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Thread: Edge Restoration - Heavy Bevel setting

  1. #21
    Senior Member blabbermouth
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    Yup, all of them.

    Diamonds cut aggressively and leaves a deep groove/stria in the beve, the larger the diamond, the deeper the cut. At the edge the bevel ends in a void or at least weakened steel, a micro-chip, you can feel it on your face as a Harsh edge. Think of a comb and the edge of a comb, exaggerated but a good example.

    Steel has a memory and once molecularly crushed by the deep groove, at the thinnest point the steel will be weakened and when thinned further, e.g. a finish stone, it will be prone to chipping.

    You can take a perfectly good shave ready edge and strop on 1um or.50 diamond, look at the edge and you will see the same thing, especially when stropped with pressure.

    Even if you do not see chipping, once the edge gets straight, 8K it can chip after a finish stone or later with just regular stropping and the edge is further thinned.

    Enough of the steel, the depth of the groove will need to be remove, a lite bread knifing or 2-3 regular honings will do it.

  2. #22
    Senior Member blabbermouth bluesman7's Avatar
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    Quote Originally Posted by Euclid440 View Post
    the larger the diamond, the deeper the cut.


    Steel has a memory and once molecularly crushed by the deep groove, at the thinnest point the steel will be weakened and when thinned further, e.g. a finish stone, it will be prone to chipping.
    Thanks Euclid.

    The first statement is the thing that is non intuitively refuted with SEM images at "The science of sharp".
    Not saying that your statement is wrong, until yesterday I would have agreed totally with this obvious fact, but there is interesting evidence to the contrary. The blogger finds this evidence surprising and perplexing also. This is all really a separate issue and not pertinent to our discussion though.

    The "molecularly crushed by the deep groove" doesn't sit well with me. Again, I'm not saying that you are wrong, but "molecularly crushed" sounds like latice distortion/ work hardening to me and I have scale issue troubles connecting this with "chips" that I can see at 100x. I've seen an awful lot of large scale fatigue failure in my career as a welder and what I'm seeing in the scope doesn't look the same to me. I would like to talk to a materials science expert about this. My brother, who is a practicing metallurgist is visiting this week. I plan on putting some razors under the scope with him. I don't know if he will be able to add anything to my understanding, but sometimes thinking about how to ask the questions leads to understanding.

    Edit; I just wanted to make it clear that I know that "doesn't sit well with me" carries zero weight as having anything to do with facts. X strokes didn't sit well with me either until the light went on.
    Last edited by bluesman7; 06-17-2015 at 04:28 PM.

  3. #23
    Senior Member blabbermouth
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    So and metal, steel that is impact damaged, is never the same. As an example a body worked fender can be made smooth, on the finish side but looking at the other side the damage is clearly visible.

    With a razor edge it is the thinness of the edge where it fails. It probably is a form of work hardening that makes it brittle and weak.
    I use to raise serial numbers from firearms where numbers were ground off.

    A stamped serial number is pretty deep, say 1/16 in, then the alter ground it a 32nd to a 16th beneath the bottom of the stamp. We would file the area smooth removing another 32nd to 16th and hit it with acid. The number would flash and remain clearly visible until the acid began to evaporate. Generally it could be repeated a couple more times.

    So the damage goes pretty deep, possibly an 1/8 to a 1/4 of an inch or more.

    Try bevel setting a razor on a 300 grit Diamond plate and then try to put an edge on it. For most, you will have to remove a bit of the edge, to get it to hold, often the edge will look ok at the low grits, but fall apart at the higher finish grits, micro chipping, when the edge is at its thinnest.

  4. #24
    Senior Member blabbermouth bluesman7's Avatar
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    Quote Originally Posted by Euclid440 View Post
    So and metal, steel that is impact damaged, is never the same. As an example a body worked fender can be made smooth, on the finish side but looking at the other side the damage is clearly visible.

    With a razor edge it is the thinness of the edge where it fails. It probably is a form of work hardening that makes it brittle and weak.
    I use to raise serial numbers from firearms where numbers were ground off.

    A stamped serial number is pretty deep, say 1/16 in, then the alter ground it a 32nd to a 16th beneath the bottom of the stamp. We would file the area smooth removing another 32nd to 16th and hit it with acid. The number would flash and remain clearly visible until the acid began to evaporate. Generally it could be repeated a couple more times.

    So the damage goes pretty deep, possibly an 1/8 to a 1/4 of an inch or more.

    Try bevel setting a razor on a 300 grit Diamond plate and then try to put an edge on it. For most, you will have to remove a bit of the edge, to get it to hold, often the edge will look ok at the low grits, but fall apart at the higher finish grits, micro chipping, when the edge is at its thinnest.
    Your talking about brinelling hardened steel past yield like what happens with the stamping. This takes pressure in the range of 100ksi. The thinner the edge is the more difficult it would be to accomplish this kind of yield, defined as permanent deformation, as the edge will simply deflect away.

    My experience using low grit diamond plates is limited to the first bevel set on newly forged razors. On a newly forged razor there are other issues that require the removal of a fair amount of the edge anyway, decarburization, gouges from low grit grinding belts etc. So it would be hard for me to ascribe damage to being the result of the diamond plate use.

    I will try it though with a razor that shows no problems to see if I can create the problems we are talking about. I think if there is damage it will be from deep scratching and not from work hardening. If this is the case, an individual notch will be gone when it's gone. If the steel is chippy from work hardening, I would expect the chip to reoccur on the same stria of hardening without physical evidence of a scratch being visible on the bevel. Maybe I can do this with Glen at the Denver meet.


    Edit: Please don't take any of this as a challenge to you or Glen. I am questioning it because I want to learn. I am perfectly happy to fail at the meet in front of everyone there if it increases my learning.
    Last edited by bluesman7; 06-17-2015 at 02:59 PM.

  5. #25
    Senior Member blabbermouth
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    I would think the thinner the steel, the easier it would be to cause subsurface damage. And even once the stria is removed, honed to the bottom of the groove, chipping will still occur, so it’s not just the groove or the edge.

    I have also seen this on new razors where guys are using newer harder steels. I suspect use very abrasive belts and possibly pressure, to form the edge, will cause chipping at finish. If the razor is honed several times or lightly bread knifed and honed, it will hold an edge.

    It does not have to be just diamond, low grit stones with too much pressure will also cause chipping. The actual cause, I don’t know, Diamonds are just more common now and new guys seem to be in more of a hurry to hone, so we see it more.

    Now, I do use diamond plates for repair work to hog of material and begin a new bevel, but leave a thickish edge where the bevels do not meet, then bring the bevels together with a 1k stone without issue. I have also had good luck with a 1k diamond plate with lite pressure for setting bevels without chipping, but normally use a 1k stone to set the bevel.

    I suspect it is a combination of aggressive large grit and pressure.

  6. #26
    Senior Member blabbermouth bluesman7's Avatar
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    OK, so I agree that a deep stria from low grit anything will result in a notch on the edge (can we call this kind of notch something other than a chip, because chip, to me, means it fractured) . I'm questioning this sub surface, work hardening damage idea, where if a notch occurred, it would indeed be a chip because it would be caused by the breaking of a brittle area in the edge.

    I was rewriting some of the last paragraph in my previous post while you posted so it may read differently to what you had read.

  7. #27
    Senior Member blabbermouth bluesman7's Avatar
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    The more I think about this subject and how to test for it, the more I realize why there is no consensus on what is actually occurring.

    I will have my metallurgist brother read this exchange when he is here over the weekend and see if he has any input. I'm not sure he has done much with abrasive wear though.
    Last edited by bluesman7; 06-17-2015 at 04:02 PM.

  8. #28
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    It is an easy problem to replicate, just set a bevel on a 325 DMT with pressure then hone it, see if it chips at the finisher.

    As to why, exactly… don’t know, were all guessing. Do know the fix, though.

  9. #29
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    I think I see why I'm not having these chipping issues. I tend to be somewhat light handed and I was not really noticing all of the posts saying "pressure". Even setting a first bevel on a newly forged razor I tend to stay pretty light.

  10. #30
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    Being a knife guy for so long has been a bad thing when it comes to razor honing, dang if I don't over pressure anytime I'm not in full concentration, a couple of Old Razors end up with chipping no matter what I do, heck, they can chip out stropping too heavy on the hanging unit.
    More time, more muscle memory, more solid concentration, all things I have to work on to avoid micro chipping.

    I'm having fun though Lynn.

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