The Light Sharpener

Intro Build Foil Mirror Burn Epilogue FAQ
1 2 3 4 5 6 7 8 9 10 11 12 13 14

15 16 17 18 19 20 21 22

23 FAQ

As with most big projects, I was hesitant to tear off the perfectly amusing foil and move on to the next part of the project. However, this dish promised much more.



I tore off the foil and locked the dish into position, up into the sky. The first three weekends in the month of June were booked, so I planned to leave the dish uncovered for a few weeks.

This would allow the grass under it to get a little sun.

Moving the dish.

This is also how the guys on the Death Star do it.

I actually considered selling this lump of aluminum foil on ebay. However, Experience tells me it would only fetch a few dollars.

I had cut 600 mirrors, and figured I would need about 400 more to cover the whole dish.

I was worried about gluing on the mirrors. Everyone I had spoken to, and all of my previous experience had told me that I had to aim the mirrors individually. But I just didn't want to. A thousand mirrors? I was sure it would take forever.

I could imagine suspending a laser-pointer on a huge grid, acting as a single ray of sunlight, striking perpendicular to the dish. If a particular mirror reflected that laser beam to the focal point, then the mirror would be aimed. Another method would be to aim the mirrors in sunlight, covering all the other mirrors with post-it notes, so that its one bright square of reflection could be moved to hit the focal point.

After a long internal struggle, I decided I could get away with not aiming the mirrors. I would rely on the curve of the dish to keep the mirrors pointed in the right direction.

The next problem was adhesive. Eric, my tile-setting friend, had recommended using lightweight mastic, applied with a hand trowel. This seemed like a very professional solution, but I was worried about the days-long drying time. I was also concerned about the weight, and about whether the mastic might be a little too permanent.

Another friend, also named Eric, recommended using "Liquid Nails", an elastomeric adhesive, to attach the mirrors. I decided to try it.

I chose four mirrors to start with. Each of them were missing one corner, which left room for the center pole between them.

Outside of that initial set of mirrors, there was a circle of bolt heads in my way. Cosmetically, it would have been better to glue mirrors on top of them, but if the mirrors were resting on the bolt heads, they would have been all cockeyed, and if they weren't sitting flat, there was no point in having them on there at all.

I left gaps.


I had plenty of glue and plenty of mirror squares.

The "Liquid Nails" worked well, depending on the angle of the dish.

If I was trying to stick mirrors onto a nearly vertical surface, I would usually have to support it with a few pieces of masking tape until the glue dried.

It was looking good. Rows and columns of 4" square mirrors. The decisions were now behind me. I just had to do the work.

Please continue reading page 12 of the light sharpener

Intro Build Foil Mirror Burn Epilogue FAQ
1 2 3 4 5 6 7 8 9 10 11 12 13 14

15 16 17 18 19 20 21 22

23 FAQ

Other incredible stuff  | Home | Contact Rob | Making fire with two sticks | My first solar parabola | Fire with Coke can and toothpaste

July 9th, 2007.   Terms and Conditions  Copyright 2007