Solar parabolic cooker with the mechanical mathematician!

Step 8 Getting the string length right.

Remove the string from the hook and let the curtain rod drop till it touches the floor or foil. if you want a 10 inch high focal point, place your tape measure on the floor and mark the taut string at 10 inch height. Attach it to the 10 inch hook at that mark. For 12 inches, you have a mark at the 12 inch height and attach it to the 12 inch hook and so forth.