Woodwork Tools Blog

Nov

9

Woodworking Ideas – How to draw an ellipse (oval)

I was watching this short video (see below) on a woodwork tools jig used to draw an ellipse (or an oval), and whilst I was impressed by the simplicity of the jig, it also reminded me of another simple method for drawing an oval which I have used in the past.

The method I have used is even simpler than that shown in the video, and requires only a couple of nails, a loop of string and a pencil. Hammer the nails into a piece of scrap board, so that they are protruding by a 1/2 an inch or more and are a distance apart. Attach the board to the your work piece with some double sided tape (or any other method that won’t damage your workpiece).
Place the loop of string around both the nails, and use the pencil to pull the loop of string out so it remains taut, marking out the shape that is traced as you move the pencil around the two pivot points (the nails), whilst also keeping the string taut. You will find you have marked out a perfect ellipse.

The distance between the nails (like the distance between the dowels in the video) will define the shape of the ellipse – as the nails move closer together, the ellipse will tend towards a circle. Nails further apart will define a longer, narrower ellipse.

By using some basic math (which I have long since forgotten, but could no doubt work out if I sat down for long enough), it is possible to work out the distance that is required between the nails, and the length of string required, in order to mark out ellipses of specific heights/widths.

My technique uses the same concept (as I suppose any ellipse jig would do), of that shown in the video, and is probably quicker to set up (the only woodwork tools required to make the jig is a hammer), but the jig in the video certainly has a degree of elegance and magic about it that is just not acheived by using a couple of nails and a piece of string.

The only thing that does concern me with the jig in the video is the chance of a slight imperfection in the shape at the point that the two slots intersect – it would take a bit of practise to ensure that the dowel slides smoothly through the point of intersection rather than sliding down one of the perpendicular slots. Assuming you were just using the jig to mark out the shape (ie with a pencil), then this would be a minor correction, but if you were using a jig of this type to actually cut out the shape (eg by attaching a router to the end, instead of a pencil), then the results could be a little more disastrous.

Anyhow, check out the video, and if anyone has any other methods or jigs they have used for marking out an ellipse, please let me know! Enjoy your woodwork tools!

Leave a comment