Pictures of the Parabola

Here is a picture of a parabola being cut out with a CNC. It's also a picture of a whole lot of dust. I took it a long time ago when I still had the first CNC I built. Machining time took about 4 hours at what I think was 30 IPM. It was actually my first 3D object. If I were to do it again, I think I could do it in less time because I have a better idea of what I'm doing now.  * That's possibly the biggest lie I've ever told.  : ) 

I'm not sure what type of glue really works on Mylar. What I used here is just Elmer's glue. The problem is that it will never really dry because the air can't get to it. It does hold the Mylar on however.

       It would have been better if I had cut the Mylar into small squares and glued them on, but I didn't want to spend a lot of time on it, so I just took one big piece and sliced it with a knife making several cuts starting from the middle and heading outwards.

There is just way too much light in this shot for my humble little digital camera to take a good picture, so you can't really see very much. The parabola is working however, and, just as formula predicted,  the focal point seems to be about 6.5 inches away from the bottom of the parabola.

      You can't see it in this picture, but the end of the stick is smoking. I couldn't quite get a flame out of it though. If I had spent a little more time gluing on the Mylar, it probably wouldn't have any trouble at all setting the stick on fire. One day I'll fix it, but, for now, it's good enough.