Naural edge bowl from a crotch

Discussion in 'Tutorials and Tips' started by hockenbery, Jul 16, 2014.

  1. hockenbery

    hockenbery AAW Advisor Staff Member

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    Turning a crotch is fun and produces a heart shaped bowl with a highly figured bottom.
    I put a video from a demo I did in may on youtube.

    These are nice bowls for turners who have done 4-5 natural edge bowls without getting a catch. While best suited for intermediate and advanced beginners, the demo includes techniques that can be used on other turnings.
    Other than stopping the lathe a lot, this is how I turn a natural edge bowl.

    I use the Ellsworth gouge and a spindle gouge. I show push cut, roughing cut, pull cut, shear scrape, and Shear cut. I reccomend learning the shear cut from an experience turner. Attempting to learn the shear cut though trial and error can result in a massive catch destroying the work and causing serious injury. Our club has half a dozen members accomplished in the use of shear cut willing to coach those who want to learn it.

    One feature of the crotch bowls is lining up three high rims. I show how to do this in two steps rather than trial and error.

    I began the demo with a slides on prepping the blank.
    http://aaw.hockenbery.net/Natural edge crotch bowl.pdf

    The video:
    https://www.youtube.com/watch?v=8jVoI12Kfug&feature=youtube_gdata

    Demo summary. Mounting between centers. Lining up the three rims, initial roughing, the importance of always locking the head stock before using a movable headstock lathe, rough shaping with bevel riding push cut, final shaping with pull cut, cutting the tenon, relieving tension, finish turn the outside with pull cut and shear scrape, turning the inside with bevel riding push cut to remove wood and a shear cut for the finish cut. The shear cut is best learn hands on, attempting this cut by trial and error can result in catastrophic catches possibly causing injury. Reverse chucking, measuring bottom thickness,
     
    Last edited: Jul 16, 2014
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  2. Lawrence Tarnoff

    Lawrence Tarnoff

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    Audio is doubled

    This is a terrific video. I particularly appreciated the attention you paid to how the tool is presented to the turning. Starting about 28:00 into the video, however, the audio is mucked up.

    Larry
     
  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    Larry,

    Jan does a great job with the camera for our club.
    These are bowls I enjoy turning. I'm glad you enjoyed the video.

    Regarding the sound. There is a half minute or so that should have been cut.
    It is an unprofessional section - :) - Carl made a joke and I'm holding back a laugh almost.
    This demo was for my home club so we had several minutes of private jokes that don't make sense on the video.
    I cut 3 of them. Should have gotten this one too.

    Al
     
  4. John Altberg

    John Altberg

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    I just watched this video and learned a whole bunch. I would like to learn that shear cut on the inside of the bowl with the left wing of the gouge. It looks like it could go massively wrong in a hurry! Thanks for a great video, Al.
     
  5. hockenbery

    hockenbery AAW Advisor Staff Member

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    I suggest you find someone to work with hands-on for learning the shear cut.
    If you roll the tool too far you get a massive catch and blow up your bowl.
    Once you learn the cut it locks in like any bevel riding cut but the bevel is really short so it takes a finer feel.

    You don't really need the cut but is sure cuts down on sanding.

    Have fun and work safely,
    Al
     
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  6. Jerry Bailey

    Jerry Bailey

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    just noticed this thread, excellent video and definitely clears up a few things for me
    love the pdf for cutting the crotch with chainsaw, have a bunch of wood being delivered saturday and know there's a few pieces included
    Now I have perfect idea how to cut and prep blanks .....


    quick question, about 30 minutes in you stated turning roughly 1100 RPm
    I understand it depends on sizes of blank, but was that the speed you ran at most of roughing ?

    Thanks Al, excellent demonstration ..
     
  7. hockenbery

    hockenbery AAW Advisor Staff Member

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    One thing I often do in cutting the blanks is go for one good one.
    When I get a really nice crotch 8-10" diameter or larger I will cut 3/4" to one side of the centers and go for all the flame in one bowl rather than get two ok bowls.
    The blank with the pith will have the most feather and I put the pith in the chuck mount so I don't use feather grain in the chuck tenon.
    I plan the bowl so that all the pith is cut away when reverse chucked. The other blank can still make a heart shaped bowl but it won't have the dramatic feather.

    Smaller crotches 6" diameter I usually just cut in half for two bowls.

    There is no magic speed. That is a small 11" diameter blank with little height.
    Powermatic weighs 600-700 pounds it can run that fast with no vibration.
    I can't tell for sure but I probably started at a slower speed when I first started roughing.

    The same blank on a 200 pound lathe we go slower.
    A 16" blank I would be turning a lot slower.

    These blanks and bowls will always be unbalanced.
    The interrupted cut is cleaner and easier to make with a higher speed but Higher speed causes vibration and I don't want any vibration for the finished cuts.
    Speed is often a trade off. There is no need for crazy fast speed.

    I accept some vibration in the roughing because as I cut the bowl will become more balanced and vibration decreases.
    I never look at the rpm, I just sort of crank up the speed just below the vibration speed.
    In general I would usually be turning at lower speeds on a larger bowl.

    Have fun,
    Al
     
    Last edited: Aug 28, 2014
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  8. Jerry Bailey

    Jerry Bailey

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    Many thanks for the reply Al,
    So this is one time where using the pith is good .......... thanks for that :)
    like I said, have a truck load of wood coming, 4-5 different species, and I think the crotch wood will be Mesquite, that was a quite large tree
    One other tree was said to be over 40' tall , so will have plenty of wood and I too would rather get the 1 excellent blank too versus the 2 so-so ...

    lathe is 300 lbs, bolted to a 300lb. 8' cabinet , so not worried about vibrations here ;)

    You stated you removed point from drive center for mounting initially when balancing,
    I have the same option, but, that'll leave me with a roughly 3/8" - 1/2" open end, is that too big for this?
    I understand why the removal, just want to make sure mine isn't too big and won't hold the piece in place.

    I generally do larger pieces, 12-18" , so am accustomed to starting slower and working my way up as I progress, so no worries there.
    just never saw you adjusting speeds throughout the turning .......
    Loved the tip about turning over the blank and removing some of the interior to remove the stress, then flipping back over and finishing bottom
    haven't thought about that before but makes great sense.

    TIA
     
  9. hockenbery

    hockenbery AAW Advisor Staff Member

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    Just to be sure in the large bowl the pith is cut away when it is reverse chucked. The pith is left in the blank so it can be used in the chuck tenon to save most of the feather grain for the bowl. I do leave the pith in when I turn in the round crotches but these are relatively small

    .
    I use the ONEWAY center. The cup is 5/8” in diameter and it is ½” inside the cup.
    As long a the headstock and tailstock are locked in place the ONEWAY center holds great. Any cup center about the same size will work.
    Start with a small blank 8-10” diameter. In the demo I had to stop and lock the headstock because it was not locked tight enough.

    Start with an 8-10” blank. It will go quickly.

    This also balances the bowl more so you can increase the speed a bit for the finish cut on the outside.
     
    Last edited: Aug 28, 2014
  10. Jerry Bailey

    Jerry Bailey

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    Again, thanks for the reply
    have all info stored away, and will put it to good use

    still thinking about the flipping/removing stress, it'll work with different applications, and solves issues I've had in past
    mainly working with Cottonwood and some Walnut pieces, get outer bowl turned to shape, flip and do interior, then while drying(and turning) outer has lost it's shape/evenness
    Will start doing that process more often and should reduce a lot of my "double work" redoing/refining outsides :)

    and yessir, I figured 1st crotch turning would be smaller, maybe 10" at most, just to get hang of things.
     
  11. hockenbery

    hockenbery AAW Advisor Staff Member

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    Jerry,
    You are in a dry climate.

    Use a plant mister or other spray bottle to keep the wet wood wet.

    I use one on large hollow forms in Florida because the thin walled top of the piece will dry while I'm hollowing toward the base.

    Also when the bowl come off the lathe I will wash it in the sink. Just run clear water all over it.

    Then put it in a cardboard box with a block of wood to keep,it off the bottom of the box close the flaps for a day.
    Open one flap for a day,
    Open both flaps for a day,
    Put the bowl on a shelf for a day
    Then it is ready to sand and finish

    This is an insurance step to keep any bowls or hollow forms that may have a not too even wall thickness.
    Most will dry for me without the box but the box gives me peace of mind and it sure works for me.

    If I turn a bowl thicker than 1/4" wall thickness. I will put it in a grocery bag for a week or so.

    Let me know how you make out

    Al
     
    Last edited: Aug 30, 2014
  12. hockenbery

    hockenbery AAW Advisor Staff Member

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    If you have a spare three minutes this is a YouTube link in which I turn the outside of a natural edge bowl.
    It may encourage you to pursue the Ellsworth ground gouge.

    http://www.youtube.com/watch?v=qZ0fC5Rk6h4

    Natural edge bowls can be turned successfully with many tools. I have found the side ground gouge works best for me.

    The video is me working with the explanation dubbed in later.
    It shows the process with a brief explanation.
    In comparison, the crotch NE bowl video is a demonstration with much of the time spent explaining the process and showing details.

    I should point out I turn faster than most turners but not nearly as fast as the top turners out there.
    If you get an opportunity to see David Ellsworth demo a natural edge bowl take advantage of it.
    He spends about an hour turning a bowl and explaining all the steps in detail. Then he takes a few minutes and turns one at his natural speed.
    Gives everyone an "oh wow" moment to go with a great learning experience.


    Al
     
    Last edited: Oct 20, 2015
  13. Zach LaPerriere

    Zach LaPerriere

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    Thanks!

    Great video, Al. Much appreciated.
     
  14. Douglas Ladendorf

    Douglas Ladendorf

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    I enjoyed it as well. Thanks Al.

    Doug
     
  15. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Very nice, Al.

    It appears that at the beginning you are doing a push cut left handed. When you switch to a pull cut it appears that you change your hold to a right handed cut. I can reluctantly swap hands when necessary such as working on the headstock side of a turning, but I strongly prefer doing things right handed. Since you were working on the tailstock side, is there an advantage to the left handed push cut or is it personal preference?
     
  16. hockenbery

    hockenbery AAW Advisor Staff Member

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    First off the wood does not know which hands are where. As long as the business end of the tool is at the correct angles the cuts will be the same.

    The advantages for me with the right hand forward in the initial roughing with the bevel not riding are that the chips don't hit me and I am positioned well to see the roughing process take shape and to size the tenon ( I just cut an inch from the tail center which is 5/8" diameter always get close to a 2.5" tenon). I have trained myself to measure an inch by eye.

    The advantage of pull with the bevel riding is that it yields a very clean surface and almost always cuts the bark cleanly. Making it with the left hand forward. I am standing a bit above the rim and have a great view of the bowl's curve along the top horizon rim to foot.

    I don't consciously think about which hands so much as where I want to work on the bowl and how to position the cutting edge. The hands then decide how to put the tool on the wood. On a really big bowl I will do some of the pull cut standing at the tailstock side right hand forward so I don't have to reach around the bowl from the headstock side ( I can stay out of the line of fire)

    It took me a long time to get comfortable using either hand forward. I made myself use the right hand forward when I wasn't working on a finish cut and eventually I got confident to use it forward for finish cuts too. When I turn balls I turn the right side with the left hand forward and the left side with the right hand forward. The choice of hands is to see the curve. Last year for the first time ever I turned the left side of the ball better than the right side of the ball twice. Both time in demos.

    :) I blame turning the right side better on my left eye dominance which I blame on too much baseball. Couldn't have anything to do with being right handed. -:)
     
    Last edited: Oct 23, 2015
  17. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Thanks for clearing that up. Our mesquite wood here in Texas is pretty smart, but maybe I am giving it more credit for knowing what is going on that it deserves. I'll consult the post oak tree in the back yard to see what it has to say about this. :rolleyes:

    I figured that might be the case. I actually like the taste of shavings, but the bark tends to be a bit bitter. And I hate the taste of borers -- too astringent.

    My turning style is probably oddball because I frequently sweep around the entire bevel of the gouge going from pull to push cut in a single pass as the edge quickly becomes dull cutting dry mesquite and I am wanting to make a clean cut.

    My pull cut is more like a shear cut and I tend to cut with the tool handle really low. Because of that, my favorite tool rest is the ones that Steve Sinner makes. All the others don't allow me to drop the tool handle as low as I like.

    I attended an all day demo at our club by Craig Timmerman last Saturday and I was pleased that there is somebody besides myself who doesn't subscribe to this notion of only looking at the top profile to gauge the outside curvature. While I do frequently look at the "upper horizon", I am continually scanning everything that is going on ... looking at the quality of the cut, sharpness of the tool, lower horizon, and on and on.

    I'll use a right handed grip if I can, but I do force myself to turn left handed on the headstock side of turnings.

    I think that I have left eye dominance, but it is interesting that I do some things left handed. For example playing baseball/softball I batted and threw the ball left handed. I used a shotgun or rifle right handed and used most hand tools right handed although I can use a hammer or saw with equal ease in either hand. When I was in the first grade I initially wrote with my left hand until the teacher corrected that deviant behavior. :rolleyes:
     
    Last edited: Oct 23, 2015
  18. hu lowery

    hu lowery

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    well since you brought it up . . . .


    Bill,

    If you don't already know it, left handed people are indeed evil and deviant. The teacher might have saved you from being another charles manson! On the other hand, world leaders, artists, genius types, all more heavily represented in left handers than they should be! Maybe you need to step up to the plate.

    I swap hands pretty readily turning and some things. One reason is that it seems to me like the front hand is doing at least equally skilled work so why shouldn't it be the right hand? Never understood why I shouldn't use my right hand as the one bridging shooting billiards either. Casting reels, revolvers, both designed by lefties to begin with. As a right hander to get a right hand reel I buy a left hand reel! My brudda the lefty that does a lot right handed pointed that out.

    With a pretty hopelessly dumb left hand I used to deliberately use it for rough and heavy work until it became stronger than my dominant right hand. Figured the left hand ought to be good for something, I hold my beer right handed.

    Aside from other reasons, swapping hands I also usually swap turning positions also so that I dull both sides of the gouge instead of sharpening one side over and over when it has never touched wood. When it comes to steel I am very stingy!

    Hu
     
  19. hockenbery

    hockenbery AAW Advisor Staff Member

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    Bill,

    I look lots of places too. The horizon is where I see the curve. Behind the cut is where i see the surface. Often I want to see the tool role into bevel contact an pick up the cut in particular spot. Where people get into trouble is when they only look at the tool's tip.

    I sometimes lower the handle more in the pull cut. It is a trade off. When the wing edge is more vertical I get a cleaner cut but I don't turn the curve as well.

    Using all the cutting edge is a great way to have a sharp tool.
    When I hollow bowls I do the finish cut withnthe left wing and use the right wing to rough wood away.
    That keeps the finish side sharper longer

    Al
     

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