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Thread: Sharpening: what am I doing wrong

  1. #31
    From the first post,

    "I have a full set of diasharp diamond sharpening plates (extra-extra coarse to extra fine) and then float glass with 3M PSA lapping films from 5 microns to .3 microns."

    .3 microns is finer than froghair (I checked). The op can probably get a decent edge with what he has on hand.

  2. #32
    Beginners will sometimes just not recognize their own just made sharp edge ,so they put aside the stone they used and go for something
    that will tear open their finger Ö..maybe a cinder block hone ! Test your new edge on WOOD before just guessing if itís sharp. SadlyÖ.a
    sharp good edge usually doesnít feel like itís any good. Learn to discern ,donít hold on to your beginner judgement.

  3. #33
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    Quote Originally Posted by Kevin Jenness View Post
    From the first post,

    "I have a full set of diasharp diamond sharpening plates (extra-extra coarse to extra fine) and then float glass with 3M PSA lapping films from 5 microns to .3 microns."

    .3 microns is finer than froghair (I checked). The op can probably get a decent edge with what he has on hand.
    The issue with diamonds is that they cut really deep scratches.

    People are a bit too focused on "grit" as a measure of edge fineness. Something like an Arkansas stone for example, is only like 600 grit technically, and maybe up to 1000-2000 "grit" for the very finest transluscent / blacks. But the thing is, the height difference between the peaks and vallies are so much closer together that they leave a screaming sharp edge, despite having way fewer cutting pores than, say, a fine or extra fine DMT. With Arks you also get a slight burnishing effect in addition to subtle cutting action, and in the end, the edge you get is of a totally different nature. Other natural and synthetic stones will leave very different edges with different characteristics, too, and may be more or less suitable for different tasks / cutting different things.

    I've used diamonds and other kinds of stones extensively, and I even like diamond plates and consider them a good all around option, but Warren is right in that they will never leave a truly fine edge like many other stones can, regardless of the grit rating. The scratches they leave are just too deep.

    You can indeed confirm this by doing as Warren suggests and sharpening a razor on diamond plates. Use any diamond plate you like, but I don't think you'll get a comfortable edge like you can off of a Jnat or Arkansas stone, or even (to a less noticeable degree) a synthetic finishing stone in the same ballpark grit.
    Last edited by Luke Dupont; 10-20-2021 at 12:18 AM.

  4. #34
    Quote Originally Posted by Luke Dupont View Post
    The issue with diamonds is that they cut really deep scratches.

    People are a bit too focused on "grit" as a measure of edge fineness. Something like an Arkansas stone for example, is only like 600 grit technically, and maybe up to 1000-2000 "grit" for the very finest transluscent / blacks. But the thing is, the height difference between the peaks and vallies are so much closer together that they leave a screaming sharp edge, despite having way fewer cutting pores than, say, a fine or extra fine DMT. With Arks you also get a slight burnishing effect in addition to subtle cutting action, and in the end, the edge you get is of a totally different nature. Other natural and synthetic stones will leave very different edges with different characteristics, too, and may be more or less suitable for different tasks / cutting different things.

    I've used diamonds and other kinds of stones extensively, and I even like diamond plates and consider them a good all around option, but Warren is right in that they will never leave a truly fine edge like many other stones can, regardless of the grit rating. The scratches they leave are just too deep.

    You can indeed confirm this by doing as Warren suggests and sharpening a razor on diamond plates. Use any diamond plate you like, but I don't think you'll get a comfortable edge like you can off of a Jnat or Arkansas stone, or even (to a less noticeable degree) a synthetic finishing stone in the same ballpark grit.
    I agree that "grit" isn't particularly useful when comparing between stone types. 8000 grit diamond equals 3 microns, while 8000 grit waterstones may be half that. I don't see any reason why a 3 micron diamond plate would leave a deeper scratch than a 3 micron abrasive particle of some other mineral, unless we're assuming that the other mineral particles are fracturing upon abrasion (in which case we're not comparing apples to apples). I wonder whether there's any hard data (e.g., micrographs) comparing the finish off Arkansas stones versus diamond plates (for example), given that the finest Arkansas stones are ~6 microns (at least, Dan's are) and the finest DMT Diasharps are 3 microns. You're not the first person I've seen who prefers the finish off an Arkansas stone after diamond plates, but it seems to run in the face of the numbers, so I'm curious whether there's something subtle going on.

  5. #35
    Quote Originally Posted by Jim Koepke View Post
    There is some wisdom in the above words.
    Jim, I am rarely accused of wisdom in any quantity. Would you be so kind as to send me a dated and notarized copy of your post for use in future arguments?

  6. #36
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    Quote Originally Posted by Tyler Bancroft View Post
    I agree that "grit" isn't particularly useful when comparing between stone types. 8000 grit diamond equals 3 microns, while 8000 grit waterstones may be half that. I don't see any reason why a 3 micron diamond plate would leave a deeper scratch than a 3 micron abrasive particle of some other mineral, unless we're assuming that the other mineral particles are fracturing upon abrasion (in which case we're not comparing apples to apples). I wonder whether there's any hard data (e.g., micrographs) comparing the finish off Arkansas stones versus diamond plates (for example), given that the finest Arkansas stones are ~6 microns (at least, Dan's are) and the finest DMT Diasharps are 3 microns. You're not the first person I've seen who prefers the finish off an Arkansas stone after diamond plates, but it seems to run in the face of the numbers, so I'm curious whether there's something subtle going on.
    Is micron a measure of height variation, or width variation? Does it assume that height and width are equal when discussing "particle size"? You can have particles spread further apart with less differentiation between peaks and vallies, and you can also have particles that wear and become duller and rounder as opposed to remaining sharp and pointy. And in the case of Arks, you have particles that are so tightly fused together that you have something of a more solid surface with pores rather than extruding bumps / crystals.

    There are a ton of variables that go into it which some measure of "particle size" doesn't capture, I think. The shape of the particles, the way that they wear or don't wear (how sharp or rounded they become) and the nature of the surface (pores versus protruding particles, and how even or far apart they are spread), as well as things like friability or lack thereof (Jnats and waterstones, for example, with their abrasive particles that are suspended in a slurry).

    All these factors and many more produce different sorts of cutting actions, and impart different edges. I'd love to know, too, if anyone has a measure of all these different factors and can explain how they work.

    It's also worth noting that difference in the hardness of the stone versus the steel affect the finished edge as well. Sharpen an O1 tool on an Ark, and then Japanese steel, and then A2, and you will find different results and cutting action on each one. The O1 chisel will have a slightly coarser edge than the Japanese chisel, which because of the narrow hardness gap between the steel and the stone, will be more polished and burnished on the Arkansas stone, making a Soft Ark cut produce a finish somewhat finer and closer to a Hard Ark.

    If the difference in hardness is further apart, you will get less polishing and more grinding - you will cut quicker but coarser. Sharpen those three steel types on diamonds and you will notice very little difference in the finished edge.
    Last edited by Luke Dupont; 10-20-2021 at 1:01 AM.

  7. #37
    Quote Originally Posted by Luke Dupont View Post
    Is micron a measure of height variation, or width variation? Does it assume that height and width are equal when discussing "particle size"? You can have particles spread further apart with less differentiation between peaks and vallies, and you can also have particles that wear and become duller and rounder as opposed to remaining sharp and pointy. And in the case of Arks, you have particles that are so tightly fused together that you have something of a more solid surface with pores rather than extruding bumps / crystals.

    There are a ton of variables that go into it which some measure of "particle size" doesn't capture, I think. The shape of the particles, the way that they wear or don't wear (how sharp or rounded they become) and the nature of the surface (pores versus protruding particles, and how even or far apart they are spread), as well as things like friability or lack thereof (Jnats and waterstones, for example, with their abrasive particles that are suspended in a slurry).

    All these factors and many more produce different sorts of cutting actions, and impart different edges. I'd love to know, too, if anyone has a measure of all these different factors and can explain how they work.

    It's also worth noting that difference in the hardness of the stone versus the steel affect the finished edge as well. Sharpen an O1 tool on an Ark, and then Japanese steel, and then A2, and you will find different results and cutting action on each one. The O1 chisel will have a slightly coarser edge than the Japanese chisel, which because of the narrow hardness gap between the steel and the stone, will be more polished and burnished on the Arkansas stone, making a Soft Ark cut produce a finish somewhat finer and closer to a Hard Ark.

    If the difference in hardness is further apart, you will get less polishing and more grinding - you will cut quicker but coarser. Sharpen those three steel types on diamonds and you will notice very little difference in the finished edge.
    That's a good point. Ultimately, I think performance is the most important measure. I can get a nice glassy surface on my usual woods (maple and cherry) with planes sharpened to DMT extra-extra-fine, and that's what matters to me – obviously, different people have different standards. I have a King 8000x left over from my waterstone days that I may try using after the EEF to see if it makes a difference. (I also have some olivewood with rather wild grain that I should do some test planing on.)

    Someone out there must have some micrographs, though.

  8. #38
    The issue with diamonds is that they cut really deep scratches.


    The op is not finishing with diamond, but with (I believe) aluminum oxide on a film backer. In any case, his problem seemed to be in getting an edge that was useable, let alone "truly sharp", so the fix was in technique rather than the abrasive type.

    Those interested in pursuing the "best" sharpening technique might find this interesting https://brentbeach.ca/Sharpen/jig%20faq%2002.html

    Also this https://inthewoodshop.com/WoodworkTe...gStrategy.html
    Last edited by Kevin Jenness; 10-20-2021 at 8:36 AM.

  9. #39
    I got an email from Brent Beach in 2007 asking for my sharping regimen. I wrote seven paragraphs and sent it to him. He then told me I sharpened backwards! He thought an Arkansas stone was coarser than an 800 King water stone!! I don't think he had much experience sharpening or woodworking.

  10. #40
    Quote Originally Posted by Warren Mickley View Post
    I got an email from Brent Beach in 2007 asking for my sharping regimen. I wrote seven paragraphs and sent it to him. He then told me I sharpened backwards! He thought an Arkansas stone was coarser than an 800 King water stone!! I don't think he had much experience sharpening or woodworking.
    And I know even less than he does. Sad! It's amazing that any woodwork actually gets done considering the weakness of my sharpening regimen.

    Seriously though, I thought his remarks about deformation caused by grinding to the edge were interesting- perhaps correct- and quite contradictory to the method described here http://www.inthewoodshop.com/Woodwor...ningSetUp.html by Derek Cohen, who also said "The problem with sharpening threads on forums is that they all end up the same way - a million different methods and recommendations ... proving that everyone is wrong and I am the only one with the secret to the right way to do this!"

  11. #41
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    Didn't meant to start any arguments folks. I should have clarified my question a bit -- I am generally interested in other approaches/types of sharpening media, but particularly (as Jim notes, per his earlier comments) in the idea that the finer diamond stones are limited. Which is why I have the lapping paper. I just haven't been too impressed with the paper. And in my own defense, the diasharp plates came in a discounted set of three, but I bought the coarser stones because I knew I had some old damaged blades to restore. A piece of float glass and a sampler pack of lapping papers was very cheap. To Mel's point, I have been trying all of the blades on wood. Great results on pine and cherry. Maple is touch and go. But again, some of the issue is that I need to get better at using hand planes. The chisels I sharpened last night seem to be doing a fine job, not that I'm any kind of master with using chisels either...

    Brian, thanks for that kind offer, I will PM you separately.
    Last edited by Dan Gaylin; 10-20-2021 at 1:33 PM.

  12. #42
    If you want pictures, you should go over to wood central and David Weaver's youtube channel. He upload lots of pictures of blades after honing on various stones as do other contributors.

  13. #43
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    More important than how nice a blade's edge may look under magnification is what it does to the surface being worked.

    This image shows an indication of a blade in need of a little honing:

    Light Lines From Blade.jpg

    The light lines (follow the arrows) are caused by small nicks or wear spots on the blade's edge. The socket to the left is what it looked like after a little touch up of the blade.

    If a plane blade is cutting ribbons it likely could use a few passes on a stone.

    You might need a microscope camera to see these defects. Without such equipment your shavings or surface will let you know what you have.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  14. #44
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    Quote Originally Posted by Dan Gaylin View Post
    Didn't meant to start any arguments folks. I should have clarified my question a bit -- I am generally interested in other approaches/types of sharpening media, but particularly (as Jim notes, per his earlier comments) in the idea that the finer diamond stones are limited. Which is why I have the lapping paper. I just haven't been too impressed with the paper. And in my own defense, the diasharp plates came in a discounted set of three, but I bought the coarser stones because I knew I had some old damaged blades to restore. A piece of float glass and a sampler pack of lapping papers was very cheap. To Mel's point, I have been trying all of the blades on wood. Great results on pine and cherry. Maple is touch and go. But again, some of the issue is that I need to get better at using hand planes. The chisels I sharpened last night seem to be doing a fine job, not that I'm any kind of master with using chisels either...

    Brian, thanks for that kind offer, I will PM you separately.
    Your current equipment is not what I would prefer to use for day to day sharpening, but it is totally capable of getting the job done. I would stick with it until you can consistently get very good edges with minimal effort (say less than 5 minutes instead of 15-20). At this point introducing new equipment would just slow down your progress.

    The basic idea of sharpening is to remove any wear or damage at the very edge, and establish a new edge with correct geometry. The level of polish is much less important than getting the geometry right at the very edge. Beginners tend to get wrapped up in scratch patterns and finer and finer grits, but most of their problems are because they don't "finish the job" all the way out to the very edge, though they may have a mirror polish on the rest of the bevel.

    It sounds to me like you have a thick iron with a large bevel, and you were trying to work the whole bevel at around 25 degrees to match the factory grind. That is going to take a long time regardless of sharpening media, meaning there's a high likelihood that the very edge is not quite reached. One way or another you need to reduce the surface area being honed, and you'll find that things go much faster and the edges you get are better.

    Basically you can reduce the surface area by hollow-grinding with a wheel grinder, or by sharpening a small secondary bevel at a higher angle than the main grind. You didn't mention having a grinder, so I recommend the second approach. If the factory grind is 25 degrees, hone at 30 or even 35. Now you are working the tip only, and much less surface area, so the job gets done many times faster. Hone on a fairly coarse stone until you get a very obvious burr - this is the main indication that you "finished" the job and established a new edge.

    Eventually with more sharpenings the secondary bevel will get wider and wider and things slow down again. At this point you can get your float glass with your coarsest paper (nothing finer than 100 grit) and work the factory 25 degree bevel until the secondary bevel is very small again. (Pro-tip: change the sandpaper every few minutes of use, it cuts dramatically faster when fresh than after even a modest amount of use).

    Eventually you will probably want a grinder if you are going to work with modern, thick blades and steels like PMV11. But what I described above is feasible.

  15. #45
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    I have seen a lot of really good advice.


    Step 1: make sure that your back is flat up to the edge. You do not need the entire blade, even the lat 1/4" will do, but i usually have closer to 1".

    Now, you need to get a nice edge up to the "end" so that it is sharp. One thing that usually helps, is to use a black marker to cover the blade bevel. If you are sharpening, you can then see what you scraped off. If it does not go to the edge, well, that is why it is not sharp. If it does go to the edge, then the problem is probably a burr / wire edge.

    Often a magnifier helps here. I use an 8x or 10x loop to take a look. Doing this with knives really improved my sharpening by a big margin.

    Someone mentioned a "hollow grind". I do this, and it helps me seat the blade onto the stone AND it is faster to deal with. One draw back is that eventually I need to re-establish the hollow grind. It does help to free-hand when I want to do a touch up.

    If you really want to give that a try, ship me a blade and let me put a hollow grind on it and I will ship it back to you. Try the marker thing first to see what you are really doing.

    Andrew Pitonyak.

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