Making an Oval Questions.....

Re: Making an Oval Questions.....

Bill Tindall, E.Tn.

Draw, cut out on band saw or saber saw, spoke shave/block plane/hand plane/fair with some sand paper on a block. Can be done in less time than it takes to think about some "easier" way. I have found a #4 hand plane handier for edges like this than the traditional spoke shave.

Re: Making an Oval Questions.....

John McGaw

I've tried the nails and string method but realized that there will always be some inaccuracy no matter how careful I am. I finally settled on a techie way -- draw what I want in a drawing/painting/drafting program (I've used several) and then print it out full-sized. Sometimes the printing was on single sheets, sometimes on multiples, and sometimes from a big printer an Kinko's. In each case I used contact cement to fasten the pattern to fiberboard which was then cut out and refined on the drum sander. This method has served for 15+ years and I've yet to find an easier or more accurate one. Of course if someone wants to buy me a large CNC machine to try out...

Thinking......

Barry Irby

I think you are correct.....

I need to make three (walnut?) ovals. I could make a pattern out of fiberboard and then pattern route the three. It could even be a half pattern.

I have a friend who could.....

Barry Irby

print the pattern for me. He has AutoCad. Wonder if KinKo could print one full sized from his file?

Re: Making an Oval Questions..... *LINK*

Dick Coers

Purchased fixture, but not difficult to make.


http://www.leevalley.com/us/newsletters/Woodworking/4/6/article1.htm

Re: I have a friend who could.....

AZ in Colorado Springs

Kinko's can print pretty large. As for copying, I've used them for

1) my son wanted a practice rifle for the drill team. He found a photo of one, and I had them enlarge it to the length we needed. Then used it as a pattern to cut it out of dimensional lumber, and

2) I made a doll cradle from scratch, making it up as I went along. When complete I didn't feel like drawing up a plan, so I disassembled the cradle and took the parts to Kinko's and got photo copies of each part. Much easier. They charge by the square foot.

The "two nails and string" method will make an ellipse -- which may or may not be the "oval" you have in mind.

Re: Making an Oval Questions.....

William Duffield

I am guessing, since it is a table top and shelves, that your oval is aesthetic, as opposed to being there for some technical reason. I also don't know how you could tell from a photograph whether the original had an oval top or an ellipsoidal top, and I don't think your customer could tell either. Therefore, an approximation, using a method such as Bill describes should work just fine. There are lots of explanations on the web and in books on methods to lay out an oval with ruler and compass. There are also several methods to lay out an ellipse with common drafting tools. If you really think you need a close approximation of an ellipse, you can build an ellipsograph like in the Lee Valley article or tell a computer to calculate one for you and print it out on paper. Either one large sheet or several smaller sheets, tiled, work. Most technical graphics programs have the capability to print registration marks at the corners of each sheet of paper, to facilitate aligning them. I use 3M Super 77 spray adhesive to stick the paper patterns to the wood.

OK, Everybody..What's the difference between

Barry Irby

An Oval and an Ellipse?

William is correct, I have only seen a picture and assume my son and DIL have only seen a picture also. So I am designing as we go.

The difference

John in NM

An oval generally does not have a formula. Put succinctly, its what you get by eyeballin' it.

An ellipse has a specific formula that can be defined and followed to repeat the pattern and to change its size or shape.

I've seen a router jig years ago (similar to the one in Dick's post) that made an ellipse. I think it was in an old old Rockler catalog, before they were Rockler.... can't remember what company they were then.

How I'd do it

Ellis Walentine

Ellipses are one of my favorite subjects. First, a word about true ellipses: They are pure geometric forms that can be described by a formula. Our eyes are very sensitive to whether or not we're looking at a true ellipse, so if you're going to make one, make it as perfect as possible (unless it doesn't matter to your customer). "Ovals" may or may not be elliptical; the term is used loosely to describe various non-elliptical shapes and approximations.

For one-off use on ellipses in the size range you mentioned, I'd probably make a simple "bulls**t grinder"-type ellispe jig for your router. Here's one from PopWood:

http://bit.ly/2wTbuPm

This type of jig is simpler to make and more accurate than templates created by the string method.

If you're going to do a lot of ellipse work and want the ability to rout or draw perfect ellipses from a few inches to 9 feet or more in length, consider making a jig like we created for a magazine article in 1993 (yikes!):

http://bit.ly/2fxwdAE

This article shows a cheval mirror I made with the jig and elsewhere in the issue you can find the plans for the jig itself. If you ever decide to built it, let me know and I'll send you a couple tips.

Absent a jig, you could draw an oval and make yourself a set of tiled printouts to tape to your blank for cutting. Alternately, you could make a template of one-quarter of your ellipse, fair it as well as you can with spokeshaves and files, ant then use it to template-rout a half or full oval. This is fussy work, time consuming and probably will end up with flats and bumps that will detract visually from the finished appearance.

Ellis

Re: The difference

Yonak

I believe an oval is an extended circle .. each rounded end is drawn with a single focus, the focii being separated by some distance.

An ellipse is a specific geometric shape. It's the shape of a circle viewed on an angle (such as looking at the top of a glass from various angles).

In my opinion, an ellipse is a much more pleasing shape to look at, being a natural shape.

Re: Making an Oval Questions.....

Mike Jurnigan in Zuni

Barry,

I have two of the BS grinders that Ellis mentioned above if you would like to borrow. One is home made out of wood and a little light weight. I have one that is machine shop made out of heavy aluminum plate. I did a coffee table with that one out of white oak. Send me an e-mail and I will get it to you.

Mike

If you need a true ellipse.

Gary Smyth

I don't know what size you plan. However, a Omicron Ellipsograph might be found. This was a staple for the old school graphics and even the astronomy/rocket industry. The pictured one is made for the drafting table. But much larger ones were made. The pictured one was designed to hold a extension beam (with cutter or pen) and the max size was 12" long for this model 17. Others could (unadapted)do a 36" long ellipse. They could be scaled up with a proper beam. This one was used for portrait frames and mats.

Re: Making an Oval Questions.....

John Pappas

Another way:

http://zo-d.com/stuff/squares-and-measuring/how-to-use-a-framing-square-to-draw-an-ellipse.html

Re: Making an Oval Questions..... *LINK*

William Duffield

If you want to watch an old ellipsograph in operation, check out Norm Abram's tour of the Old Schwamb Mill in Arlington Massachusetts on the New Yankee Workshop Season 7 Episode 7. The lathe is for turning elliptical picture frames with fancy moldings. I don't think I would want to be in the same building when they turned it on.


NYW S07E07

Re: Making an Oval Questions.....

Clint Searl

I use a spreadsheet program that I wrote to calculate the plot in both Cartesian and radial coordinates of the shape described by the general equation of an ellipse for which the exponent can be varied from 2 to any higher value. The program calculates for any combination of length and width. Plot it full size on paper and transfer.

An example Super Ellipse in zebra

Clint Searl

Ooh, I like it

Bill Tindall, E.Tn.

That would catch your eye (favorably) when you walked into its room.

Re: Making an Oval Questions.....

Robin Corell in Atascadero

Ive do a lot of eliptical work over the years, some true and some less so. Early on I had an engineer explain that an ellipse is a cross section of a cone. So one method to draw an ellipse is to turn a cone and cut it at an angle and trace it. while this is pretty impratical I did try it out since I was given the diameter of the cone and the angel needed to make a pad on a pattern for an eliptical name plate for Jaccuzi.

often when making elliptical furniture you are given the width and depth or in math matical terms the major and minor axii. finding the length of string or the settings for a grinder then becomes trial and error. An easier method that produces surprisingly pleasing shapes if not true ellipses is to draw a rectangle that uses the desired major and minor axii as the length of the sides. next draw the major and minor axii inside the rectangle such that they intersect the sides of the rectangle and meet in the center.

now we will concentrate on one quadrant, or more succinctly the two lines that form one corner of one quadrant. divide the long line into 10 equal sized segments and then divide the short line into 10 equal sized segments. starting at the far end of the two lines that form the right angle start numbering the points up to #10, the corner becomes #1 for the next side. Now using a straight edge draw a line from 1 to 1 , 2 to 2, 3 to 3, etc. You can use 15, 20 , or more segments using this method for even better results.

As far as actually cutting out the wood I do things a bit different because of my background as a patternmaker. Using a bandsaw I cut to withing about 1/32" of the line and then sand to the line on a disc sander.

if you would like to see a table made using this method of generating an ellipse

here is a ling to a photo on my web page:

[URL=http://s453.photobucket.com/user/rcorell/media/furniture/just_a_cigar_zpswwuu1sib.jpg.html][/URL]

Re: Making an Oval Questions.....

Robin Corell in Atascadero

sorry but Im having problems inserting links and photos today, but of anyone really wants to see the table I was trying to link to it is on my web page at robincorell.com

Re: An example Super Ellipse in zebra

AZ in Colorado Springs

Very nice!

Your problem is Photobucket

Kneale Brownson

They won't let you link photos without paying them a bunch, I believe. I use Pbase, which lets you post lots for very little annual fee.