CBN grinding wheels?

Discussion in 'Woodturning Discussion Forum' started by bob sesti, Apr 28, 2012.

  1. john lucas

    john lucas

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    Well considering David turns mostly spalted wood that I'm sure has problems, and has for more years than most of us have been turning I would take his opinion. Besides he's just a plain nice guy and certainly doesn't act like a god.
    My first every demo at the AAW symposium was on Photography. The first person to walk in the room was David Ellsworth. To say I was nervous would be an understatement. The video equipment was not working properly and I had not seen that equipment before. David very nicely came up and helped to get it all working. He will stop and talk to any turner just like you and I would chat.
    There still are disputes among even the top turners as to whether you need to hone. If you look at the results Stewart Batty and Jimmy Clewes get right off the grinder it's awfully hard to believe. Some feel the saw tooth edge actually cuts green wood better.
     
  2. Bill Boehme

    Bill Boehme Administrator Staff Member

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    From my experience, I have no doubt that the rougher edge cuts green and dry wood more easily -- perhaps not quite as smoothly, but not much of a difference. I have an unverified hypothesis that a more refined edge lasts longer, but I am not really interested in verifying that hunch since I go both ways when sharpening.
     
  3. Brian McInturff

    Brian McInturff

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    So someone other than Odie explain to
    me the "big" benefit to honing for anything other than a finish cut, or on a really, really difficult wood. Seems the objection is to remove wood and get the general shape. Then you hone for the finish cut. Obviously I've touched up an edge just so I don't have to go resharpen but that's when I feel it getting a little dull and don't want to stop the lathe. Do you hone after each and every sharpening? I'm trying to understand the logic but my analytical way of thinking tells me it's not needed if the tool is sharpened correctly and used correctly.

    Now a question for Odie: wouldn't a 180 grit wheel be better than an 80 grit wheel for honing?
    An 80 grit leaves a pretty jagged edge when you look at it magnified as compared to a 180 grit. So the honing process is less on a 180 as opposed to an 80. As for the CBN wheels a sharpened 180 looks a lot closer to a 600 under magnification than it does a 120. That could be because the wheels are so true and uniform when compared to a friable wheel. The CBN's when properly installed run truer than any friable/matrix wheel I've seen, in any shop.
     
  4. Matt Lewis

    Matt Lewis

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    I may have misunderstood, but you can not compare CBN grits to friable in a one to one manner. A 180 in CBN terms is close to an 80 grit in friable terms and an 80 grit in CBN is close to 46 in friable.....two different identification standards. Sorry to interrupt the conversation, but just wanted to ensure apples are being compared to apples.

    Best regards,

    Matt
     
  5. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Brian, there was an article in AW by Alan Lacer one or two years ago and I believe the conclusion was that a honed edge is usable for a longer interval between sharpenings.
     
  6. odie

    odie

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    Thanks for this, Steve......

    It doesn't surprise me that David Ellsworth took a concept that was already being experimented with and modified it. That was innovation at work.....and, a bit of "vision"!

    ooc
     
  7. odie

    odie

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    Al......

    That would be a question subjective in scope. I believe if you took a poll of knowledgeable turners, David Ellsworth would be among the top of that list.......and, that's where I'd put him.

    ooc
     
  8. odie

    odie

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    I believe I've made a few mistakes in this thread......

    First of all, is to assume the point would not be completely lost, and irretrievable on so many here. My assumption was incorrect the average age of those on this forum meant there would be a higher level of wisdom in seeing that point. I failed to see the degree of hero-worship, sainthood, adoration, etc., there is.....and, it's probably deeper than I thought! This is human nature I suppose, and we all do need our heroes. I have my own heroes, too! In the world of woodturning, David Ellsworth is a very good choice IF someone needed a hero that can do no wrong.......for the rest of us, including me, he is someone to admire and learn what I can, from what he has to offer......but, his place is somewhere less than sainthood status in everything he does. I'm sure Ellsworth realizes this about himself, but there are those who put him far above how he sees himself......and THAT is the point.

    Another mistake I've made is to not make the point absolutely clear, and therefore avoiding those who thought I was attacking David Ellsworth himself. I was attacking the "larger than life" status he has among some (many) turners.....and, not him personally.

    ooc
     
  9. hockenbery

    hockenbery AAW Advisor Staff Member

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    Odie,

    do not confuse admiration and respect with deification and beatification.

    I have a deep respect and admiration for David.

    Al
     
  10. MichaelMouse

    MichaelMouse

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    You shave with the blade broadside to the whiskers, right? Don't pull that blade longwise on your flesh. Hopefully, you only go broadside into the wood when you absolutely MUST while turning. The edge analogy I suggest is a comb. When you look at it wide, it's pretty ragged looking. The standard pocket comb usually even has two spacings (grits) to reinforce the point. Now sight along the edge. Not only can you not see where the coarse and wide are, it looks sharp, too. Presentation trumps grit,as I see it.

    Couple thoughts. The edge goes bad because it rolls its own burr, not because it chips out. Change analogies to a saw, where the teeth have set in them. Only you don't hammer them out, you abrade them away. That's why honing, where the steel is amenable and the damage caused by something besides sand in the bark (guilty!) works to make a good edge again. Or turning a new one with your burnisher, where the metal is malleable enough.

    Or, the edge goes bad because it is rounded by extremely fine abrasive in the wood itself. The kind that makes your 600 stone look like a 60. A few passes with that heavy 600 grit makes a chamfer out of a roundover, and off we go again.

    I personally don't know whether Ellsworth knows more about metal and edges than Doug Thompson, Ron Hock, or even Charlie Potatoes down the block. But I do know that the Halo effect can be misleading. http://www.wisegeek.com/what-are-halo-effects.htm
     
  11. Gretch Flo

    Gretch Flo

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    interrupting to sharpen

     
  12. Thomas Stegall

    Thomas Stegall

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    To hone or not to hone?

    At the 25th AAW symposium I had the privaledge to do video for the demos including Dale Nish's demo on turning a bowl from green wood. One of the attendees asked about Dale's view on the value of honing turning tools. His response was to say that it has great value in woodworking hand tools like a traditional chisel. However, since the average turning tool will cut more wood in an hour of turning than a chisel will likely cut in an entire lifetime, he did not see the value in honing after each sharpening. He estimated that on american hardwoods the honing sharpness probably had a life of 5 seconds during stock removal. (I would imagine that duration would depend on which turning tool and what type of cut was being done, but his point was well made).

    He went on to say that he had asked Richard Raffan if it was possible to produce a noticably better surface on wood with a honed tool. Richard said "absolutely". Dale then asked "So do you hone your tools?", Richard replied "No" Dale asked "Well why not" Richard said "Because I am a woodturner, not a tool sharper, its a waste of time, unless you plan to only turn for five seconds."

    By the way in, the course of this discussion I think two things have gotten confused at least by some participants. 1) Honing a scraper and burnishing a scraper are two very different processes with two different results. 2) (Regardless of our opinion of David) Odie's critcism of individuals who in his terms "worship" David, is not the same as being critical of David himself. His words could have been better chosen as he has acknowledged, but it seems the intent of his comments was directed at "hero worshipers", not the hero (David) himself.

    While you may see things very differently from Odie, the element of hero worship or the "halo effect" that he was attempting to address, is alive and well within the AAW. And its certainly not limited to the admiration of David. Since our club has been able to bring in world class demonstrators for club demos I see it all the time, even among my friends. Sixty year old men anxiously waiting for an autograph and conversation from a demonstrator not all too differently than when they were teenagers at a rock concert.

    Binh was just telling me last week that another friend we have in common has coined a term he calls the "Binh Effect" because our friend often gives Binh some cash to make a purchase for our friend's collection when Binh travels to various symposia. The "effect" is that when Binh attempts to make this proxy purchase for our friend, the artist who five minutes ago was asking $1200 for a piece, refuses to let Binh pay for it at all once Binh has expressed an interest in buying the piece. They assume Binh is buying it for his own collection and they refuse payment for it. Binh then has to explain that it is a proxy purchase in order to get them to accept payment for the piece. I'm sure this "effect" is not unique to Binh, and is evidence of our tendency towards hero worship.
     
    Last edited: May 1, 2012
  13. KellyDunn

    KellyDunn

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    Thomas, almost made me laugh. When I go to major events I get a bit of the hero thing. Since I dont teach as much as I used to it takes me by suprise as I am not used to it. They find out real quick I am human. But I am active in our local club. Not only no hero worship But when discussions of bringing in demo folks with certain talents come up and I say we the talent right in this room. And Its not just me I am talking about as we have some world class folks in our club. Well, they dont see me as having any talent at all I guess. Yet alone wanting an autograph or saying let me buy you a beer. Sometimes coming back from a major event has me feeling pretty good about my hat size. Then I go to a club meeting and that hat falls over my ears.
     
  14. John Sheets

    John Sheets

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    I have a CBN wheel from D-Way and I like it, but I see only two significant advantages:

    1) Most importantly it doesn't need to be dressed, which I find to be a major PITA
    2) It definitely is nicely trued and balanced

    But remember that "doesn't need to be dressed" also means "can't be dressed".
    So be sure that your grinder shaft has little or no runout, because once the wheel is in position on the shaft, that's pretty much it. No truing, rounding, etc. can be done.
     
  15. Steve Worcester

    Steve Worcester Admin Emeritus

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    I had mine on a woodcraft grinder initially, and put blue painters tape on the face of the wheel and put a dial indicator on it. With a bit of measurement and moving the wheel adapters around, you can take some of any runout related to the shafts out.
     
  16. John Giem

    John Giem

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    It is interesting to read all of the opinions about what is the best method of sharpening our lathe tools. Everyting so far has been subjective, no actual measurements of sharpness have been made or how long the edges last. The cutlery industry has a set of standardized tests for knives that measure, with numbers, how sharp an edge is and how it degrades with usage. Until we have an equivalent standardized set of tests for sharpness and durability, we will continue to express opinions and perferences. Without repeatable measurements yielding numbers that can be compared, this type of discussion will never estasblish the 'best' sharpening methods or types of tool steels. I will admit that reading about the different OPINIONS is interesting and instructive but this approach is unlikely to arrive at a solid defendable conclusion.
     
  17. odie

    odie

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    Well......not really.

    Practical application is the best way to see what works, or not.

    I hone, because I've tested honed and unhoned edges on the same piece of wood at the same time. The better results were from the honed edge. It's easy to do this test any ol' time, and the honed edge (presumably the sharper edge) always wins with the more difficult to turn woods.

    We ALWAYS have a diverse set of opinions among turners, and there rarely is any subject where experienced turners universally agree.......so, the best thing to do is do what works for you, because there will always be those who will agree and those who disagree with the way you do what you do......

    ooc
     
  18. MichaelMouse

    MichaelMouse

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    Can only refer back to the comb analogy. A guy who tries to push the tool broadly into the work will have an entirely different result than the guy who lets the wood cut itself by sliding along the edge. This guy has an interesting take on the matter - it's the steel. Also has an aside for the honers as to why it seems to work. http://www.woodturnersamerica.com/i...-little-time&catid=99:jerry-wright&Itemid=149

    One final thought. I'm sure we're all familiar with the "steel" used on carving knives, and what it does? Takes the "set" out of the teeth, right?
     
  19. hockenbery

    hockenbery AAW Advisor Staff Member

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    John,
    Sharpening seems to be the one area where turners disagree the most.
    And much of it is undoubtedly due to a lack of science.
    And even if you were to design experiment it is a large multidimensional space with lots of value for each variable

    :)

    Steel type x flute shapes x grind types x wheel composition x wheel grit x wheel diameter x honing tool X honing method x materials to turn
    4 x. 4. X. 6. x. 4. X 4. X. 4. X. 3. X. 3. X. Hundreds. =. One heck of big problem to find the best answer. If you do each combination in 20 minutes on a piece of clear white pine that would take about 8 person years.
    Then do it for hard maple, cherry, cocobolo...

    Professional bowl turners I know are about 100% on using a side ground bowl gouge, then they split on preferred steel, preferred flute and on specifics of the grind.
    Most are now using a course 60 grit wheel for sharpening.. 15 years ago most were using a 100 or 120 grit wheel. Most use 8" wheels and I don't know any who honey heir bowl gouge.

    They got there through trial and error and having mentors.
    What is clear to them all is that they can turn more bowls with side-ground bowl gouge. So they all use it.

    Next they deviate of the finishing tools. Smaller gouges, scrapers, side-ground bowl gouge

    Science is great if it can be applied in a meaningful way.

    It's a big problem...
    Al
     
  20. Jim Carroll

    Jim Carroll

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    Optigrind CBN Wheels

    Getting back to the original question, I use the CBN wheels from Optigrind, yes I have a vested interest in them as I sell them as well here in Australia.

    Yes I do like them I think they are fantastic, they give a great edge right of the wheel. They are best used on a slow grinder but can still be easily used on a normal bench grinder.
    I use mine on a 6" Cruesen slow speed grinder 1400rpm and it runs a lot cooler than the white aluminium oxide wheels. You can still generate a bit of heat but the downside of that is you grind away a lot of steel.
    I also advocate the use of grinding jigs as this gives you more control and less time at the wheel trying to get the edge right.
    With a jig you can hold the tool securily and only use gentle pressure so less heat is generated.
    We had a turnaround in Wagga a little while ago and resharpened about 30 different tools, all were impressed by how easy they were to use and the edge straight of the wheel, and a longer lasting edge. As some of you know we have some really hard timbers here in Aus so the guys were happy not to have to resharpen so often.
    The wheels are not cheap but the biggest advantage is that once you set your jigs for different tools you will not have to do that again as the wheel is not dressed so angles will not change with reduction in diameter of white wheels.

    I have never found the need to hone my tools I leave that for my carving chisels where I am the motor and need that extra keen edge.
    As others have indicated a honed edge does not help your turning only wastes time from your turning.
    Get in ther sharpen your tools and keep turning.
     

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