Part three of the construction - making the mirror
| Page Link: |
| I test fit the Mylar
plastic first and rough cut it to match the basic dimensions of the
dish. I left plenty of space material all around the perimeter.
The material is creased from being folded, but if you buy Mylar by the roll, it will be flat and uncreased. The application and tensioning, however, will remove the creases anyway. |
 |
|
| A bead of silicone rubber
was laid around the rim of the dish. This was tacky enough to keep
the Mylar in place as it was tightened. I used clear tape to hold
the opposite edges at top and bottm, and then applied it to the right and
left edges also.
By adjusting the tape in segments completely around the Mylar, I slowly brought the entire piece of plastic into tension. I left the clear tape on the dish and let the silicone set overnight. This left the Mylar flat and taut. The reflection shows just how flat it ended up being. |
 |
With the dish ready for mounting and the frame and pivot completed, it only remains to add the focus control system. That is done with an air fitting from an aquarium supply house, a small vacuum pump, and a battery to power it.