Crafty Ellipse Jig

[mallymal]

OK, so here we have a little experiment making a wooden jig which you can use to draw ellipses... in my opinion a bit more sturdy and predictable than the pencil & string method. Of course this is only the baby version, for drawing an ellipse about 24" wide, but I'm sure the same idea could be scaled up. And of course with a bit of adaptation, it could even be adapted to fit to a router...

Step 1: Get a piece of 3/4 ply or similar and mark a big x on it, making sure the lines are at absolute right angles.

Step 2: Using a dovetail cutter in your router, cut along the x

Step 3: Make 2 dovetail shaped "sliders" - little blocks of wood (or even better nylon) which will freely slide, but not waggle, in your slotted base.

Step 4: Make a bar out of 1/4 ply or similar (I used plastic fascia), and drill according to size of ellipse... see pics for detail

Step 5: Screw through the bar where predrilled into the blocks... make them firm, but so the bar can pivot.

[Dan & Julie CO]

Cool

[kennyrayandersen]

yeah! sometimes you'll see a little toy made like that with a crank handle. Call me autistic, but I can turn and stare at it for hours!

All grown up it looks pretty useful!

[tonyj]

I built one very similar to that for my build. The arm was longer and I drilled a hole to hold a pencil to draw the quarter ellipse for the rear of the trailer. When I got the curve I wanted, I attached a plate and mounted a router to cut the panel. Worked great and I didn't have to cut with a jigsaw and then spend time sanding and fairing the curve.

[jesse c]

I work in a scene shop and before cnc i made a lot of various jigs,my favorite was my elipse jig.I didnt use a dovetail cutter but instead cut squares of plywood on table saw set to 45deg. and then glued those to another piece of ply using spacers made of uhmw plastic ripped to 45 on both sides looking like a dovetail and works as the sliders.My bar was made to accept a router and i had several sizes of boards and rails made up (with fancy adjustable connections i dont know how to communicate here)One set up using a pair of electrical conduit tubes could cut circles/elipses up to 20' diameter.I was so proud of the big set up i keep it in my collection even though cnc is the way to go now days