone their solid blades on the flat.

    The rounded bevel method has been popularised by Paul Sellers. I think that he advocates this as it does not rely on a grinder, and may be done freehand. It is a useful method to have under your belt - knowing many methods adds to your arsenal - and, indeed, I use it for Western mortice chisels (which use a 25 degree primary bevel - my Japanese mortise chisels are flat-honed at 32 degrees).

    A question came up on another forum very recently about PS' methodology. This is what I wrote ...

    I find it revealing that Paul Sellers uses 300/600/1000 grit diamond stones. This suggests that his sharpening method is inefficient. By contrast, many (myself included) begin their sharpening sequence from 1000 grit. Paul does not end with 1000 grit, and neither does anyone else, but this is not relevant here.

    The reason he begins with 300 grit is because he has to remove more steel. The long, curved bevel face has far more steel to remove than honing a micro bevel (in the case of freehanding on the face if a hollow grind). or honing a secondary micro bevel (in the case of a honing guide). In the method I prefer - honing on a hollow - the amount of steel to remove is minuscule, and it is possible to even forgo the 1000 grit.

    Regards from Perth

    Derek
    Paul Seller's method is good for thin plane irons if sharpening free hand. I don't care to try to keep a 1/8" iron perfectly flat on the stone with such a registration surface, nor does it matter!
    Another advantage is that it does allow a better cutting action on certain natural stones, particularly Arks, as less of the bevel is in contact with the stone at any one time. A large surface area on an Ark can often lead to the bevel "sliding on" the stone and a reduced cutting action. This is probably for similar reasons that short strokes, and small circular strokes are advantageous on Arks, as opposed to the typical continuous, full strokes that most people employ.

    I don't really use Paul Seller's method as he shows, though. The curvature is barely noticeable on my tools by comparison. It's maybe 1-2 degrees of variation, if that. I do that in part to avoid "stiction", which I discuss below with regard to Japanese tools.
    My method is far from the most efficient, I'm sure, but I rarely go any finer than a Soft Arkansas or Washita unless a blade is damaged or really worn down.

    For Japanese tools, I keep an almost perfectly flat bevel, but I allow an imperceptible amount of rounding to occur at the top to avoid "stiction", as it's a real drag when your perfectly flat plane iron bevel suddenly sticks to the stone just as you're pushing forward, causing you to nose dive into the stone and create a micro/"macro" bevel that you then have to take out again, only to keep having the same frustrating experience occur. Not many people seem to talk about this, but it happens every single time I make the bevel perfectly flat. So, I can only guess that most people allow a tiny amount of rounding to occur, otherwise they'd almost certainly stumble into the same problem unless skewing the blade at a pretty significant angle.

    But for Western chisels, or thick Western plane irons, I'd love to try the hollow ground approach one day. I can definitely see how it would make the sharpening process extremely efficient. I just can't justify owning a grinder currently. One day, when I have more space, and money!

    I think Paul Sellers does a lot of what he does because it's accessible, and beginner friendly. Not everyone can own a grinder. And for beginners, it's far easier to return often to a coarse stone to remove chips and fix geometry (which, if you're not good at sharpening yet, you will mess up quite a bit). I speak from experience on the latter point, as when I was a beginner, I started with a #1000 grit waterstone, which turned out to be much too fine to address the work that needed to be done on factory ground tools. Of course, I didn't know that at the time, and wondered why my tool just never got sharp no matter how much I ground. It just wasn't coarse enough to get down to the edge. Then you start lifting up to get to the edge, and go a little too far. And then you *really* need a coarse stone or a grinder. Better to just start beginners off with the coarsest, flattest stone available, hence Paul's Diamond stone set up, I think.
    Last edited by Luke Dupont; 04-25-2022 at 9:28 AM.

  12. #12
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    I use a hollow grind because:


    1. It is what I own to sharpen; I own a Tormek so it will leave a hollow grind.
    2. I have fast success because I simply register the "hollow" and go.


    The hard work is done creating the hollow. After that, I can use a much higher stone. I usually start around 5K or 6K on the back then the hollow. I then jump directly to my 16K and do the same.

    I do not use a guide at this point; it is easier to register against the hollow for me.

  13. #13
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    You can hone on the grind for straight/very close to straight cutters, but it's easier IMO to do a little tip up on profiled cutters like your jack plane in order to maintain the shape at the end. I don't doubt that others have mastered doing so by honing on the grind though.

    If you tip up over the grinding angle then your bench grinder can stay set at one angle, and any little adjustments you want to do to a particular cutter, with regard to angle, is done at the honing stone by tipping a little more or a little less, or perhaps none for a bench chisel for instance.

    25* grinder (or even a little less) - change the ultimate angle at the honing stone.
    Last edited by Charles Guest; 04-25-2022 at 2:41 PM.

  14. #14
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    I'm late to this but will add that hollow grinding allows easy side sharpening and honing of plane irons. Side sharpening is my preferred method as there is no loss of reference.

  15. #15
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    Quote Originally Posted by Bruce Mack View Post
    I'm late to this but will add that hollow grinding allows easy side sharpening and honing of plane irons. Side sharpening is my preferred method as there is no loss of reference.
    Are you referring to sharpening with the blade 90 degrees to the stone and moving the blade side to side? I like that method as well for plane blades.

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