Tool Edge Micrographs

Discussion in 'Woodturning Discussion Forum' started by Jeff Gilfor, Jul 22, 2014.

  1. john lucas

    john lucas

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    There you go Robert. In about a year I could have it done. :)
     
    Last edited: Aug 2, 2014
  2. hockenbery

    hockenbery AAW Advisor Staff Member

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    John,

    I think if you just do a bunch of peeling cuts slight variations in your movements will be negligible as long as you use the same lathe speed.
    The peeling cut pulls into the wood as you push the tool up and over the rest to maintain bevel contact.

    Use a 2.5" diameter cylinder between centers with a spur drive. Part in to 1/2" diameter leaving sections a little wider than your tool.
    Peel a section from 2.5 down to 1/2" taking off an inch of wood.
    If you set up a video camera and digital timer with a hundred of a second read out in the shot you can review the time for each cut.
    You can check the variation in the time.

    Now you might use each tool in turn. So any change through repetition is distributed and not all given to the last tool.

    The wood removal will be the same within an 1/32"
    The feed rate may vary a little but I think with your tool control it will balance out and the timer will tell you.

    Al
     
    Last edited: Aug 2, 2014
  3. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Just as a guess, I would say that John isn't interested in this becoming a masters thesis project. :D

    Force feedback is the parameter that would be needed. All of the others are irrelevant to the control system, but might be of general interest to somebody. Unfortunately, force feedback is sort of the Achilles heel of feedback control system design. No matter how force is instrumented, it is a very noisy signal with bias offsets and quadrature components which means, in addition to other things, heavy filtering which translates to out of phase response and marginal stability at best. My experience with force feedback in the control loop is that it is a disaster looking for a place to happen. There have been many attempts using sophisticated adaptive Kalman filtering and whatnot with just as dismal results.

    The tool tip holder would be child's play in comparison.

    I am nor familiar with Adreno or Adrion.
     
  4. Gretch Flo

    Gretch Flo

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    Phd thesis

    John -is your head spinning+??? Tooooo much info. Fortunately I am so uneducated about this stuff, my head is only spinning, not exploding!!!!
     
  5. KellyDunn

    KellyDunn

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    John, I am going to suggest two things in your test. A set time for each tool and then your own thinking of when the tool is dull. A set time will be good enough to see wear. Your own thing of when the tool is dull is way to variable but still I know when in the same wood a tool is not giving what I want. but that can come when I notice. Maybe I was into it and it took a bit longer to notice? I will say as others have that the better steels do last longer. But how much longer versus price? and what works for each of us. Please use real wood in your test. Mark was right on about manmade woods. Like sticking your tool against a grinder. I also need to look up Alan Lacers article to see how much of this he covered.
    I recall the article. It was on honing and buffing an edge versus right off the grinder. And then photos of the cuts gotten. So nothing about wear. On that note most of my turning is right from the grinder. a special cut I hone and polish. That edge is gone in moments. But did what I needed. It makes a sizzle sound. and like in Alans article the cut is smooth on smooth. But not worth my time unless needed.
    Now the tests on wear with a microscope sound way cool. But when you start getting hops and feel the edge and it feels sharp but wont catch your finger nail? Grinder dog city for me. My 2c. Go for it guys.
     
    Last edited: Aug 3, 2014
  6. odie

    odie

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    Kelly is making a point, here......

    How sharp does it need to be, and when is it dull? The answer to that will depend on what the requirements are, and who decides what dull is. For myself, I always start with a tool that is as sharp as I can get, and when I decide to resharpen all depends on what my requirements are. For instance, when I'm roughing a bowl or just searching for a general shape on a seasoned bowl, the concept of "dull" will vary with the requirements of the moment, and will dictate when resharpening is necessary. That will vary.....and, it will vary in ways that can't be defined as an absolute. The only thing that is an absolute, is the need for a surface that requires a minimal of sanding....at that point when you put your tools down and start sanding. The species of wood will respond differently with different users, techniques, and levels of sharpness. You can take oak, Bocote, maple, ebony, and all things being equal, will not have the same results on the end grain. Some species, or even individual blocks of wood, will require more sharpness to have the same refined results. Even grain structure, such as plain/straight, burl, spalting, quilting, etc., will all have different needs in tool sharpness (and user skill), to achieve the targeted level of surface refine-ness.

    For me, since I always start with extreme sharpness, all those variables don't really have much mental calculation to it.......when I no longer am getting the results I want, I resharpen, or re-hone......a simple concept, really. What is different, are my needs may not be the same as what someone else perceives their own needs to be........;)

    ooc
     
  7. john lucas

    john lucas

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    I don't drink but I'm thinking about starting now. Since the edge retention test is an after thought of my original test which was simply to find out if the different steels could be sharpened to the same level Done that
    The edge test needs to something g I can do and get it over with so I can get back to turning.
    I think I can turn the ball bats by using peeling cuts to get down to size and the. Planing cuts to finalize the shape. If I can't tell when it gets dull with any certainty I'll just turn the same number with each tool. The. Look at the photographs and hopefully see some difference
     
  8. hockenbery

    hockenbery AAW Advisor Staff Member

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    John,
    This Keeps it simple. With the same wood and same lathe speed you should be fine.
    Your technique is consistent and won't introduce any significant variation.
    I would suggest running a video with a digital time in the background.
    One thing to add is examine the quality of the wood's surface both on the first bat turned and the last bat turned.

    Interested in seeing your results.

    Al
     
  9. hockenbery

    hockenbery AAW Advisor Staff Member

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    John,
    One more thought. You might make a reference mark on the top of each tool to use for the planning cuts.

    If you are like me you shift the tool cut to a sharp edge without thinking about it.
    I think for this experiment you want to cut in the same place on the tool.

    Al
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    .... or, just use the tool as you normally would. There will still be parts of the edge that don't get used and you can make before and after comparisons of the whole edge -- some parts will look the same and other parts will show the results of normal use.

    Have you had time yet to think about ways that this data can be used to benefit the reader? Maybe the answer isn't so much to do with the steel that we use nor the sharpening system, but rather how well and often we sharpen. Maybe it would be useful to have photomicrographs that show the wood surface when the tool is sharp as opposed to what it looks like when we decide that the tool isn't cutting well. These are subjective things, but so is everything else.

    ... just a few rambling thoughts while I eat my Wheaties this morning.
     
  11. Sergio Villa

    Sergio Villa

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    There is one variable that can be important: The distance of the edge from the original edge, i.e. how much have been already ground. A tool is hardened by heating and cooling but this process is influenced by the thickness of the steel and the distance from the surface. There is a gradient in the heating/cooling process that proceeds from the surface to the center of the steel. Thus there is a variation of the final hardness in the same tool and between tools.
    Besides every sharpener has his/her touch and what is the result of one person often cannot be reproduced by another. What really counts, in my opinion, is the starting grit of the sandpaper: non need for sanding = good tool. But...one moment, when there is no need for sandpaper? I feel there will be the need for another test...
     
  12. Bill Boehme

    Bill Boehme Administrator Staff Member

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    That would depend on the type of tool, the manufacturer, and the heat treating process. For most tools, the cutting edge is on the surface. The skew is an exception. Some manufacturers use induction heating for tempering and only harden and temper the first couple inches or so. Others treat the entire tool for a long period of time, so the "gradient" would be essentially nonexistent. In any case, I believe that the metal is heated to the Curie point which is easy to detect and assures that the steel has all been sufficiently heated.
     
  13. Sergio Villa

    Sergio Villa

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    Yes, heated but what about cooled? Also, the hardening/tempering process is done before sharpening and a tool at a time thus the first section, lets say less than the diameter, is heated and cooled more rapidly than the rest of the rod. Than there is the cryoprocessing...
    PS: that would depend on the type of tool, the manufacture, and the heat tthreating process.... It seems to me that you agree with me in essence. Or not?
     
    Last edited: Aug 3, 2014
  14. Robert Elliott

    Robert Elliott

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    I agree, but this is not a project for a PhD candidate.

    I agree with the rotation of the wood in rpms would be very highly garbage in garbage out and a wast of data cpu time. Given the lathe's controller. What might be more reveling would be the "frame by frame" view of the video looking at the cut of the shaveings. Of course it would be nice to have a 4k ultraHD ,high-speed camera on the other end of the endascope.
    .
    My tablet automatic spell check screwed up. I was thinking of the Arduino.

    PS, I am a retired research/manager and Engineer. I have been turning since before bowl gouges.
     

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