40/40 grind

Discussion in 'Newbie' started by Dave Fritz, Nov 8, 2016.

  1. Dave Fritz

    Dave Fritz

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    I recently attended a demo by Stuart Batty and he showed the 40/40 grind done free hand. He mentioned you could come close with a Oneway Jig system. Can anyone recommend a publication or video that demonstrates using a Oneway Jig system on an 8 inch wheel that comes closest to the pure hand done 40/40 grind.

    I'm sorry to say I'm too shaky to grind free hand and need stabilization to grind my tools.
     
  2. George Rousis

    George Rousis

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  3. Jamie Straw

    Jamie Straw

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    You might do better than you expect, Dave. You have the platform to hold the tool at the correct angle. The main maneuvering is to keep the flute parallel to the platform but the whole time, the tool is pressed to the platform. It's very different from trying to grind a spindle gouge freehand the way Bonnie Klein et. al do where they completely leave the platform (or don't even use one). Tom Wirsing figured out how to grind a slight flat on the sides of his gouges so that he could start them out on their sides and swing to the middle and stay right at 40 degrees all the way. Perhaps someone here knows how he did that?
     
  4. robo hippy

    robo hippy

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    It has been a while, but I am pretty sure that Stuart rolls the gouge as he swings it from side to side. Took a 3 day work shop with he and his dad some years back. I know Ashley Harwood uses the same grind, and now trying to remember again.... The 'traditional' grind, I think is one where you just roll the tool, but there is no sweep to it. If the flutes don't roll on Stuart's grind, the wings get really thin. Ashley only sharpens from the left side of the grinder. This is because she only had the gouge on her right side. I use both right and left, so can turn and sharpen on either side.

    The most difficult part of platform sharpening is setting the angles. Every skill you need, you use when you turn. Still trying to get my platform sharpening video final editing done....

    robo hippy
     
  5. Jamie Straw

    Jamie Straw

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    Yes, that's how the flute (at the cutting point, or the being-ground point) is kept parallel to the platform. The diagram on the page that George linked is a useful representation.
     
  6. robo hippy

    robo hippy

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    Oh, it didn't translate to me..... I use a half round piece of wood with a free swinging needle in the center to demo this. Same thing with cutting, the part that is cutting or being sharpened is directly on the tool rest. The needle swings as you roll the tool.... Need to get the sharpening clip done.....

    robo hippy
     
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  7. Dave Fritz

    Dave Fritz

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    I'm familiar with how Stuart does it, does anyone know how to come close using a Oneway Jig?
     
  8. john lucas

    john lucas

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    I will go out to the shop right now and try to figure it out. I have a gouge that has the 40/40 grind so I should be able to play with the Wolverine system and see if I can make it work.
     
  9. john lucas

    john lucas

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    OK here is what is really close. I set the leg on the wolverine jig so it's on the first notch as seen from the handle side of the tool. The tool is extended 1 3/4". I adjusted the V arm to give me a 40 degree angle on the nose. I didn't grind my tool but it's really close to matching the 40/40 grind I already have on the tool. This is with a Henry tayler 1/2" U shaped bowl gouge. hope this helps.
     

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  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Great work, John. I also went into the shop to play around with setting up the Varigrind jig, but I don't currently have a bowl gouge that has a grind that is exactly like the 40/40 grind. Anyway here are some general guidelines for setting the Varigrind:
    • According to Doug Thompson you can come reasonably close to duplicating any shape grind that you want using a Varigrind by first adjusting the Wolverine arm to get the desired nose angle and then adjusting the protrusion of the gouge from the Varigrind to get the desired wing shape. He says that the leg angle of the Varigrind can be just about anything.
    • Here is the way that I go about it which isn't nearly as fast as the way that Doug Thompson would approach it, but I think that it gives you a wider range of adjustments.
      • First I start by setting the Varigrind arm to 45° which is the middle notch.
      • Then I set the protrusion of the gouge through the Varigrind to about 2" by eyeball
      • Next I adjust the Wolverine arm to match the nose angle of the gouge, or in this case set it to give a 40° nose angle
      • The amount that the wings roll over is adjusted by the protrusion of the tool through the Varigrind ... the longer the protrusion, the greater the roll
      • The leg angle adjusts the length of the wing. A small angle gives a long wing and a large angle gives a short wing.
    All of these adjustments interact considerably so it will normally take a few iterations to converge on the desired results.

    There's one important point that I need to mention regarding the Varigrind or any other jig: The jig only sets the desired angle, but it cannot control the shape of the grind. Controlling the shape is up to you.
     
  11. Dave Fritz

    Dave Fritz

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    Thank you John, exactly what I was looking for.
     
  12. john lucas

    john lucas

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    What I find is the angle of the arm on the Wolverine affects the side grind or the wings. Changing that shifts how far back the wings grind and somewhat how acute the cutting edge is. Then nose angle also changes the wings a little so you kind of have to deal with both. For a while I played with the length of the moveable arm when I was building my own jigs. That didn't seem to matter much unless you were really trying to be exact in matching a grind.
     
  13. Matt Reagan

    Matt Reagan

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    Dave,
    I took a class with Stuart a year ago. I've been using the wolverine exactly as John displays above. Stuart thought it was fine. Wish I could take that class again.

    Matt
     
  14. john lucas

    john lucas

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    that's good to know Dave. Next time it needs sharpening I may try using the jig just to see. I've gotten pretty good at hand sharpening that tool now. I use my Robo Rest and have scribed lines on it at 45 degrees to help align the tool.
     
  15. Dave Fritz

    Dave Fritz

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    Thank you both. I set it as you described and it works really well. I too have the robo rest and checked and the 40 degree setting is spot on with it. As I gain more confidence I may try to hand sharpen but I'd rather spend my time making things.
     
  16. Kevin Campbell

    Kevin Campbell

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    I have been watching this thread, closely. My issue is that I started out wrong, and got worse, on a bowl gouge. It ended up with a gouge, right in the tip of the nose. I want to be able to correct it as easily as possible. But, I think it would be very easy to make it worse. Any tips on what to do? I have a Wolverine system, and now I have new CBN wheels.
     
  17. Owen Lowe

    Owen Lowe

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    Can you post a close-up photo of the tool (side angle and top angle)?
     
  18. Kevin Campbell

    Kevin Campbell

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    I ended up sharpening it, as usual. It took a few times on the 80 wheel, but it eventually came out fine. I didn't do the swept back wings, like Stuart Batty, or Cindy Drozda. I want to soon, though.
     
  19. john lucas

    john lucas

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    Kevin If you have problems with a grind it's easy to correct. You simply grind longer in the high areas and less or not at all in the low areas. Here is my video showing how to correct grinding problems.

    View: https://www.youtube.com/watch?v=M9G16ylEZHQ
     
  20. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Another method that I have seen recommended:
    1. First grind the nose angle
    2. Then turn the gouge flute down against the wheel and grind the top profile of the wings
    3. Finally grind the sides of the wings until it just barely intersects the top profile
    This method is sort of a last ditch if things are so bad that John's method doesn't work. This method uses up a lot of steel so don't do it if you can salvage the edge following John's video.
     

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