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Sharpening wheel rotation direction.

Discussion in 'Woodturning Discussion Forum' started by Wayne Spence, Mar 8, 2010.

  1. Wayne Spence

    Wayne Spence

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    Last year I bought a Woodcraft lo speed , 2 wheel sharpener. After sharpening with it for a few days I realized that the direction of rotation was going down into the gouge and not going up to the blade. I checked back at Woodcraft and found the direction of rotation for the Delta 8" was the same way, I have not checked others. The sharpening has been as good as expected, I use a Wolverine jig. It seems to me that the direction of rotation should be up when looking straight on at the wheel. I think this should be especially true for woodturning tools where a burr is so important. Maybe this has been discusssed before but the woodturners comments are always worth reading.
     
  2. Matthew Clarke

    Matthew Clarke

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    I've used grinders where the wheel spins towards the edge of the tool and machines where it spins away from the tool's edge. According to the research quoted by the manufacturer of the Tormek grinder, the direction that the wheel spins does not make a whole lot of difference in the resulting sharpness of the tool or the size of the burr. When I want a finishing 'cut', I don't use the burr on a scraper right off of the grinding wheel. Generally I will refine it so that it doesn't take such an aggressive cut. The point is that it is the turner who, in the end, controls how well the tool cuts—regardless of the direction the wheel spins.

    Matt
     
  3. john lucas

    john lucas AAW Forum Expert

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    All of my grinders rotate into the blade, or down. As long as the tool is above the center there isn't a problem.
    I plan to set up a strip sander to sharpen carving tools and that will rotate upwards, away from the point. These will have a much sharper angle.
     
  4. Dave Moore

    Dave Moore

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    Wayne, I think just about every bench grinder on the planet has a rotation down toward the toolrest. Otherwise there would be a tendency for the rotating stone to pick the tool up off the rest. It would chatter I think.

    I use a Wolverine jig too, and think that it would be a lot less stable if the stone rotated the other way: with the very light touch needed to just dress the edge it would be hard to prevent "bouncing" as the tool was lifted by the wheel rotation.

    I'm guessing though, I've never actually tried it. Maybe someone has and will report that it works great, you never know.
     
  5. steelguy

    steelguy

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    Grinder Wheel Rotation

    As pointed out, grinders tend to rotate down toward the tool rest, keeping the tool on the rest. With this rotation the burr forms on top of the tool. This is due to the deformation of the edge on the unsupported top surface of the tool as the wheel moves into it. This is counter-intuitive to many who assume that the burr forms from material dragged off of the surface by the grinding action. There are turners who turn their tools over when grinding. This however results in a rather awkward stance, but results in a relatively burr free edge.

    Jerry
     
  6. Bill Boehme

    Bill Boehme Administrator Staff Member

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    As mentioned by the other responses, all bench grinders rotate the same way.

    With a Tormek, there are two different tool rests so that sharpening can be done either towards or away from the edge. The choice of which tool rest to use depends mainly on the bevel angle of the tool. With a large bevel angle, there is less tendency to chatter if the wheel is rotating away from the cutting edge. With a shallow bevel angle, the tool is easier to control if the wheel is rotating towards the cutting edge. The cutting edge on a slow speed wet grinder is being applied to the stone with somewhat more pressure than with a dry grinder. On the other hand, the contact pressure is very light on a dry bench grinder so the tendency to chatter or pull is not as great and so it is not necessary to have the stone rotate away from the cutting edge.
     
  7. Bill Weaver

    Bill Weaver

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    I would be concerned about my personal safety. The wheel turning in reverse rotation would make any tool rise off the rest or wolverine jig. With pressure a sharp tool could come right back at your face.
    I think OSHA would love this discussion.
     
  8. MichaelMouse

    MichaelMouse

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    Not many carvers here, I guess. Carving with steel demands an extremely sharp edge, and I think most carvers use, if they use electricity, a rotating strop for the final work. Strops rotate away, most are semi-rigid, and use some form of abrasive in a wax or grease base, like the buffing compounds for wood. One such is demonstrated here http://www.woodcraft.com/Family/2020509/Koch-Sharpening-System.aspx for those with lots of money or the true fanatics. Nora Hall, one of the premier old-school carvers, who appeared on Roy Underhill's show a few months back, endorses the system. I've used hard felt or leather and Chromium Oxide green stuff for years, but this takes it one step finer. Might be Cerium Oxide.

    Since you're really lapping the edge when the wheel rotates away, there's no danger of taking too big a bite. It's impossible. Putting the off hand over the tool on the rest does the same for grinding that it does for turning, keeps it from bouncing.
     
  9. Wayne Spence

    Wayne Spence

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    Wheel Rotation

    When I first started turning 4 years ago I used the same setup I used for 40 years doing flatwork (as you roundheads call it) and carving chisels. That setup was/is a 8 inch silicon carbide wheel on a reversible motor , 1750rpm, with a mandrel geared down to 850 if needed. I always ground /sharpened plane irons and chisels with the wheel going in reverse, that is up. Honing was then done on water stones and leather strops. I very seldom used the wheel on a carving gouge . Finally I went to a cardboard wheel at 3600 rpm with ceramic oxides for the carving gouges. All of these for the carving gouges move away from the blade. This will freak out some of you even more, I sometimes sharpened on the side of the SiC wheel.

    The local turning mentor Pete Holtus told me to switch to the aluminum oxide wheel at low speed several times before I broke down and finally bought one.

    MM-Nora Hall lives here in Denver and I have taken her advanced carving class. Like many Europeans she thinks all Americans should start out with her basic class, as we are not stupid but a little backwards. We don't (or didn't) use the system you are speaking of as the classes were held at Rockler and they handle a different system.

    This forum is as much fun as turning. Thanks for the banter.
     
  10. Randy

    Randy

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    I too have the Woodcraft slow speed grinder and the best thing I did for it was to buy the Norton 3X wheels. Much better than the white Chinese ones that came with it. I also notice the tools does not "bounce" as much and the Norton give a much superior grind.
     
  11. MichaelMouse

    MichaelMouse

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    I came back to the SiC wheel after experimenting with the soft bond types that just made a mess of the table under the grinder. Don't think any of the carving tools have seen a wheel since the 1" #7 that took a bit of concrete about five years back, though. I use a bigger mat now.

    Europe had a fine apprentice system before people traded their obligations in on rights. Won't see its like again. Worked with a man in our area whose completion certificate had the eagle and swastika on it, and his training even involved carving. Can't say I've put a claw on a ball since he passed on, but he knew nearly every aspect of woodworking.

    Including, since this is a forum devoted to carving rotating material, the turning of architectural columns and split columns for interior work. Headstock on one side, tailstock in the center of the shop, and away we went.
     
  12. Don Geiger

    Don Geiger

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    Grinder vibration and tool bounce

    Two things you can do to to any grinder supporting any types of wheels are to:

    1) Get rid of the plastic bushings that are often supplied to make up the difference between the o.d. of the grinder axle shaft and the i.d. of the wheel and replace them with metal bushings (I use 5/8" i.d. X 1" o.d. X 1" L. drill bushings on my Delta).
    2) Ensure the wheels are concentric to the axle as they are mounted and while they are at operating speed. My "Geiger's Wheel Truing and Dressing Solution" does a great job of this easily and quickly.

    Don Geiger
     
  13. Robert Manning

    Robert Manning member

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    Wayne, would you be kind enough to elaborate on the cardboard wheels? I need an easier way to sharpen my carving gouges.

    Did you make them? . . . .or is this what you are talking about?
    http://www.sharpeningwheels.com/products.html
     
  14. steelguy

    steelguy

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    Robert: You also can use diy wheels made out of MDF - bandsawn and turned round. Load with polishing rouge - the normally sold to use on cloth wheels. They come in numerous grits.

    Jerry
     
  15. Don Geiger

    Don Geiger

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    MDF Carving Tool Hone

    Here is a photo of a multi-layered, multi-profile carving tool hone that fits into a chuck. You run the lathe in reverse at a slow speed and present your tool with the edge away from you so the hone is moving in the direct from the tool to the cutting edge.

    You can make it out of scrap MDF to any profiles you want and change them any time you want. Notice that the layers are held together with a threaded stud and a wing nut so you can add, delete or change the order of the layers easily.

    You load it with an abrasive paste (SS polish, rouge or whatever) and re-new it occasionally.

    This way you don't tie up a grinder and you can run at speeds you want instead of what the grinder speed happens to be.

    Don Geiger
     

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  16. Wayne Spence

    Wayne Spence

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    Rotation

    Robert-Go to www.sharpeningwheels.com, The place is in CA. Woodcraft handles them for about $44, the kit. they recommend at least 3000rpm, I had a 3600 rpm motor and so used it. I also use a leather wheel for final stropping, it may not be needed but I feel it makes up for past mistakes, probably not true. Any questions get back to me. I had one carver who used it once and threw it away. Another who swears by it.
     
  17. Robert Manning

    Robert Manning member

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    Carving gouge sharpening

    Don, many thanks for posting that photo. That looks exactly like what I was looking for. MDF can easily be custom shaped and multiples installed and removed from the lathe, with adjustable speed.

    I looked on a carver's forum, and one carver makes his own cardboard wheels by laminating chipboard (like the back of a scratch pad) with a 50/50 mix of white glue and water, and lets it dry for a few days. This could be used in conjunction with your MDF/lathe hub. Some people laminate masonite as well (probably the untempered type). Anyway, this cat buys the rouge at Sears and the green compound at Lowes @ $4 per bar ea.

    I checked my library and found an old Fine Woodworking issue where someone glued leather onto, probably MDF for stropping. Lots of easy homemade options.

    Many thanks, Jerry and Wayne, I'm going to build a version of Don's MDF method and probably laminate a cardboard wheel so I can test that as well.
     
  18. Don Geiger

    Don Geiger

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    MDF Honing system

    Robert:

    The honing system in the photo resides at Arrowmont. Mark Gardner and I assisted John Jordan with a class there a several years ago and Mark, who does a lot of beautiful and very creative carving, demonstrated how to use it.

    I have one of the "Razor Sharp" systems from Woodcraft, but have never used it. To do so means I would have to remove a grinding wheel from one of my bench grinders and put the Razor Sharp system in place. Then replace the grinding wheel true it up etc. when I'm done.

    The home made MDF hone is much easier; just put it in the chuck, reverse the lathe rotation and it's ready to use. Plus you can make as many profiles as you wish.

    Don Geiger
     
  19. Wayne Spence

    Wayne Spence

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    Honing Systems

    Robert-You can also make a good honing device using something like hard maple. Turn the maple to match the sweep of your gouge on the lathe. Then run the maple at reverse rotation on your grinder motor.
     
  20. Robert Manning

    Robert Manning member

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    Since I had to wrestle the MDF out of the dreaded corner, I roughed out four 3/4" by 10" blanks and glued one of my maple hubs onto one of them. Sears had every color of compound at $2.19 ea. for a 4 oz. bar, so I bought red rouge, tripoli and a green one. I turned a cove in the edge of the disc with my scraper held at a slight negative angle which made the MDF cut just like butter, and charged it with rouge. It made the gouge pretty sharp in short order, but the rouge seems to have trouble fully charging the wheel.
     
  21. Don Geiger

    Don Geiger

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    Loading rouge

    I haven't used the rouge you selected, but I believe that the MDF or whatever the base wheel is made of, will evenutally reach a saturation point. Once that has occurred, you will only need to add sparing amounts to keep it that way. I use a SS polishing compound on my MDF.

    Don Geiger
     

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