Results 1 to 14 of 14

Thread: Turning an oval bowl?

  1. Turning an oval bowl?

    After many years of building furniture, I am screwing around with turning bowls, which I have concluded is the world's Second Oldest Profession.

    Last night I saw what appeared to be a turned oval bowl. For the life of me, I can't figure out how the heck a guy would do that without some fancy-dancy machine attachment gizmo. It even had the bark left on the edges.

    If you want to make a bed lemme know, but in the meantime, what's up with the oval bowl deal?

    Thanks in advance.
    Vietnam Vet With No Apologies

  2. #2
    It's an optical illusion that occurs when you turn a natural edge bowl. The curve of the bark makes the turning look like an oval but if you extended the sides of the piece up it would be round or close to it at least.

    The only other suggestion is that the piece was turned wet and the bowl shrunk more across the grain than it did with the length of the grain. If I remember correctly from my reading, you get about 4 times the movement across the grain than you do lengthwise depending on the species of wood and the moisture content so you'll get an oval after the bowl dries.
    Last edited by Raymond Overman; 12-07-2007 at 11:49 AM.
    Raymond Overman
    Happiness is a warm chainsaw

    "Do not wait, the time will never be just right. Start where you stand, and work with whatever tools you may have at your command. Better tools will be found as you go along." Napolean Hill

  3. #3
    HI

    Check out this site. http://www.volmer---ovaldrehen.de/englisch.htm

    Vicmark now make and sell the chuck. http://www.vicmarc.com/default.asp?contentID=549

    john

  4. #4
    I got to see the Vicmark oval turning thing up in Portland, and it is very interesting, as well as expensive. If you turn wet wood to finish thickness, and let it dry, it will go oval, almost no shrinking long grain, but quite a bit cross grain, just like boards. Of course, some woods warp more than others, and if you harvest and turn when the sap is running, you will get more warping than you will get if you harvest when the sap is down. As said before, natural edge bowls are a bit of an illusion, but if turned green, they will warp also.
    robo hippy

  5. #5
    Join Date
    Mar 2005
    Location
    Anaheim, California
    Posts
    4,910
    I suppose it comes down to exactly what you mean when you say "oval bowl": it is trivial (using standard lathe tools) to make a bowl that is oval from the top view. OTOH, making that same bowl so that the rim is a flat ellipse (i.e. it looks like a standard bowl from a side view) takes some serious hardware and ingenuity. (Or a big bandsaw, but that's cheating. )

    Or just work with ceramics, but that's a different forum.
    Yoga class makes me feel like a total stud, mostly because I'm about as flexible as a 2x4.
    "Design"? Possibly. "Intelligent"? Sure doesn't look like it from this angle.
    We used to be hunter gatherers. Now we're shopper borrowers.
    The three most important words in the English language: "Front Towards Enemy".
    The world makes a lot more sense when you remember that Butthead was the smart one.
    You can never be too rich, too thin, or have too much ammo.

  6. #6
    Join Date
    Dec 2006
    Location
    Tucson
    Posts
    4,973
    Blog Entries
    1
    One way to do this is to turn a deep bowl then split it from top to bottom then glue what was the 2 top 1/2s together. This is popular with segmenting.
    What you listen to is your business....what you hear is ours.

  7. #7
    Join Date
    Mar 2005
    Location
    Anaheim, California
    Posts
    4,910
    Quote Originally Posted by Bill Wyko View Post
    One way to do this is to turn a deep bowl then split it from top to bottom then glue what was the 2 top 1/2s together. This is popular with segmenting.
    (scratches head) How do you put a foot on it? (Other than the obvious, "I don't.")
    Yoga class makes me feel like a total stud, mostly because I'm about as flexible as a 2x4.
    "Design"? Possibly. "Intelligent"? Sure doesn't look like it from this angle.
    We used to be hunter gatherers. Now we're shopper borrowers.
    The three most important words in the English language: "Front Towards Enemy".
    The world makes a lot more sense when you remember that Butthead was the smart one.
    You can never be too rich, too thin, or have too much ammo.

  8. #8
    Join Date
    Dec 2006
    Location
    Tucson
    Posts
    4,973
    Blog Entries
    1
    Turn it with a thick band then chuck it to the now oval face and turn it sideways. Then the left over is trimmed down by hand.
    What you listen to is your business....what you hear is ours.

  9. What I saw was a bowl, if you look at it from the top, that was about 4" x 6" oval.

    Sorry I didn't describe it well.
    Vietnam Vet With No Apologies

  10. #10
    Join Date
    Dec 2006
    Location
    Tucson
    Posts
    4,973
    Blog Entries
    1
    The method I was refering to is in Malcolm Tibbets book on segmented turning. Another way to add to your knowledge of the art. I do like that vicmarc chuck as well.
    What you listen to is your business....what you hear is ours.

  11. #11
    Join Date
    Mar 2005
    Location
    Anaheim, California
    Posts
    4,910
    Quote Originally Posted by Bill Wyko View Post
    The method I was refering to is in Malcolm Tibbets book on segmented turning. Another way to add to your knowledge of the art.
    I've got that book...even read it . But the only things I remember from the "cut-and-paste" section were those ribbon pieces of his that make my head hurt to look at.
    Yoga class makes me feel like a total stud, mostly because I'm about as flexible as a 2x4.
    "Design"? Possibly. "Intelligent"? Sure doesn't look like it from this angle.
    We used to be hunter gatherers. Now we're shopper borrowers.
    The three most important words in the English language: "Front Towards Enemy".
    The world makes a lot more sense when you remember that Butthead was the smart one.
    You can never be too rich, too thin, or have too much ammo.

  12. #12
    There are several ways to skin that cat!

    Now, if the bowl is a true oval and the rim is flat with bark on it (natural edge), the next question in my mind is "what shape is the foot?"

    If it was turned on a chuck designed to do ovals and done at the same time as the bowl itself, the foot was probably done the same way and is oval. Green turned self-ovalling bowls won't react like that. Green bowls warp is overemphasized because of the empty middle of the bowl; it's not so apparent on the whole chunk of wood.

    I agree with Ray's thoughts, but not his math. I don't think the ratio is 4 to 1. I think it's usually 5:4 or 6:4 (3:2). The 3:2 or 6:4 (same ratio) would produce the 4x6 oval someone was talking about. That ratio is easily found by researching "lumber shrinkage ratio" in Google. Since we all wear our safety eye protection, should we going to Goggle instead of Google??

    Back to business here... If the foot is circular or really close to circular, and the bark is still on there, that says to me that it was turned as green. It was turned to the desired wall thickness and allowed or encouraged to oval to the shape you saw. The larger the diameter of the tree, the flatter the top edge of the bowl would be. If the trunk was 30" diameter, that would make a 90"+ circumference, and a 5" circle would be a really small portion of that 90" circumference, thus pretty darned flat!
    Dean Thomas
    KCMO

  13. #13
    For the REAL oval turning, and not the traditional optical effect of some natural edge bowls, you have to use a special "chuk"
    This was already in use back in the 18th century.
    Nowadays you can buy these devices (rather expensive)
    From those I tried, the smoothest is the oval device produced by Vicmarc.

  14. #14
    Join Date
    Nov 2006
    Location
    Tallahassee FL USA
    Posts
    291
    A Rose Engine with an elliptical cam can also do it; other shapes also possible. Not quite the same as "Oval Turning," and there'd be some hand or power sanding needed after the cutter(s) have done their duty.

    Joe

Similar Threads

  1. Bowl Turning Video
    By Julie Tanner in forum Turner's Forum
    Replies: 0
    Last Post: 10-27-2007, 1:45 PM
  2. Bowl turning - rotating head stock or off the end of the bed?
    By Chip Sutherland in forum Turner's Forum
    Replies: 6
    Last Post: 11-21-2005, 12:45 PM
  3. Turning Bowl Bottom
    By Glenn Hodges in forum Turner's Forum
    Replies: 13
    Last Post: 05-27-2005, 11:03 AM
  4. Review: Bill Grumbine's Bowl Turning Video
    By Rod Peterson in forum Turner's Forum
    Replies: 12
    Last Post: 02-16-2005, 6:29 PM
  5. Chatter/vibration in bowl turning
    By Greg Wandless in forum General Woodworking and Power Tools
    Replies: 5
    Last Post: 08-03-2004, 12:39 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •