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Thread: More sharpening (some specific questions)

  1. #31
    I am happy with the following for speed, lack of mess and relative expense:
    1) Grinder with frillable wheels and nice platform like the Wolverine jig. I have the woodcraft 8". I use it for both turning tools and chisel's/panes. I would prefer a separate 6" grinder to give more of a hollow grind for chisels etc but that will have to wait.
    2) Medium Sypderco ceramic stone: I use this to remove light nicks and to flatten the backs of irons. I also sometimes use 100 grit sandpaper on MDF clamped to my jointer for flattening the backs of irons.
    3) Fine Sypderco ceramic stone (the bigger one): I use this for honing.

    I have a Veritas MkII honing jig but I rarely use it. The hollow grind makes it pretty easy to free hand hone. And very often I can go from the wheel straight to the Spyderco fine stone with nothing in between.

    I started out with sandpaper on granite using a jig. This works but was painfully slow. I have no desire to go back to a flat bevel. It is just too much metal to work.

    From there I went to Oil Stones to move away from the sandpaper and to learn to free hand sharpen. At first they seemed to cut pretty well but after a while they became too slow. But this experience did teach me that not all of my tools need to be atom splitting sharp and it is a waste of time to try. It is better to have all your tools pretty sharp all the time then to have a couple that are amazingly sharp sometimes.

    Eventually I started turning and picked up a grinder for lathe tools. I tried it out on my plane irons and chisels and then all of a sudden sharpening was much, much easier. Having a hollow grind is great!

    Finally I added the Sypderco stones. They cut fast, haven't clogged/slowed down on me yet and they are not messy.

    Good luck with your quest but don't rule out a grinder!
    Salem
    Last edited by Salem Ganzhorn; 05-13-2011 at 12:41 AM.

  2. #32
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    I wonder if this is the paragraph George was referring to in his post…

    Diamond is unaffected by almost every other chemical or compound in nature. One exception is hot iron. The carbon atoms in diamond will dissolve into the iron, quickly eroding the diamond surface. Iron wheels are used for polishing natural diamond.
    http://www.sp3inc.com/FAQ.htm

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

  3. #33
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    Invariably,it seems, when someone mentions the laws of physics,they do not understand these laws well enough. Jim's article above mentions diamonds dissolving into hot iron. With the tiny bearing points that the diamonds on a FAST rotating wheel have upon iron,it would be perfectly feasible for localized heat from friction to be generated against the microscopic diamond contact points and the steel,and cause carbon migration. apparently SP3 has observed the migration of carbon through microscopic examination of control samples. You can even see individual atoms with an electron microscope.

    When tapping steel with a hand tap,sometimes a popping sound and sticking when trying to reverse the tap is noticed. This is a common experience to anyone who has tapped threads in steel. What has happened is the tiny cutting contact points on the tap have pressure welded to the steel. I have even had trouble convincing blacksmiths that this is what happens,but it is well known to professional machinists who have scientific knowledge of their work,and not just home brewed ideas. The gunsmiths in Williamsburg always have trouble with iron pressure welding to their rifling cutter,which has a single tooth. They know pressure welding very well. These phenomena illustrate the incredible pressure and heat that can be generated upon tiny areas of contact,even at hand tool speeds. Gentleness is the needed rule. Gentleness and slow speed are the factors to success.

    I have a friend at NASA who is now specializing in welding sheets of metal by friction of a rotating rod of steel. There are some advantages to the technique that they are investigating.

    I have already mentioned that gentle pressure only should be applied to a diamond stone. This is both to avoid dislodging the diamonds,and to prevent migration. This is why MY stones have not worn right out,not even stones from the 1970's.

    Experienced(experienced is the word here) machinists all agree that even HSS should never be ground on a fast wheel. Regardless of other additives,HSS still has an IRON MATRIX.

    I have been machining since 1959,and reading studying,and conversing with professional machinists regularly since. Professional machinists on The Practical Machinist's Forum have discussed this issue to great length. They agree that carbon migration is a fact. Do you follow this group? I do not know how long you have been machining,or what the extent of your experience is.
    Last edited by george wilson; 05-13-2011 at 9:10 AM.

  4. #34
    Think about it, Jim. One of the challenges of heat treating in a normal atmosphere is keeping the carbon in the steel when one reaches critical temperature. Even the carbon in the steel wants to migrate to the surface and oxidize. Are the carbon atoms in a diamond different in some way to where they want to ignore the tendency to oxidize and go the opposite direction and into the steel? Carbon fuels most of this planet and diamonds are just another form of carbon fuel. Get 'em hot and they oxidize, just like any other carbon.

  5. #35
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    Since you seem to just ignore what I have written,I think I will stop debating with you,Larry. You are already convinced that you have encompassed all knowledge about machining,so I wish you well. Keep on making your nice planes. The woodworking community needs them.
    Last edited by george wilson; 05-13-2011 at 9:37 AM.

  6. #36
    The correct answer is that nobody is sure exactly what the mechanism is, and it's still an active area of study. If someone wants to spend a little money, you can look up some current research on the subject, like here for instance:

    http://www.informaworld.com/smpp/con...79~frm=abslink

    My understanding is that there is more than one mechanism that results in diamond wearing on iron, but it's also my understanding that as George says, diamond tools chemically interacting with iron to form carbide is an established phenomena, though the precise mechanism is not fully understood. No need to argue this. There's a number of papers written on the subject that anyone can buy and read if they feel it's important enough.

  7. #37
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    It does me no good to encourage googling about this subject,apparently. When diamond points are in intimate contact with iron,being rubbed against it at speed and under pressure,I cannot see it as much of a leap that carbon would smear into the metal. It is only a surface phenomena,and can be seen by microscopic examination,especially by those who make and study diamond tooling. Extra carbon deposition on the surface can be seen.

    Thank you for putting that article up. I read it. Not sure if certain others may take the trouble. Personally,I am always curious,and wanting to learn. If you don't,you make no progress. There was a Master Blacksmith who just refused to learn anything that he did not stumble across on his own. For years he made plane irons that were severely dubbed over on their front faces."Every one I ever saw is like that",he said(always the same answer.) It took DECADES before he finally found some 18th.C. blades that were not
    USED TO DEATH,and then he finally began to make them correctly. Those old irons were either dubbed by the users to increase their cutting angles,or they were carelessly flipped over on the stone to wipe the burrs off after sharpening until they got dubbed. After all,they were 200 years old,and that is a long,long time to be using them.

    He refused to believe that taps got pressure welded,too. This is a very commonly known fact among those who have better educations in technology. The blacksmith's knowledge was only empirical. The gunsmith shop certainly dealt with it every time they rifled a barrel. They did not use any kind of modern,properly formulated cutting oil,which would have helped. That was their office,though,to work in the old style. They managed.
    Last edited by george wilson; 05-13-2011 at 10:14 AM.

  8. #38
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    Quote Originally Posted by george wilson View Post
    I have already mentioned that gentle pressure only should be applied to a diamond stone. This is both to avoid dislodging the diamonds,and to prevent migration. This is why MY stones have not worn right out,not even stones from the 1970's.
    George, is there an obvious way to know if you are putting too much pressure on a diamond stone?

  9. #39
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    I can't really answer that,just use enough pressure to make it cut,but don't bear down hard. It is a skill development sort of thing. Think about not dislodging the diamonds.

  10. #40
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    You can buy a 200 grit stone from Highland Hardware for about $50. This stone will take the primary bevel down very quickly. You can also use a single cut file to remove steel more quickly. That said, if you are working A2 you may need to stick with just using the stone. If you are using O1 exclusively, then the stone or file will remove metal quickly for establishing a primary bevel. I recommend the 200 grit stone, flattened via 220 grit wet/dry on a flat surface ( I use granite but that's not a requirement. ).


    A DMT xtracoarse/coarse is very valuable. I'd use the coarse to establish the primary bevel unless you have a good sized chip then the x-coarse will make short work of it. I also wouldn't worry too much about the diamond corseness leaving too deep a gouge pattern on the tool. These marks quickly come off and aren't very deep when using the coarse side of the DMT.

    The extra-fine white ceramic recommended will take care of most polishing requirements excellently. Green rouge stropping will do the rest and is really optional for most wood working requirements.

    I use water stones, which I leave in a big tupperware container soaking in water ( protected in winter ). There's no waiting for use. The higher grit stones, like the IceBear 10,000 grit just needs a quick spritz of water and about 20 seconds to soak, then it's away we go. Really puts a fine edge on a paring chisel but not required on a plane blade unless you have some very stubborn figured hardwood. Then it's worth while to give the plane blade a bit of extra edge prep.

    It's not rocket science and it only takes one thing....practice. The effort to learn will pay off bit time on the finished products reflective surface and ease of finishing.

    Enjoy the savings !

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