• January Turning Challenge: Thin-Stemmed Something! (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to Gabriel Hoff for "Spalted Beech Round Bottom Box" being selected as Turning of the Week for January 6, 2024 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

How to turn ovals?

S

squirrel

Joined
Sep 27, 2007
Messages
132
Likes
1
Location
Belgium
Hello,

it probably is old stuff for you guys but for me it is new.
Can somebody tell me wher I can find information about how to turn oval boxes?

Thanks!
Squirrel
 
turning ovals

Vicmark markets a machine that attaches to a lathe that lets you turn ovals. The one I saw at the last SWAT symposium had an asking price of 2500.00.
It was mounted on a Powermatic 3520b.How many did you say you wanted? You also need the articulated arm hollower at an additional 300.00.They probably have it on their website.Max
 
Simplest way would probably be to use a Rose Engine with an oval cam suited to the desired shape. Interior depth of the box and lid would be limited by access for the cutter. (Might need to mount on the bias for deep access.) Browse the forum and/or recent issues of American Woodturner for DIY Rose Engine plans. In addition to the oval shape, lots of other shapes are possible, as well as getting your feet wet in ornamental turning.

Less control over the final shape would be to turn a piece of green wood, cross-grain like a bowl, into a hollow cylinder. Then wait a day or two or three for it to become oval. The amount of oval eccentricity can't be predicted. Top and bottom will need to be cut to fit.

Joe
 
What Ralph (n7bsn) said. But at almost the same cost as a mustard monster, it could be out of reach. See "Lathes and Turning Techniques - The Best of Fine Woodworking" from Taunton Press; ISBN 1-56158-021-X, back of title page indicates library call numbers of "TT201.B43 1991" and "684.083-dc20." Possibly different system in Belgium. An article on page 52 describes the Old Schwamb Mill, with enough detail to design and build your own eccentric chuck, subject to your CAD or drafting abilities as well as mechanical skills. The article originally appeared in Fine Woodworking magazine (May 1986) 58:74-78. My post-it note indicates an episode of New Yankee Workshop re-run on 3 December 1998 on HGTV in USA. The article is silent on speed, except "considerably under 1000rpm," but my note says it "looked like about 100 rpm."

These accessories will only turn ovals, but I think both have adjustable eccentricity.

Joe
 
There's the circle that looks oval created when you turn a piece longer than it is wide. There's the oval you could make by turning a circular rear and interior with uncut wings and reducing them with drawknives/shaves and gouges. You can fool the eye fairly well with either alternative, but fitting a lid, as with a box, might be a time-consuming operation.
 
Oval Woodturning

David Springett's book "Adventures in Woodturning" I think shows you haw to make an oval turning jig from wood n stuff. It may be in another of his books as it's been a long time since I've read it.

I saw a commercially made oval chuck today at the Vicmarc booth of the trade show. $1999 show special .

Alan Lacer gave me a quick tour very nice, very quiet as the Springett model tends to be a bit noisy. But cheep......all the sweat equity you can afford.

Angelo
 
Hello,

I thought it must be possible to do it to change centerpoints by hand.
Just by using a bit of mathematics. The problem is how? I saw it once described in a book but I don't know where.
I just want to try out a couple of oval boxes and then it is not worth to buy an excentric chuck already.

Anyway I will have a look at the sites you mentioned.

Thanks a lot.
Squirrel
 
An approximate oval can be created by multi-axis turning. Similar to an isometric "oval." See Barbara Dill's articles on that topic in American Woodturner, Fall and Winter 2007 (Vol. 22, Nos. 3 &4).

Joe
 
I've had a Vicmarc VOD for about a year and a half. Woodworker's Emporium in Las Vegas has them (had one at the symposium). Rose engines and sliding plate chucks (based on a design by DaVinci) will only turn very small items, unless you can get a sliding plate machine made in the 1800's when they were quite the thing. I make my wife her hat blocks, and none of these would work for a 5 lb chunk of poplar. The VOD will, and I've turned oval bowls up to the limits of my Stubby with it. The VOD closely follows a design by Johannes Vollmer and has counter weights to balance the wood (and metal) that's being thrown about to let you make an oval. You can see a couple of photos of my setup on our website (http://www.abhats.com). One of my demonstrations is about how it works and I'll be at Tidewater Turners tomorrow night giving one.
 
This is definitely cheating, but I've done several "oval" bowls by first building a segmented bowl and then cutting it apart and re-joining it at the top edges. The first bowl should be taller that its diameter. It's conventional segmented, stacked, ring construction. If during the first bowl's construction, you create one ring with a bigger diameter, you can later carve feet. Here's an example:
 

Attachments

  • Oval Bowl low-res.jpg
    Oval Bowl low-res.jpg
    45.4 KB · Views: 35
tahoeturner said:
This is definitely cheating, but I've done several "oval" bowls by first building a segmented bowl and then cutting it apart and re-joining it at the top edges. The first bowl should be taller that its diameter. It's conventional segmented, stacked, ring construction. If during the first bowl's construction, you create one ring with a bigger diameter, you can later carve feet. Here's an example:
Click to expand...

That'd be a race-track "oval," Malcolm. Not a true ellipse. I once knew the mathematical term for the shape, but now long forgotten.

It'd be a more convincing fake if you hadn't run out of the yellow wood.😉

Joe
 
I have to respectfully disagree that you can only turn small objects using a sliding plate oval turning chuck.

I saw one that a guy made based on Springetts chuck he describes in the book posted above, and he was turning some pretty large stuff.

I've also seen the huge frames that were turned on the old ones at the Schwambe mill described above.

I've been wanting to build one, but the price of Springett's book (out of print) at $100 is kinda prohibitive...
 
Joe Greiner said:
That'd be a race-track "oval," Malcolm. Not a true ellipse. I once knew the mathematical term for the shape, but now long forgotten.

It'd be a more convincing fake if you hadn't run out of the yellow wood.😉

Joe
Click to expand...

Joe, I think if you turn the first bowl with a perfect half-oval shape, then the result of cutting it in half and joining it back together, should produce an oval. At least that's what I've tried to do with this shape.
 
tahoeturner said:
Joe, I think if you turn the first bowl with a perfect half-oval shape, then the result of cutting it in half and joining it back together, should produce an oval. At least that's what I've tried to do with this shape.
Click to expand...

Righto, Malcolm. My mistake. A deep half-ellipse, cut along the present rim. I'd still vote for yellow segments near the rim, though.😀

Joe
 
The sliding plate mechanism to turn oval things was invented by DaVinci - it really is that old. David Springett made one like it (he makes almost everything he uses) and has a very good DVD on using one, but this type mechanism has no counterbalance weight system. The Old Schwamb Mill in New England has a large sliding plate mechanism that has been used to turn oval picture frames for centuries, but they don't weigh much even though they are large in size, and they are turned very slowly. The difference with Johannes Volmer's mechanism is that it's belt driven and has counter balance weights. The Vicmarc version is rated for 5kg total weight (faceplate/chuck and wood) at maximum 'oval-ness' and reasonable rpm. No one should try spinning that amount of weight on a sliding plate version even slowly. Try reading Volmer's website and down-loadable pdf: http://www.volmer---ovaldrehen.de/englisch.htm and http://www.volmer---ovaldrehen.de/englisch.htm. There's some very interesting information in it, including a wonderful ivory oval turned goblet made in 1586 by a court turner.
 
waltben said:
The sliding plate mechanism to turn oval things was invented by DaVinci - it really is that old. ...
Click to expand...

Or older. Really

I've done a bunch of reading on DaVinci, and most real experts don't think he invented everything he drew. This gets obvious on some of his drawings, where it is obvious (if you try to build it) it just doesn't work.

A couple of the people that have studied such things firmly think that oval turning predates DaVinci, and that DaVinci either improved the methods, or maybe just drew them up

TTFN
Ralph
 
Ok... now you've done it. 😛 I'm going to have to find the site where I saw the guy using one of these oval chucks and what he was turning... :cool2:

I'll get back to you on this...
 
You must log in or register to reply here.
Back
Top