Pull Cut ( aka peeling cut) with the side ground gouge

Discussion in 'Tutorials and Tips' started by hockenbery, Oct 31, 2013.

  1. hockenbery

    hockenbery AAW Advisor Staff Member

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    This is the most effective finishing cut I have found for interrupted surfaces such as outside of natural edge bowls or multi center spindles. It is a cut that is easily mastered on spindles but requires a basic level of tool control to be used successfully on bowls. if you are trying to learn it, my suggestion would be to practice on spindles and then practice off center spindles.

    I posted a video on YouTube that I cobbled together from a couple of demonstrations and some clips from turning a natural edge bowl.
    The video gives an overview of what the pull cut is. It is along way from being an instructional video.
    I hope other turners that use this cut will offer additional comments on how to do it effectively.
    You tube link
    http://youtu.be/OwLnJVLqerM

    The cut is done with the wing being "pulled" ( or pushed ) over the wood in the direction of the handle. The nose of the gouge is always out of the wood, trailing the cut( it is the nose that is being "pulled" behind the cut). If the nose contacts the wood a catch is likely. The tool is held with the wing at about a 45 degree angle to the wood rotation flute at 12 o'clock. The tool is rolled left or right until the cutting edge of the wing contacts the surface and begins to cut and peel the wood away much like peeling an apple with a knife.

    This cut produces a very clean surface and the tool handle can be dropped to make a cleaner cut with a steeper angle of the wing to the wood. I use this cut on problems woods that are not cutting cleanly with the push cuts. I also use this cut on the outside of natural edge bowls and it produces a clean cut on the bark most of the time. Using it on a the interrupted surface requires a light touch. ( variations of this cut include a roughing cut with the bevel not riding and one with the tool parallel to the floor on the tool rest).

    The wing of the gouge must be properly sharpened with a radius curve like the Ellsworth grind or almost flat. Any dip and it will be difficult or impossible to use in the pull cut. I use this cut on interrupted surfaces, platter faces, and problem woods where I'm getting some tear out with push cuts. The video is not a teaching video but the demo clips give some basics on how to do the cut.

    Al
     
    Last edited: Oct 31, 2013
  2. Dale Miner

    Dale Miner

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    A cut that requires a bit to learn, but worth the effort.
     
  3. robo hippy

    robo hippy

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    Well, a cut I have done, but not one I use. From looking at the video clip once, the only difference I can see between push and pull is where your body is. I am curious, some times it looks like you are rubbing the bevel, and some times not. Which is it, or is it both?

    robo hippy
     
  4. hockenbery

    hockenbery AAW Advisor Staff Member

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    The bevel is always floating over the wood like you would have knife peeling.
    Bevel is always rubbing very lightly except on the air in the interrupted cut where it needs to hold it's spot for the wood coming round.
    On tight curves the bevel rubbing becomes very small.

    The cuts are the same.
    When the tip of the gouge trails the wing through the cut I call it a pull cut.
    Body position does dictate whether I push the " pull cut" or pull the " pull cut".
    The point I was trying to make is both are "pull cuts" as long as the wing is in the same orientation.
    I choose where to stand based on where I can see the curve, staying out of the "line of fire", and where the chips are going.....

    I only use the pull cut on cut rim bowls and hollow forms if I'm getting tear out with the bevel riding push cut leading with the nose of the gouge, because I can shear scrape these and get the same quality of surface.

    On the interrupted cut of the natural edge bowl I get a much cleaner cut with the pull cut than I get with a bevel riding push cut. And a much cleaner cut on the bark.

    Al
     
    Last edited: Nov 1, 2013
  5. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I don't think that it is anything new -- that is how I have always made finishing cuts. I don't remember where I learned it, but it probably was from somebody in my club. I do agree that it generally leaves a very nice surface.
     
  6. hockenbery

    hockenbery AAW Advisor Staff Member

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    Its been around a long time. I first saw it done 20 years ago.
    Any tips on using it?

    It is one of the 6 cuts frequently made with the side ground gouge.

    Basic classes usually teach the bevel riding push cut, scrape, and shear scrape.
    These are the ones I usually use on cut rim bowls after the roughing cut.

    Advanced classes often include the
    Pull cut, shear cut, and roughing cut with the bevel not ridding.
     
    Last edited: Nov 2, 2013
  7. robo hippy

    robo hippy

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    Well, for my finish cuts, I mostly hold the gouge level and push. I prefer a more open flute, and a more rounded nose, and the gouge is rolled over almost all the way on its side. I cut more with the nose and less with the wing. I do rub the bevel, but always come back to clean up any tool marks with a shear scrape, using a big heavy swept back scraper. It is just easier for me.

    When I hear 'peeling' cut, I think of a skew on a spindle piece where you raise the handle to where it starts peeling off the wood. Found I can do the same cut with a more blunt nose/minimal sweep scraper.

    robo hippy
     
  8. dbonertz

    dbonertz

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    Al,

    How are differentiating the pull cut versus a shear cut?
     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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    To me, the shear cut is one type of pull cut with the handle dropped down low and rolled over so that the cut if farther up the wing. The shear scrape is similar except that the tool is rolled over much farther so that the top wing is almost touching the wood.

    Al, I don't think that I can add anything new. I misunderstood the original post referring to the video as being something relatively new. I should have noticed that this is the "How to" forum.
     
  10. hockenbery

    hockenbery AAW Advisor Staff Member

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    The shear cut I was taught is made with the gouge level and the flute at about 12 o'clock. The cut is made on the leading edge of the wing just off the nose.
    This is definitely an intermediate level cut. It is great on the inside of bowls. On cut rim bowls I start it below the rim and on natural edge bowls I start it at the rim.
    It takes a small cut.
    What makes this cut hard for some to master, is the tool must be held loosely so the gouge can follow the curvature of the bowl. Holding it tight pulls the gouge into a catch.

    If you have seen Trent Bosch turn bowls using his asymmetrically ground finishing gouge. He does a shear cut on the outside with the traditional ground side and a shear on the inside with the side ground side. He uses this tool on his bowl video too.


    Also like Bill said above. If the pull cut is made with gouge held vertical it Puts the wing in in a shear cut position rather than the peeling cut it makes when the gouge is at about a 45 degree angle from vertical. When too vertical it is easy to get lots of little lines.

    Al
     
    Last edited: Nov 3, 2013
  11. robo hippy

    robo hippy

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    Sheer vs shear vs scrape vs shear scrape....

    I get a kick out of Lyle Jamison. I was asking him about his 'sheer' cut. Sheer as in the night gown you want the missus to wear, meaning very light and delicate? No, no, no, sheer like the face of a cliff.... Oh, I get it. I always went with shear as in wind shear, from my days as a hang glider pilot, where on the inside of a thermal, the air is going up, and on the outside the air is going down, so more in opposite directions as in the cutting edge of the tool is shearing off in one direction, while the wood rotates in the other direction. Mostly it means the cutting edge is at a more vertical angle to the wood rotation, and the higher the angle, the easier the wood cuts. I compare it to driving over speed bumps. If you hit them square on, it can be a big bump. If you hit them at a 45 degree angle, you still get a bump but it is a lot less. If you hit them at more of an angle the bump is a lot less. Mostly a shear angle cut is better at gently cutting under the wood and lifting the wood off as you cut.

    So, a scraping cut: with a scraper, pretty easy, the scraper is flat on the tool rest, and the cutting edge is 90 degrees to the rotation of the wood. With a gouge, you would be holding it more level, with the flutes rolled all the way over on the side (open and closed flute confuses me, closed is a steep V flute, and open is a C, U, or ( flute). The only time a scraping cut is a good clean up and finish cut is if you are cutting end grain. Other than that, it is a very rough cut for heavy stock removal, and shaping.

    Shear cuts is done several ways. Most of the time with a gouge, you drop the handle, roll the gouge flutes on the side, and cut more with the wings. Most of the time, this puts the wings at 45 or so degrees to the rotation of the wood. The more sweep you have to your gouge nose, the higher of a shear angle you can get, and the more you can drop the handle. Shear angle can also go higher if the handle leads the cut rather than the handle being more in line with the rotation.

    If you hold the gouge more level, there are 3 different ways to get a shear cut. Some cut with the flutes more up/vertical. The bottom of the flute is cutting more in a scraping action, and as you get higher on the wing, the wing has more of a shear action. This type of cut is used a lot, especially on the inside of a bowl where the lathe bed, tool rest, and ways of the lathe prevent you from dropping the handle. Problem with this cut is that if you get up on the wing a tiny bit too much, the tool is unbalanced, and the wing will catch. If you roll it a bit more on the side, you are cutting more with the nose, but since it is rolled over, you can not get on the high side of the gouge, and the tool stays more balanced, so risk of a catch is greatly reduced. I prefer a more open fluted tool, and hold my tools more level. The Thompson Fluteless gouge is one of my favorites for this. The major advantage to the more open flutes and less pointy nose, is that they have a much bigger sweet spot, especially when compared to a V flute. You have a larger cutting surface to use and it stays sharp longer.

    I may explain this better in my video clip on fluteless gouges on You Tube. Type in robo hippy or fluteless gouges and it comes up.

    http://www.youtube.com/watch?v=suRxCxdMn4k

    Shear scrape generally means you are doing a shear cut without rubbing the bevel. I have no idea why it is called a scrape. Well, at least according to my definitions, where scrape is more about cutting edge relative to wood rotation, and bevel rubbing has nothing to do with it.

    robo hippy
     
    Last edited: Nov 3, 2013
  12. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Shear, as in a pair of shears or shearing sheep with an instrument that slices the wool. Do you suspect that Lyle was trying to pull the wool over your eyes ... ask him what does woodturning have in common with a vertical cliff? :D We know what he is really thinking.

    But, it is interesting that a sheer cliff is responsible for creating wind shear. Sheer coincidence? Shear-ly not!
     
  13. robo hippy

    robo hippy

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    Well, Bill, actually a cliff does not create a wind shear. It generates upward velocity as compared to laminar or horizontal flow. If you get on the down wind side, there can be huge rotors in the wind as in tumbling circular patterns. Very dangerous.

    robo hippy
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

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    OK, I don't believe in flying anything without a motor to make its own wind. Once, many many years ago we flew up to Colorado and were sitting in a cafe in Telluride (long before it was "discovered" and ruined by the rich and famous) eating hamburgers and watching some folks in hang gliders having fun catching thermals off the opposite cliff in the canyon. Nice thermals are what you would expect in "hang gliding weather" conditions. As you point out, a wind shear is a different sort of animal in behavior, but wind shear certainly is associated with high cliffs (or other mountainous terrain) when you add high winds to this type of terrain.

    My first real world flight experience with meteorological wind shear occurred about two weeks before completing my commercial pilot license training. I had the opportunity to fly through tropical storm Danielle where I became intimate with some real-world wind shear. It was interesting -- only me and my laundryman knew the full story of HOW interesting.

    And, I do know about rotors. They are much nicer when you are standing on the ground looking at them. And, airflow is never laminar in the vicinity of wind shear despite what you may have been told.
     
    Last edited: Nov 3, 2013
  15. robo hippy

    robo hippy

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    I never flew Telluride. I do remember the launch site was just under 12,000 feet so oxygen was not required. They were getting up to 20,000 ft. in thermals, and some did not remember all of their flight. They are smarter now. There are some pretty strong wind shears with the thunder heads there. Top out at 60,000 or so, and what goes up has to come down. That is why the hail is so big out there. I never got into motors. Just didn't like the noise. Much more maintenance also. Now I am a ground hog, but still get twitchy on good thermal days...... Sigh!

    robo hippy
     
  16. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I am a ground hog too. Aircraft ownership and flying got a little too rich for my blood. We were lucky that one of our partners was also an AI which made maintenance much less costly than it otherwise would have been.

    I believe your story about not remembering all of the flight at high altitudes. I went through hypoxia training at Carswell AFB as part of a joint military/civil aviation pilot training program. The climax of the program was going into the altitude chamber. Military pilots were taken up to a pressure altitude of 40,000 feet, but civilian pilots were only taken up to 25,000 feet pressure altitude. In the post test debriefing we got to see the results of how our brain function decreased dramatically.

    I suppose that you have heard that the prop on the front of a plane isn't there to propel the plane. No, its only purpose is to serve as a fan to keep the pilot cool. It's true! If you don't believe it, then just turn it off and watch the pilot sweat. :D

    Old aviation jokes never die.
     

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