A little "hard truth" for the newbies at AAW........sharpening gouges and scrapers:

Discussion in 'Newbie' started by odie, Jun 16, 2012.

  1. odie

    odie

    Joined:
    Dec 22, 2006
    Messages:
    4,424
    Location:
    Deep in the woods
    Hello again, Mark.......

    Pretty much "all of the above" is good, and applicable to the novice turner. I agree that keeping things limited and simple for beginners is a good thing.......but, I also believe that ALL the pertinent information that more experienced turners know, should be available to them. Some will make use of this information, and some will not.......but, it makes no sense to limit everyone to the smallest common denominator......does that make sense?

    Even if some information is not used for a duration of time, the learner will be well equipped to make progress if certain more advanced information has exposure to their thoughts.......even if it takes years for that information to ferment into something actually useful to them........

    ooc
     
  2. robo hippy

    robo hippy

    Joined:
    Aug 14, 2007
    Messages:
    1,867
    Location:
    Eugene, OR
    Odie,
    Yes, discussion it is, not debate. I was pretty sure you went from the grinder to the wood. I have used both my coarse wheel and finer wheel (80 and 180) for raising a burr, and get the more durable one from the coarser wheel.

    What kind if nose profile do you use? I have seen them skewed, round nose, and more of ) nose. Most of the time, I will use a swept back profile, like 1/2 of a swept back gouge. I can rough with the nose, and shear cut with the wing. For sure, a very handy tool when you know how to use it.

    The effects of honing go from Mike Mahoney 'more serrated cuts better' to the Tormek sharpeners 'less serration leaves a longer lasting edge.' I have wondered if there was any way to 'scientifically' measure edge durability, and cutting efficiency?

    robo hippy
     
  3. John Jordan

    John Jordan

    Joined:
    Jun 24, 2008
    Messages:
    283
    Location:
    Cane Ridge (Nashville), TN
    Home Page:
    So you have gone on and on and on and on in multiple threads about how the honed edge is superior, and how we were all missing out, and and then you use the scraper off the grinder for the final cuts??????

    That doesn't make any sense, but many things don't these days. :confused::D

    Thanks for saying something nice about me. :D

    John
     
  4. MichaelMouse

    MichaelMouse

    Joined:
    May 16, 2005
    Messages:
    3,540
    Sure it makes sense once you get off the "grit is it" train and look at the presentation. Remember that comb analogy? Even if he's got 40 to the inch scratches, they don't play at a shear angle like they do perpendicular.

    Makes sense to hone a carbon steel tool. It isn't brittle, so the edge will roll a bit, and needs the realignment and removal a hone can give it. Sort of like the steel on that turkey knife.
     
  5. Dale Miner

    Dale Miner

    Joined:
    May 13, 2007
    Messages:
    201
    Mickey,

    The statement "it isn't brittle" makes a lot of assumptions. For the most part, high speed steels have a higher Charpy value at equal hardness than carbon steels. In other words, M2 at 62 Rockwell C would be tougher than O2 at 62 Rockwell C. Higher Charpy = tougher = less brittle.

    I don't have a chart that makes a direct comparison of every type of carbon steel to every type of HSS, but if you want to muddle around on the net, here is a good place to start.

    http://books.google.com/books?id=Kw...page&q=charpy values high speed steel&f=false

    I actually think that the edge doesn't "roll a bit" at the grinder, but the burr of ground material remains hanging on the edge. Mechanically creating a cutting edge with another piece of hardened material will roll a very tiny edge of the parent material, but to have any uniformity to that rolled edge, the edge of the parent material will need to be uniform prior to rolling, hence the need to hone prior to mechanically 'rolling' the edge.

    Alan Lacer did a pretty extensive study on burrs from the grinder complete with photomicrographs. I don't recall the issue, but it was in the American Woodturner a couple of years ago.

    The only tools I hone are my skews, and occasionally a touch up to the point of the detail gouge. I do occasionally mechanically roll the edge of my hss scrapers following honing the edge but usually use the scrapers straight from the grinder. I only use scrapers in a shear mode.
     
  6. odie

    odie

    Joined:
    Dec 22, 2006
    Messages:
    4,424
    Location:
    Deep in the woods
    Howdy John......

    The sense in it..... is in the results! A finish that requires very little sanding is the objective, and that objective has been met. (As usual, this is not to deny that other turners have found their own methods of coming to the exact same result while using entirely different methods.) The difference is probably not just this one thing being discussed, but a combination of technical aspects, in conjunction with style and technique, but it really can't be disputed that the end result is the ONLY thing that really matters.

    You are welcome John. You, are one of many turners who have contributed to my advancement as a turner. Some of your input as an instructor, is information I still use, to this day! In the end, though, it is the student who insists on his own latitude in technical creativity, rather than the student who merely follows directions.......who makes all the discoveries!......:D

    One thing I've learned is, even among turners who have acquired the status you have attained......there is still a lack of agreement on the basics.......so, when you say it doesn't make sense, it's simply an indicator of opinion......and not what is working for any individual turner. Would you care to comment on Mike Mahoney's use of gouges straight from a grinder using a coarse grit wheel?

    The honed edge of the gouge is that which boosts the capabilities of the cut to the point where the scraper is only used as a final touch up of the surface, even though that final touch-up represents 90 percent of the work.....and the visual appeal. It is used fresh from the grinder, because that's when the burr edge is at it's sharpest, and most productive. Delicate application, and technique is key. I re-new the edge frequently, because, as you know, the burr does dull quickly. I don't wait until after the burr NEEDS to be re-newed. The point between "need" and "should" is critical to progress, and to overstep that boundary can be negative, or a "back pedal".

    ooc
     
    Last edited: Jun 20, 2012
  7. MichaelMouse

    MichaelMouse

    Joined:
    May 16, 2005
    Messages:
    3,540
    Not the grinder, the work. It rolls, harder alloys chip away.

    As to the quality of alloys versus HCS, these are turner-generated. http://www.woodturnersamerica.com/i...-little-time&catid=99:jerry-wright&Itemid=149

    http://www.woodturninglearn.net/articles/ToolSteel.pdf

    The chipping resistance number is particularly telling. Don't have to assume much when you compare the numbers.
     
  8. robo hippy

    robo hippy

    Joined:
    Aug 14, 2007
    Messages:
    1,867
    Location:
    Eugene, OR
    Well, there are burrs, and there are burrs. With the standard AlO wheels, you can get a 'flap' type burr that if you wiggle it back and forth some, it will break off. With the CBN wheels, the burr is different. You can not wiggle it at all. I can't tell you why there is this difference. The 'flap' type burr will cut, but not for long as it breaks off. If you really press the scraper into the stone, you can get a burr that rolls over a bit, kind of like a breaking wave. You can do the same thing with a burnished burr (hone off grinder burr, and burnish with a hard steel rod, or the Veritas burnishing tool) if you press really hard, and/or have the burnishing rod at a 45 or so degree angle to the top of the scraper, rather than almost just flush with the face. You can just barely kiss the bevel on the grinding wheels and get a smaller burr, but it is stronger than the heavy burr when you press hard into the wheel. The coarser burr from the standard grinding wheels does dull quickly for another reason, and this is my theory: a coarse burr will tend to catch micro shavings in the 'teeth' and while not dull, it doesn't cut well (teeth tend to be ragged, not refined like on a well sharpened saw). This happens to a lesser extent with the CBN wheel burr. I have cleaned them up a bit by rubbing the burr through some wood almost like you are sawing through rather than scraping or shear cutting. There is minor improvement. The fine burnished burr does cut better and more cleanly than one off the grinder, and you can turn the burr a couple of times before needing to go back to the grinder. I can turn one with a triangle burnishing tool, but don't do so well with a round one. Most of the time, it is just not worth the effort.

    Me to my dad, "Opinions are like rear ends, every one has one."

    Dad, "Yea, and some of them stink!"

    Me, "Yea, and some of them are pretty hot!"

    What cuts best? No way to prove any of the methods to every one's satisfaction. You just have to experiment.

    robo hippy
     
  9. odie

    odie

    Joined:
    Dec 22, 2006
    Messages:
    4,424
    Location:
    Deep in the woods
    That was a good read, MM.....

    I can't claim to be that technically aware of all the different steels, and how well they hold up. From my limited experience of what I have had the opportunity to use, I believe the M2, or similar HSS is the most useful range of steels we have available to us. I've used a few carbon steel tools years ago, and I don't think I'll get much disagreement that the edge holding ability isn't worth using them......that is, as long as HSS is available. If carbon steel tools were all I could get, I'd have no problem producing turnings that are the equal of what I do now......but, I'd have to work at it a little harder to get the same end result.

    I've purchased a few harder base steel gouges and scrapers (I think the designation was 2085, or something like that......I'm on vacation right now, so can't go out to the shop and look.) I couldn't comment on this steel's tendency to chip, although I suspect the chipping tendency may be correct. What I have noticed is the harder steels are noticeably more difficult to grind an edge. I believe the edge does last longer, but I'm not so sure the price to pay in difficulty to acquire and maintain the edge is worth the effort......and, the added cost is another consideration!

    For my purposes, I've pretty much decided to stay with HSS, M2, or similar. This is, IMHO, the best compromise of ability to grind, edge holding capability, cost, availability.....etc.


    ooc
     
    Last edited: Jun 20, 2012
  10. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,829
    Location:
    Cookeville TN USA
    Odie Once you get a good edge on the hard steels it's easy to maintain. I thought the same as you when I first got my Thompson gouges. Now I would not go back. I really would like to try the new harder thompsons or the D way that's hardened to 67R just to see how they do.
    Now that I've used the Thompsons for several years I don't even notice the difference in sharpening time between them and any of my other tools.
     
  11. robo hippy

    robo hippy

    Joined:
    Aug 14, 2007
    Messages:
    1,867
    Location:
    Eugene, OR
    The metal heads seem to agree that most of the steels will get to the same degree of sharpness, but some are easier to get there than others. When I compare the Thompson and D Way to the HSS, the wearability, as in great for roughing is way higher in Doug and Daves tools than in the HSS. For finish cuts, I still prefer a fresh from the grinder edge. It just works better. I haven't tried the V 15 yet, and don't know if I will. I did talk to Doug about it, and he said it is more expensive, it does tend to chip more, and is questionable as to weather it is worth the extra effort to make and worth the expense to the turners. I may have to get one, well, maybe more than one, and see how they work. Probably have to get a scraper also, but I may put that on hold till after I get some 'Big Ugly' scrapers made. Tantung steel (which is a cast metal), silver soldered onto some cold rolled bar stock. Not quite as hard as carbide, but you can resharpen it easily.

    I have been using CBN wheels for so long, I don't notice any difference in sharpening the different steels.

    robo hippy
     
  12. Dale Miner

    Dale Miner

    Joined:
    May 13, 2007
    Messages:
    201
    Mickey, again, your answer is more confusing than informative.

    "not the grinder, the work. It rolls, harder alloys chip away" makes no sense.

    Most tool steel alloys can be hardened to the point of brittleness, or annealed to full softness. Try making your turkey knife from a file, giving it a full water quench. The edge will chip away if you try to use a steel on it. Quench in oil and draw the temper back a bit, and you can carve away with only an occasional touch of the steel.

    Make a hook tool from O1, quench it in oil and try to use it straight from the oil. The edge will be so brittle that it will chip very easily. Draw it back to a straw color( approx Rockwell 55), and it will give good service. A Termite tool is essentially a closed hook tool made from HSS with a hardness of approx 62 Rockwell. The edge of the Termite is very chip resistant, indicating that it is not brittle. The edge of a HSS Termite will outlast the edge on a properly tempered O1 hook tool many times over.

    Your original statement was that carbon steels are not brittle and made no mention of chip resistance. You are now changing the basis for your claim that carbon steal is not brittle by citing an article that deals with chip resistance instead of brittleness. The woodturners america article you cited as supportive for your statement indicates the value is 'experience based'. Charpy values determine toughness and are laboratory measured. Also the article does not give the Rockwell value for the material when it is rated using the experiened based system. It is very possible that a hss material at Rockwell 62 will chip easier than a carbon tool at Rockwell 52. The wear resistance of a tool from either material at 62 will be much greater than one at 52, and the wear resistance of the HSS tool will be greater than a carbon tool.

    If you are happy with carbon tools, then by all means, use them. I think they are fine tools when used within their limitations. Generalized statements as to their superiority do little to inform without empirical data to explain the statements.

    The article by Alan Lacer that you cited is not the article that deals with burr development. It discusses the various manufacturers tools and the chemisty of the tools. The article does mention the qualities of HSS, one of those being sufficient toughness to withstand chipping. I did not see any reference in that article to carbon steel tools.

    Many people read this forum that do not have a background in metallurgy, and will form misconceptions from erroneous statements, or statements based upon a fraction of what is involved. If not for that possibility, I would not have responded to your "it isn't brittle" statement. There are many factors that enter into brittleness.

    I recall the saying "Wrestling with a pig in mud is pointless. In the end you will get dirty, and the pig enjoys it". I don't think it makes any sense to wrestle this pig any longer.
     
  13. John Jordan

    John Jordan

    Joined:
    Jun 24, 2008
    Messages:
    283
    Location:
    Cane Ridge (Nashville), TN
    Home Page:
    That's exactly how/why I use the grinder edge on my gouge. That's what I don't understand.

    I haven't used a carbon steel tool in nearly thirty years.

    I'm not going to keep on with this, as the pig seems pretty pleased :D, but one thing is certain: ANY method of sharpening that gives one some sort of acceptable result, that is done frequently and before its really needed, will put one ahead of 3/4ths of other turners. And yes, I made that number up, but its pretty close.:D

    Carry on.........

    John
     
    Last edited: Jun 21, 2012
  14. MichaelMouse

    MichaelMouse

    Joined:
    May 16, 2005
    Messages:
    3,540
    It does if you read it. I was not speaking of sharpening, but dulling, which comes from the bending of the points in use, rather than their breaking away. This is done by the work, not the grinder. If you look at the photomicrographs you see those teeth which the flat scrape presenters are using to sand their surface actually form the edge. Larger or smaller, according to the size of the grit that dug 'em, modified by the actual grain size of the metal. Certain alloys form larger internal crystals during the process because of the other metals, which, I assume is the source of the "carbon steel can be sharpened better" folklore. Might have been true with some early attempts to use other alloys compared to forged tools.

    As to the Lacer article, you see that "sufficient" impact toughness is a desirable quality. As is hardenability. They are two different things. You seem to be linking them, where he and others do not.

    OD, it's still more presentation than number of sharpenings. Proper presentation will minimize those trips to the grinder. I know more than a few folks who were using "dull tools" who were amazed at what happened when they changed the presentation of the same edge. I grind because the wearability - a third quality of HSSs - makes honing slow. The diamond hones are better than others, but still not as fast at a new edge as that India on carbon. Because of this, I have to say that I'm not sure but that carbon steel tools, stoned rather than ground, might last longer per inch than the HSSs. From observing people who use grinding jigs and look for no 'facets" as their criteria, might last a lot longer.
     
  15. odie

    odie

    Joined:
    Dec 22, 2006
    Messages:
    4,424
    Location:
    Deep in the woods
    John......

    It would be easy to understand through simple experimentation.....

    Take a bowl in progress, preferably from a difficult species, and do a test cut with a gouge straight from the grinder. Then regrind and hone the same gouge and test again.....same bowl, same speed, same everything. If there is an improvement, then honing is worthwhile, if there is no difference, then it isn't......pretty simple, really! ;)

    While doing this test, I've found the sharper edge of the honed gouge left a better, more cleanly cut surface.

    For me, and my purposes, the honed edge is the better way to go. We all have complicated differences involving technique, style, tool choices, physical differences.....and on, and on, and on........ Because of all the possible differences, I have from the beginning, understood that what is best for me, may or may not be what's best for everyone. My purpose was to simply expose my methods and beliefs to those who will listen. My way of doing things involve a little more work and effort......and, for the results I'm getting, it's worth it!

    It was never my intent to suggest that my way would be better for everyone else, or for that matter, anyone else.....but for me, it is! For those who are still yet undecided on this, I'm putting my experiences forward for exposure...... I would imagine those who actually do some testing will be divided into those who agree that a honed edge produces the better cut, and those who don't. Without being exposed to an alternative point of view, some of these people will go on forever without ever knowing something simple, like honing, might enable them to see some improvement in their own turning.

    Your final point about 3/4 of turners waiting until past when they should be sharpening is what I suspect, as well......I don't instruct individual students, like you do, but I've come to this same conclusion from the input I see here........and, because human nature is what it is! :D

    ooc

    BTW: It's been about 30 years since I've used carbon steel tools, as well. There is the occasional use where I use them for a specialty purpose, because they do grind and shape a little easier........I wouldn't buy one. Are carbon steel tools still available?


    (Sorry, no spell checker on this computer.....I'm on vacation!)
     
    Last edited: Jun 22, 2012
  16. Who says it's only the pig that enjoys the wrestling? ;)
     
  17. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,829
    Location:
    Cookeville TN USA
    I enjoy mud wrestling but I don't remember any pits at the event I went to. :)
     
  18. Thomas Stegall

    Thomas Stegall

    Joined:
    Feb 3, 2011
    Messages:
    164
    Location:
    Niles, IL
    Another fine mess...

    While I appreciate Odie's intent to provide information to new turners, and sharpening is certainly an area lacking, it seems to me there are a few basics that I think should be mentioned. Feel free to correct me if I'm wrong;

    #1 A good cut with a reasonably sharpened cutting tool will usually provide a better surface than scraping with an equally sharp scraping tool.

    New and not so new turners will get a better surface if they develop sufficent tool control with cutting tools that they don't need to follow cutting with scraping in the first place. (obviously reaching into some areas or presentation angles require scraping). This I believe is the most important skill and most overlooked issue. One of the first lessons I give is to have a student turn a specific shape without scraping or sanding. The shape and surface quality of a piece straight off of cutting tools will tell you alot more about the skills of a turner and what needs to be learned.

    #2 A distinction should be made between the usefulness of honing for final cuts vs. stock removal.

    While this may be obivous to us, to a new woodturner this assumption of understanding may be missed. Some pieces I have hollowed were sufficently large and turned green to a thin final thinkness requiring the hollowing to be done in a single day, taking 8-10 hours. If I stopped to hone every two minutes during the bulk removal, I wouldn't get anything finished.

    #3 For new woodturners it does little good to get them to achieve 99 percent of possible sharpeness of a given tool, if their tool control is still at 40 percent.

    What they need is the ability to get a tool reasonably sharp, and then they need to stand at the lathe and turn, turn turn.

    #4 Excellent Tool control trumps a razor sharp tool every time. A fairly dull tool in the hands of a master will do better than a razor sharp tool out of control in the hands of a newbie.

    Basic sharpening skills are absolutely essential, but the idea that new turners who can't cut a basic smooth curve with a gouge need to hone their tools after every two minutes (as the example given) seems to be putting the cart before the horses.
     
    Last edited: Jun 25, 2012
  19. hockenbery

    hockenbery AAW Advisor Staff Member

    Joined:
    Apr 27, 2004
    Messages:
    4,310
    Location:
    Lakeland, Florida
    Home Page:
    Thomas,
    Good points!!
    I think this thread has little value for the new turner.

    My teaching technique is similar to yours
    With beginner I concentrate on tool use and getting a clean surface from the gouge
    A couple of basic cuts, body movement, sharpening with a jig, and hand positions.
    With intermediates I concentrate on form and advanced tool usage.

    With beginners it is important not to tell them too much too fast.

    Al
     
    Last edited: Jun 25, 2012
  20. odie

    odie

    Joined:
    Dec 22, 2006
    Messages:
    4,424
    Location:
    Deep in the woods
    Thanks for input here, Thomas

    I also agree with these points......with the exception of point #1........

    A scraper IS a cutting tool, when used to it's full potential as a finishing tool.

    We, more advanced turners, who have taken this further than the original concept, probably have taken this far beyond what could be useful for all but the most astute of basic turners. I'd have to agree with that point, however the degree of sharpness has merit for most all basic turners, in that it does increase their potential. This is not to acknowledge that many of them will not take advantage of having a sharp tool.......but, there will be some who will. It's true that there are many other things to learn that are an absolute necessity, but creating a sharp edge from which to build on the other skills, IMHO......is also a necessity!

    ooc
     

Share This Page