Elllsworth to Wolverine jigs

Discussion in 'Tutorials and Tips' started by Jed Dyke, Aug 30, 2012.

  1. Jed Dyke

    Jed Dyke

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  2. Bill Blasic

    Bill Blasic

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    Jed,
    Nicely done but wouldn't it have been easier to make a little vee block to fit into the vee arm to raise the jig to the right height?
    Bill
     
  3. john lucas

    john lucas

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    I agree with Bill. Put a magnet on the V block to hold it in place in the V arm of the Wolverine.
     
  4. robert davis

    robert davis

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    elsworth to wolverine

    john, that is what i did. i made my elsworth jigs. one for each size gouge
     
  5. Jed Dyke

    Jed Dyke

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    EtoW Jig

    Since I made this jig I found that all I had to do was lengthen the Ellsworth leg and change the distance to the grinding wheel. ...but building the jig out of wood was more fun than metal working!
     
  6. Don O. Jr.

    Don O. Jr.

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    Well done, quick to set up and repeatable-which is the overall goal.
     
  7. Steve Worcester

    Steve Worcester Admin Emeritus

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    Vee block works, or use a Gieger jig to get you more adjustability
     
    Last edited: Oct 28, 2012
  8. odie

    odie

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    Jed, or anyone.......

    Why would one prefer the Ellsworth jig, if he has the Wolverine base?

    Is it a simple matter of having these two items, and the need exists to adapt?

    ooc

    edit: BTW: I can understand the pleasure of investing the effort and doing the work, and it looks like you did a real good job of it!
     
    Last edited: Oct 28, 2012
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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    There is a an easier solution than adding a riser block mentioned by several others. It sounds like Odie's suggestion is about the same as what I am suggesting:

    • First, forget about making some sort of adapter and instead just put the arm of the Ellsworth jig into the notch of the Wolverine arm
    • Next, adjust the Wolverine arm so that the bevel of the bowl gouge contacts the stone at the desired angle which is nominally 60°
    • You can then mark the Wolverine arm with a piece of tape, but periodically the arm will need to be recalibrated as the stone wears
    David Ellsworth's description of a fixture for his jig was based on not already having something like the Wolverine available. Unfortunately, this has caused a lot of people to construct unneeded adapters for setting the jig distance.

    If you find that there is a weld blob on the Wolverine arm "V" right where the tip of the Ellsworth jig arm needs to rest, you can fix that by drilling a shallow dimple for the tip of the Ellsworth jig arm.
     
    Last edited: Nov 1, 2012
  10. Steve Worcester

    Steve Worcester Admin Emeritus

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    Bill, the Oneway pocket is too low to get the same wing angles as on his setup. BUT I think his current directions do show adding a vee block in the pocket to elevate it to get the proper sweep and swing.
     
  11. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Why do you say that, Steve? Is there a problem with the wheel shroud getting in the way? I have used it on my grinder without any interference issue. It means holding the tool handle somewhat lower, but if you have the grinder close to the front of the workbench/table, I don't think that you would encounter any interference issue.
     
  12. Steve Worcester

    Steve Worcester Admin Emeritus

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    to copy exact the Ellsworth grind, on a Oneway setup, you need more height. You have to add a block into the pocket of the Oneway, effectively lengthening the rod from the jig.
    Same principle as the Gieger setup.
     
  13. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I will look further into this and report back with any findings. I have done CAD drawings to compare the two and have not seen any functional difference. This is not saying that I am right, but at the moment I am leaning that way. A wise man who I one worked with had a saying, "When given the choice between admitting being wrong or proving that oneself right, most of us get busy on the proof". He was a very wise man.

    One thing to think about is that the grinding wheel is round and the concepts of horizontal and vertical are only artifices to help visualize things. Since I dealt with things in space where some of the common orientation references we use down on the ground like the gravity vector and level are no longer applicable, it meant visualizing things differently and inventing alternative frames of reference. So, we shall see whether I am "lost in space" or "thinking outside the box". Do you think that the AAW might give me an EOG grant to study this issue? :D
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

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    OK, I think that I see what you are saying is that the rod on the Ellsworth jig will hit the sides of the Wolverine "V" as indicted in the picture below unless it is raised up a bit.

    wolverine.jpg

    Now that you mention it, I think that I did have a small piece of wood in the notch to keep the rod from hitting the sides of the "V". It has been a long time since I used the Ellsworth with the Wolverine and I had forgotten about that detail. It doesn't require much -- just enough to clear the sides of the notch.

    I have been using my Tormek for the past several years and there is a setting with their jig that allows it to make a very good approximation of the one using the Ellsworth jig. It is quite close to the real deal and I am not sure if anyone besides D. E. himself could easily tell the difference. I have been wanting to make a set up to use the real Ellsworth jig on my Tormek, but it is one of those low priority things that I may eventually do if I ever find that "round tuit".
     
  15. Steve Worcester

    Steve Worcester Admin Emeritus

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    Not in hitting the sides, to actually raise up the jig to achieve his geometry. If it is low, the wing angle is not enough.

    http://www2.woodcraft.com/pdf/77B61.PDF

    It has been a long time since I used it, but that was my understanding at the time. Some may have to do with how the Oneway setup is installed, and as an FYI, if you are going to use a Stuart Batty platform, move the Oneway back about 25mm
     
  16. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I am familiar with the Woodcraft instructions that show the drawings made by David Ellsworth and I think that a lot of woodturners have read more into what the holding fixture does than is actually the case. The two dimensions that are given: four inches down from the center of the grinding wheel and seven inches horizontally from the face of the wheel are strictly for setting the angle of the grind at a nominal 60° at the nose without the need for an angle measuring gauge. Once the angle has been set, the shape of the grind on the wings is primarily determined by the length of the pivot arm and the protrusion of the gouge tip from the jig.

    Here is a real world example: let's assume that we have a brand new Norton SG grinding wheel (OK, maybe this is more like dream world) that has an 8" diameter. See Figure 1 for the set up as David Ellsworth describes it.

    Official-Ellsworth-Fixture-web.jpg

    The four and seven inch dimensions place the pivot point point at approximately 11¾" from the center of the grinding wheel. That is the critical dimension to get the desired nose angle of 60°. See the Figure 2 depicting this right triangle relationship -- one side is 4" long and the other 11" (7" offset + 4" radius = 11"). The resulting hypotenuse is 11 11/16". The thickness of the pivot arm increases this slightly so I say approximately 11¾" as being close enough for all practical purposes.

    Ellsworth-triangle-web.jpg

    Something tells me that, David, being a clever person knew it would be easier to follow his instructions if connected to things that we normally relate to -- like vertical and horizontal. So, this was a convenient way of locating the pivot point at the right distance.

    But, given that the wheel is round, we do not necessarily need to have the 4" side of the triangle vertical nor the 11" side horizontal if something else is more convenient. The important thing is to have the pivot point located at the right distance so that the gouge will have a 60° bevel angle on its nose. From there, the size and shape of the jig takes care of the right presentation angle along the wings of the grind. And, we all know the rest ... it is up to us to not grind away too much metal and mess up the shape.

    Suppose that instead of being level, the 11" leg of the triangle sloped down some arbitrary angle of about 16.5° and the once vertical 4" leg correspondingly moved so that we still have a right triangle with a hypotenuse of about 11¾". Would that make any difference? See Figure 3 below that illustrates this.

    Ellsworth-with-Wolverine-and-triangle-web.jpg

    This "something else" that I mentioned could be a Wolverine fixture. On my grinder its height is approximately as depicted in Figure 3 above. On another grinder, the height would be slightly different. The distance between the positioning arm and the wheel axis does not matter so long as the arm can be adjusted to position the pivot point the right distance from the wheel center. Even more to the point is that the distance from the pivot to wheels center is just an artifice for setting the correct bevel angle on the nose of the gouge. Now since we realize that, we can dispense with measuring distances and simply set the arm length to give us the desired bevel angle of 60° or whatever we desire if we prefer something a bit different than that.

    BTW, the dimensions given by DE are not sacred. Fabrication tolerances makes each jig slightly different which means that the nose angle will be different for each jig. Additionally, as the diameter of the grinding wheel diminishes, the angle will slightly change even if the 7" dimension is rigorously maintained. It is nothing really significant, but for anyone who is a stickler for the angle being "just-so", the best approach is to measure the bevel angle directly and set the length of the slide arm accordingly.
     
  17. hockenbery

    hockenbery AAW Advisor Staff Member

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    Bill,
    You can grind the tip with your method but the wings will be off.
    Photo shows my result grinding an Ellsworth with two passes on your set up.
    The wing profile will be different and at a different angle. I put black marker on he bevel.
    The tool would be definitely usable if ground with your set up. I think you loose a little of the shoulder edge which make the shear cut work well.

    If I were 30 years younger I would send you the vector equations and rotation matrices to show the mathematical proof.

    A simple solution is to get a 3/4 inch square tube from lowes or home depot.
    Mount a wood block on it. ( cut vee in block and attach with a u bolt)
    Cut the block or glue on a piece so the top 4" down from the center of the wheel.
    Then glue on a little vee cut on the bandsaw.

    Don Geiger vertical solution is pure magic!

    Al
     

    Attached Files:

    Last edited: Nov 1, 2012
  18. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Well, Al, I feel you pain since I am not a spring chicken either. If you find that fountain of youth, let me know and I will do likewise. Perhaps then we could tirelessly slog through weighty math equations. :D

    Since, math and I are old buds (although we haven't visited each other in a while), I find comfort in its presence while even the thought of using math to solve problems gives my wife cold chills (despite the fact that she is a school teacher).

    You realize that I might be forced to drag my Wolverine out of the attic and use it again. ;) Maybe later today if I have nothing else to do, I may post some additional stuff about this.
     
    Last edited: Nov 1, 2012
  19. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Al, I decided to create a graphic that I thought might help visualize things. Since I am not into doing animations, a single drawing that shows the Wolverine set up being rotated into the Ellsworth fixture will have to suffice.

    While doing this, I had a thought that might explain the results that you got. So my question would be how did you set the Wolverine arm position? If my hunch is correct, I am guessing that you may have set it at 7 inches just as it would be done with the fixture that Ellsworth describes for setting the nose angle. If that is what you did, then that is the problem. Here is the drawing that I made that shows the jig orientation with respect to the grinding wheel as the Wolverine fixture is rotated into the same position as the Ellsworth fixture.

    Ellsworth-rotation-arrow.jpg

    The two things that the drawing attempts to show are that the distance from the center of the wheel to the pivot point of the jig does not change and the angle between gouge and wheel does not change.

    So, I need to reiterate that the length of the Wolverine arm from the face of the wheel is not seven inches -- it will depend on the height of the Wolverine with respect to the particular grinder being used. Rather than measuring a distance, my suggestion is to set the bevel angle to 60° using an angle gauge and then set the Wolverine arm to whatever it needs to be. Once you find out what it needs to be (on my Grinder, I think that it was about 5 7/16 inches, but since my Wolverine is now in the attic, I can't say for certain).

    Let me know if this clears up any misunderstanding or if you think that there is something else.
     
  20. hockenbery

    hockenbery AAW Advisor Staff Member

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    Bill,

    I set the arm to line up the bevel on the wheel.
    Your drawing assumes the pivot is a single point in the pocket corner.
    The pivot point in actually somewhere insides the jig rod maybe 3/16 shift in -x, + y from where the three Walls of the pocket meet.
    X<>Y

    I get the rotation of the Triangle to make it work you need to rotate the pocket too.

    With the set up you would have to angle the base of the woulverine pocket to make it the same.
    as it is the the bottom of the vee of the pocket is parallel to the floor and the back is perpendicular

    What you do is close but not the same.

    Al
     
    Last edited: Nov 2, 2012

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