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How to use the One way easy coring system.

Discussion in 'Woodturning Discussion Forum' started by Breck Whitworth, Dec 26, 2017.

  1. Breck Whitworth

    Breck Whitworth

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    I hate to keep asking so many questions, but I would hate it more if I messed up a beautiful spalted wood block when coring because I didn't get the information straight in my head before starting. I bought the easy core system of bowl coring but the instructions are non existent other than the grainy video which was some help.
    Are the boards they talk about for depth measurements? I have my knife sets running dead center after a little back yard engineering. I need to know more information on coring the different size bowls compared to the depth I can expect. So imagine me an empty vessel of this type coring and those of you who use them please remember when you first started and anything that helped you will no doubt help me. Please don't assume I know anything about this system and go from there. Thanks ahead of time.
     
  2. Owen Lowe

    Owen Lowe

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    Breck,
    Each knife has a maximum depth because you just can’t position the base closer to the headstock than the upright supports allow. To arrive at the maximum depth for my knife sets, I placed a flat board perpendicular to the lathe bed so that I could position the base as close to the headstock as possible such that the knife at full swing just touched the board. Then I measured the distance between the board and the base and wrote this “zero depth” measure on the knife.

    The next step to using the measure is to establish some sort of reference for where the outside bottom of your bowl would be. For me, it changes depending on which chuck and jaw set I’m using. One of my methods is to mount the chuck and desired jaws to the lathe with no bowl attached and drop a line straight down to the ways where the face of the jaws lie. If I were to position the base distance from this line equal to the “zero depth” measure from above, then the thickness at the bottom of the bowl would be zero — and more funnel than bowl. Merely add the desired bowl thickness to the "zero depth" distance and the knife will leave that thickness.

    I believe the wood spacers in that old video — Oneway really needs to upgrade that video or take it down and link to one of the independently done YouTube videos out there — are a shortcut way to set the base distance from some standard reference point on the lathe, but they won’t work if the place where the outside bottom of the bowl changes distance from the headstock (due to different chucks/jaws/faceplates). You would need a full set of boards for each mounting combination for each set of knives.

    If my method needs a few pics to better get my words across, I’d be happy to snap a few.
     
    Last edited: Dec 26, 2017
  3. Glenn Lefley

    Glenn Lefley

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    Can you add pictures where possible, I'm in the same position as Breck. Thks.
     
  4. Owen Lowe

    Owen Lowe

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    Always square the coring base with the lathe bed; that will provide future measuring consistency. Here you can see the board sitting perpendicular to the bed. It doesn’t really matter what it’s against at the top as long as it is straight up and down.
    IMG_42791.jpg

    Keeping the base square to the bed, adjust the distance from the board so that as the knife swings to the maximum it barely skims the board’s face.
    IMG_42802.jpg

    Measure the distance from base to board. Here it’s just shy of 6.5”.
    IMG_42823.jpg

    Write the distance on the knife. This is the “zero thickness” distance. You never have to do this part of the set-up again — but you do have to do this with each differently sized set of knives.
    IMG_42834.jpg

    To set up the base for actually coring, drop a line straight down from wherever the outside bottom of the bowl will be. I consider the face of the jaws as the outside bottom for the way I work but it could be different if you like different mounting or foot profiles for your pieces. I placed a piece of tape on the bed just at the edge of the blade — and drew an arrow for clarity. This arrow point (and tape edge) represents the same distance in horizontal space as the jaw faces above it.
    IMG_42845.jpg

    Now set the base distance from the arrow/tape edge by adding the desired bottom thickness to the “zero depth” marked on the knife. In this case a 7” distance will yield a 1/2” bowl bottom (7” - 6.5” = 1/2”). This is the minimum thickness the knife will leave if the knife post is placed dead-center to the bowl; if it’s left or right of center (but still square to the lathe), the knife will leave greater depth but only by an eighth inch or so at the most.
    IMG_42866.jpg

    Hope that clarifies my first post. If not, don’t hesitate to ask.
     
    John Turpin likes this.
  5. John Spitters

    John Spitters

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    This is exactly what I have done. I zeroed out my knives and referenced how deep each knife will cut in relation to the front of the base clamping plate, this # is permanently written on the back side of each knife.
    Since I tend to not always using the same chuck and jaw setup when coring I’ll take my framing, square reference the front face of the jaws and transfer that measurement to the bedways of the lathe and mark it with a permanent marker on the bedways. (Not to worry this is easy enough to remove)
    Now by simply adding in the desired bottom thickness of my bowl I add this measurement to the measurement written on the back of the knife. This combined measurement is now laid out from the line written down on the bedways to the front face of my clamping plate.
    Note this works only when coring from largest to smallest.
    However it can also be used when wanting to core from smallest to largest by setting up for the largest coreout first then without moving the base clamping plate insert your smallest knife set first and work your way up to the largest set. This second method works but gives you little flexibility and limits the thickness of your cored out bowls.
     
  6. Owen Lowe

    Owen Lowe

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    What him /\ say! (shorter and sweeter compared to my diatribe!) Good point, John, on how the setup affects the small to large vs. large to small sequence. If you want flexibility going small>large, you have to add the multiple desired bottom thicknesses and the cutter kerf widths — it can get confusing unless you sketch it out. DAMHIKT! :confused::mad::oops:
     
  7. Richard Coers

    Richard Coers

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    Definitely don't make that block of spalted the first attempt!
     
  8. DON FRANK

    DON FRANK

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    I started doing the set up a little differently instead of using spacer boards etc. When I'm getting ready to core I place the cutter against the face of the bowl like Owens pic #1 and 2 except the cutter is touching the face of the bowl. I also use a square to make sure the base is perpendicular to the bed. Then I simply measure with a tape measure on the bowl blank to the depth that I'm wanting to cut. I doing so be sure to subtract the 1" +or- in extra thickness that you are allowing for if doing twice turned bowls. Then I measure over from the base of the camping plate that distance (towards the headstock) and put a piece of masking tape on the bed. Then loosen the clamping base, slide it over to the tape, re-square it and bolt it down. Of course you have to move the base right or left before clamping to determine where on the bowl that the cut will begin. This method is very quick and simple and pretty foolproof.
    The variables are whether you do an outside or inside tennon that your jaws are grabbing. I have gone exclusively to an outside tennon which makes the depth of the cut needed very simple. This allows me to clamp the jaws tight whereas if expanding the jaws you have to be careful not to crack the base of the bowl.
     
  9. Breck Whitworth

    Breck Whitworth

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    Owen I can't tell you how much you have helped me, the pictures are wonderful they make the written description much easier to visualize. So provided I use the same chuck and jaws these zero measurements will not change. Once I have added the bottom desired thickness to my zero measurement I will have my desired depth. Question: there seems to be a wide range of possible core diameters for each knife set. If you choose any of them will the depth still be determined by the zero + desired bottom thickness (+ or -) 1/8 or so depending on placement of Knife post being centered or not? Is there a better choice between using knife set 3 at it's widest diameter setting or Knife set 4 at a smaller diameter to get the same thing? I assume you choose the knife set with the depth you have to work with after the money bowl is marked. If not, please explain.

    One more question for those of you have and use this system. How do you store your knife sets and the fingers when not in use? Any pictures of how you store these might be just what I need as I try to figure out how to adjust my turning room to handle this new system so they are out of the way yet accessible when needed.
     
    Last edited: Dec 26, 2017
  10. John Spitters

    John Spitters

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    I hope this link works http://www.woodturnersunlimited.com/forum/viewtopic.php?t=4865 This is how I store my system, you will need to scroll partway down through the thread to see my setup.
     
  11. Glenn Lefley

    Glenn Lefley

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    Am I right to say going from a smaller knife max depth to next larger knife same diameter cut you get a different depth bowl from cut? Are the curves on the knifes actual radius of circles? If they are ,does anyone know what the radius is of each size of knife?
     
  12. Breck Whitworth

    Breck Whitworth

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    Glenn the guy from oneway gave me this answer for the same question I asked him, maybe you can do a better job at understanding what he was saying than I did. "The maximum depth is the nominal diameter of the knife divided by 2 minus 1 inch. " I don't think he answered my question but if he did I didn't quite figure it out. I think this is just the depths each knife cuts at maximum.
     
    Last edited: Dec 27, 2017
  13. Breck Whitworth

    Breck Whitworth

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  14. Owen Lowe

    Owen Lowe

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    Your second question first: I store the knife sets in a cabinet. Not great and takes room but the different knives do kinda nest together when their arcs are in the air.

    It took some noodling to get my mind wrapped around why one should choose one knife over another. I needed to draw it out to get an understanding of the differences. In the drawing, the red, orange, and yellow arcs represent the #4, #3, and #2 knife sets (I don’t own the #1). The grey hemisphere is a wood blank and the dotted blue hemisphere inside that is the cut line that would yield 10% wall thickness (the wood’s center line is also shown by a dotted blue line). Look to the center and bottom half of the drawings to see what my words are referring to.

    Easy-Core3.jpg
    In this first illustration above, the desired bottom thickness is not possible with yellow #2 knife because the wood will hit the knife support tube before the depth is achieved — even though the arc at the beginning is perfect.

    Easy-Core2.jpg

    In this second illustration above, the desired bottom thickness is possible with orange #3 knife but the coring base needs to be moved away from you for the beginning of the orange arc to fall in the right place. This movement changes where the knife arc intersects the desired cut line but the difference is only about 1/8” thicker than needed at the bottom. However, note the space between the dotted arc and the solid orange arc — this represents a portion of the wall being thicker than necessary. This is because the center point for the bowl’s hemisphere can not be located at the center point of the knives' arcs.

    Easy-Core1.jpg

    In this last illustration above, the desired bottom thickness is possible with red #4 knife but the coring base needs to be moved far away from you for the beginning of the red arc to fall in the right place. Like knife #3 above this movement changes where the knife arc intersects the desired bottom center line and the difference is about 1/4” thicker than needed at the bottom. Now compare the space between the dotted arc and the solid red arc — this portion of the wall is substantially thicker than desired.

    You could adjust the placement of the larger knife to cut the beginning of the arc and intersect the bottom center but you wouldn’t really know how far toward the headstock to move the coring base and it still won’t follow any closer to the desired arc than the #3 knife would.

    Through all of this I believe the answer to which knife is the best choice is to go with the smallest knife whose depth of cut will reach as deeply as you want. Then adjust the base toward or away from you to get the beginning of the cut to yield the entry wall thickness.

    Thank you for asking the question because it helped me visualize what is happening and how that has jibed with my experiences. I believe I’ve chosen too large of a knife on more than one occasion because I’ve ended up with much thicker walls than I expected.
     
    Last edited: Dec 27, 2017
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  15. John Turpin

    John Turpin

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    That analysis was very helpful, Owen. Thanks for such a thoughtful reply.
     
  16. Breck Whitworth

    Breck Whitworth

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    Owen, wow you should have been a teacher that was a complex answer made very simple with your ability to provide a visual explanation to back it up. Thank you more than you will know for finally giving me a better understanding on these knife sets.
     
  17. Breck Whitworth

    Breck Whitworth

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    I agree Richard!
     
  18. John Spitters

    John Spitters

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    Owen, great illustration of how the use of each knife will have an effect on what the final outcome will be. By moving the center of your arc away from the bowl blank/block, along with also moving the arc center to either left or right of center.
    For myself I’ve always understood this but it’s good to see the results in a diagram such as what you have shown here.
     
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  19. Owen Lowe

    Owen Lowe

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    Thanks Breck. In my real life I’m an instructional assistant teaching reading with kindergarteners through 5th graders. A touch of 3rd grade math is thrown into my day for good measure. The college courses I took on teaching math emphasized doing visual representations for problems and that method really appeals to me. I’ve enjoyed replying to your question!
     
  20. Breck Whitworth

    Breck Whitworth

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    That doesn't surprise me having been a high school science teacher for 30+ years I can usually recognize another teacher or at least those who would have made a good one. Thanks again
     
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