Elliptograph (?)

keakap · Post by **keakap** » Tue Jul 13, 2010 8:33 pm

A recent airing of Roy Underhill's Woodwright Shop showed- quite briefly- a device used to draw or mark on a workpiece an ellipse as a guide for a faux inlay, and Roy called it (I believe) an "elliptograph".

I had seen such a device before, but it had been presented as a "do-nothing toy", a rectangle about 6" square or 6x8, with through centered cross grooves and an arm that was connected to 2 blocks that rode in the grooves and extended well past the extent of the base with a pencil in that end. The whole thing drew an ellipse by virtue of running the pencil around the base, with the blocks sliding in the 2 grooves (in 2 directions at once).

I thought that would be a handy tool to have on hand, so I made one on the SS, after drawing a working model in CAD to make sure I'd seen it right.

But then I wanted to fine tune the thing and make it easily adjustable and, well, presentable, and not wanting to spend a lot of time on a redundant designing of the rotating circular support mechanism, so to speak, I went looking for a model that hopefully had done the grunt work (geometry) for me.

Alas, I searched the fori hi & lo to no avail, and everywhere else I could think of.

Thus my query:
Anyone built a device for drawing ellipses such as I described or similar? Just looking to save the tedious work of trial-n-error testing of varied size pieces for the adjustable feature.

Basic unit from scrap pieces is 5" square.

[ATTACH]9600[/ATTACH]

RonKlein · Post by **RonKlein** » Tue Jul 13, 2010 8:53 pm

You may be interested in one of the feature articles in the Lee Valley Newsletter I received today.
http://www.leevalley.com/en/Newsletters ... =160&lid=1
It is just what you are asking about.

Ron

keakap · Post by **keakap** » Tue Jul 13, 2010 8:54 pm

cant fix it, cant kill it,

??
igu

keakap · Post by **keakap** » Tue Jul 13, 2010 9:02 pm

RonKlein wrote:You may be interested in one of the feature articles in the Lee Valley Newsletter I received today.
http://www.leevalley.com/en/Newsletters ... =160&lid=1
It is just what you are asking about.

Ron

That's it, more or less!

Same idea, different approach, but the relationships I sought are there.
"... to fiddle with this process and make several,..." is an understatement, and exactly what I was looking to lighten up on.

This will be a great help. Thank you for the link.

(Dang- I thot I was on Lee Valley's email list. Musta dropped out.)

reible · Post by **reible** » Tue Jul 13, 2010 11:09 pm

As a FYI Rockler sells a jig that is called an ellipse/circle jig and has a large ellipse base add on. It is designed to use with a router (std Porter Cable hole layout).

I have both parts:

[ATTACH]9602[/ATTACH]

[ATTACH]9603[/ATTACH]

[ATTACH]9604[/ATTACH]

I made a small wooden adapter that fits in the jig that will hold a pencil so I can see what the circle or ellipse will look like (pencil line would be in the center of the cut).

In use the router is attached to the pivot arm, the base is attached to the work piece center. Next the arm is adjusted for length (radius) of the circle or the major/minor axes for an ellipse are set.

There are limitations and it is quite costly but it is made of a nice phenolic material. (I have seen the small base unit on sale for half price not long ago).

Ed

reible · Post by **reible** » Tue Jul 13, 2010 11:11 pm

The jigs can be found here:

http://www.rockler.com/product.cfm?page=17282&tagem=rv

http://www.rockler.com/product.cfm?page ... rcle%20jig

Ed

keakap · Post by **keakap** » Thu Jul 15, 2010 7:54 pm

reible wrote:The jigs can be found here:
http://www.rockler.com/product.cfm?page=17282&tagem=rv
http://www.rockler.com/product.cfm?page ... rcle%20jigEd

Thanks. Good visual references. I imagine since I wasn't interested in the idea the last time I perused my Rockler catalog I passed right on by it without a notice.
I hadn't thought about making a router jig for ovals, but now I may.

shipwright · Post by **shipwright** » Thu Jul 15, 2010 8:04 pm

I have always just used two nails and a string. (well slightly more technical but not much) The only drawback with this method is that if someone like Mickyd mic's it, it won't be accurate to his standards. that said no one has ever noticed on anything I have ever made and elliptical is one of my favorite shapes.

It's cheap, only takes a minute to set up and doesn't take up shop space. What can I say?

Paul M

mbcabinetmaker · Post by **mbcabinetmaker** » Thu Jul 15, 2010 9:32 pm

I use 2 boards and 2 nails. One nail set for the width and one for the height. A simple T shaped set up and it is accurate even to Mikeyd standards. I have made many entertainment centers with elliptical arches in the headers this way.

dusty · Post by **dusty** » Fri Jul 16, 2010 7:09 am

mbcabinetmaker wrote:I use 2 boards and 2 nails. One nail set for the width and one for the height. A simple T shaped set up and it is accurate even to Mikeyd standards. I have made many entertainment centers with elliptical arches in the headers this way.

I guess learning where to put the nails is the trick.